building my own acrylic aquarium  9/23/09
To whom it may concern,
I have been reading over your FAQ's on DIY acrylic aquariums all night.
I just have a few questions if you don't mind?
I plan on building an acrylic aquarium that measures 96Lx48Wx24H.
According to the garf.org website it recommends that I use 1/2" cell cast acrylic.
<Or thicker... the 1/2" is going to bow a bit in the middle of the long panels>
After reading over your FAQ's I came across a response were it stated that if the aquarium is wider that 32" the thickness of the acrylic must be at least 3/4" thick.
<Yes>
Upgrading to this thickness is out of my price range. Would 1/2" acrylic suffice?
<If the bottom is sufficiently supported (as in 4 by 4's) yes... just the bowing in the mid front and back panels...>
When building the acrylic aquarium do place the walls of the aquarium on top of the bottom acrylic sheet or do you place the walls on the side of the bottom sheet?
<On top>
I do apologize if you have answered this question already. I must have overlooked it when I scrolling through FAQ's.
Thanks for all that you do!
Brent
<Glad to help. I would get some help here from folks who have acrylic experience. Not hard work to do, but easy to make simple errors. Bob Fenner>

Acrylic pipe for an aquarium, RMF's go   7/14/2009 Hi, I am interested to build an aquarium using acrylic pipes. This aquarium will be filled with water (the aeration of the water will take place in another tank) The diameter is 30 in. and the length is 50 ft, divided in 10 sections of 5 ft length. <Interesting> The simple thing would be to buy the pipes, but I could not find them. The dimensions could be modified, if there are some commercial options available. + Do you know if there are commercial suppliers of acrylic pipes for this diameter? <Mmm, I do not... But I do think this could be fabricated...> The option I am currently exploring is to bend 20 pieces of cell cast acrylic sheet (see attached file) and I have the following questions: + to calculate the acrylic sheet thickness, I should only consider the water column height, which is 30", so the adequate thickness is 3/4"? <I think you could get away with 1/2"> + in order to assure no leaks, would it be better to glue the joints, or to follow a solvent welded process? <Solvent or sonic> + which type of support would you recommend for this design? <Something sturdy... bead-blasted steel rod, with a "V" shaped support at the bottom> + in addition to visual inspection, is there any other method to check for cracks, bond failures, or crazing, as a preventive maintenance program? <There are non-invasive techniques...> Thank you. Francisco Velázquez <I'd contact Reynolds re: http://www.reynoldspolymer.com/ Bob Fenner> Tubular Aquarium. MikeV's go  7/15/2009 Hi, <Hi Francisco.> I am interested to build an aquarium using acrylic pipes. <A different approach.> This aquarium will be filled with water (the aeration of the water will take place in another tank) The diameter is 30 in. and the length is 50 ft, divided in 10 sections of 5 ft length. The simple thing would be to buy the pipes, but I could not find them. <There are several facilities that can get it for you. here is one: http://www.spartech.com/townsend/acrylic_tubes.html> The dimensions could be modified, if there are some commercial options available. + Do you know if there are commercial suppliers of acrylic pipes for this diameter? <Yes, see above.> The option I am currently exploring is to bend 20 pieces of cell cast acrylic sheet (see attached file) and I have the following questions: + to calculate the acrylic sheet thickness, I should only consider the water column height, which is 30", so the adequate thickness is 3/4"? <You can go a little thinner as it is tube and pressure is applied evenly to all surfaces. you should be able to use 5/8" (16mm) + in order to assure no leaks, would it be better to glue the joints, or to follow a solvent welded process? <Solvent welded.> + which type of support would you recommend for this design? <That is largely dependent upon where the tank is going to be displayed At a minimum, supported at each joint and midway through each span.> + in addition to visual inspection, is there any other method to check for cracks, bond failures, or crazing, as a preventive maintenance program? <None that are user friendly that I am aware of.> Thank you. Francisco <My pleasure, MikeV>

Re: Acrylic pipe for an aquarium 7/15/2009 Thank you Bob. <Welcome Francisco. Please do send along some images of your project... In fact, do consider writing up your experiences in an article for sale to the pulp and e-zine outlets in our interest. Cheers, Bob Fenner> Re: Acrylic pipe for an aquarium 7/15/09 Thank you Bob, it may take some time for this development, as there are many uncertainties, but certainly it would be a very good article. I will let you know. <Thank you> One more question. If I need an acrylic tank, lets say around 30 inches in diameter, and 44" height, constructed with a cast acrylic sheet, thermoforming: is a thickness of 9 mm adequate? <Mmm; I'd rely on the fabricator to tell you... but would go with 12 mm minimum myself> The seam will be welded along the length. The tank will be filled with water. Would it work to put a steel belt around the reservoir to add mechanical strength and avoid a thicker acrylic? <No; not a good idea> I know the optics of the acrylic is affected, but this tank is for a laboratory. Best regards, Francisco <Do contact Jim Stime, a friend who does such custom installs, large round acrylic... re... I'm cc'ing him here. BobF> Re: Acrylic pipe for an aquarium 7/15/09 Hi Bob and Francisco, Cylinder tanks are very very expensive. I have known of three cylinder tanks in the LA area. Two of them were seamed and they both split their seams. One was local and flooded a surf clothing shop, the second I only heard about. The third is a 'spun-cast' seamless cylinder that I installed myself locally ( 44" diameter X 66" tall ). You can see it in many of the LA Fishguys aquarium reality video shows on-line. If cost is an issue or you have an area that would not be affected from a seam failure of the tank then go for the seamed version. If you have the money and are looking for a safer tank I recommend the 'spun-cast' version. Note that this version has specific predetermined diameters and depending on who your vendor is you may be forced to buy a certain length / height as well. Jim Stime, Jr 805-241-7140 Aquarium Design - www.aquarium-design.com MyFishTank.com - www.MyFishTank.com Midwater Systems - www.Jelliquarium.com LA Fishguys - www.LAFishGuys.com <Thanks much Jim. See you soon... IMAC west I guess; end of the mo. BobF>

A Good Laugh 09/20/09 I was looking at my website today and found this thread. One of my sites members Chris, ( a really nice great guy btw ) was DIY ing a sump for his reef tank. After completing the sump (and eating dinner) he realized that the 2 containers he had used to hold the baffle in place were sealed inside. The look on his face is priceless. lol A Jenkins <Wot a hoot! Am sure SeaChem will be happy to see another ap. for their line... Heeee! BobF>

Thank you in advance... Your site is great! Acrylic sourcing    4/11/09
Hello,
<Ryan>
Do you happen to know of a one stop shop supplier (with a variety of colors, etc.) of acrylic plastics close to Minneapolis, MN?
<Mmm, I do not, but I do have some ideas...>
Sorry for such a boring question! I keep finding wholesalers, and none seem to be specialized in plastics. I only need a little bit once in a while because I'm a student. Perhaps 24"x24"x1/16" to 1/4". Any suggested
online sites with good prices and staff will also be considered. Thank you...
I will be making small scale architectural models and will be cutting with a laser.
<Neat!>
Any advice on which Weld On formula (or other) would be the best?
<Likely #16 here>
I would like it to set very quickly for small pieces, without clamping if at all possible. I will also want to use a syringe like applicator so it doesn't get too messy. Thanks again!!!
Ryan
<Take a look in the on-line and in-print "Yellow Page" directories... In a town of such size there are likely a few outlets. In this thickness, even the larger "hardware stores" (Home Depot, Lowe's) will likely carry sheet for resale. Bob Fenner>

Thank you in advance... Your site is great! ScottV chimes in   4/11/09
Hello,
<Ryan>
Do you happen to know of a one stop shop supplier (with a variety of colors, etc.) of acrylic plastics close to Minneapolis, MN?
<Mmm, I do not, but I do have some ideas...>
<<I have a few, but for the quantity you are talking about you may be better off going to a local store and buying "scrap" material. Even Home Depot or Lowes carries an extruded acrylic that machines better than some of the cast acrylics out there.>>
Sorry for such a boring question! I keep finding wholesalers, and none seem to be specialized in plastics. I only need a little bit once in a while because I'm a student. Perhaps 24"x24"x1/16" to 1/4". Any suggested
online sites with good prices and staff will also be considered. Thank you...
I will be making small scale architectural models and will be cutting with a laser.
<Neat!>
Any advice on which Weld On formula (or other) would be the best?
<Likely #16 here>
<<If this is indeed laser cut, to a good point of precision, do use #3 for a fast setup. Scott V.>>
>>Oh! Want to state my reason/rationale for the #16... I have found that folks who are very new to acrylic work need more time, jelly-like solvent, even if the pieces are "jointed" or precision-cut... RMF<<
I would like it to set very quickly for small pieces, without clamping if at all possible. I will also want to use a syringe like applicator so it doesn't get too messy. Thanks again!!!
Ryan
<Take a look in the on-line and in-print "Yellow Page" directories... In a town of such size there are likely a few outlets. In this thickness, even the larger "hardware stores" (Home Depot, Lowe's) will likely carry sheet for resale. Bob Fenner>

Cylindrical tank. Acrylic des.   11/14/08
Dear Crew, Hi!
I am a big fan of your website and truly appreciate the help and information you are giving everyone.
I am building an Acrylic aquarium which is cylindrical in shape. It is of 8mm thickness(5/16th of an inch) thickness which is a little over a quarter
of an inch. The diameter is 28 inches.
What is the maximum height I can make it without having the aquarium break.
The acrylic is going to be die cast type not extruded. Also what would be the capacity of the tank in the suggested height in Gallons.
Thanks for your advice in advance.
Kind Regards,
Raghav Kochhar.
<Mmm, I wouldn't go over 20" in height with this thickness and type of material... the volume... Pi R squared times the H (divided by 231 cubic inches per gallon)...
http://wiki.answers.com/Q/What_is_the_answer_for_finding_the_volume_of_a_cylinder_8_height_and_3_base
here would be about 53 gallons, before taking out volume for gravel et al.
Bob Fenner>

Acrylic Build Question – 02/07/08 I am currently looking into building a wood tank with a large viewing panel on the front and a small one on one side. My question is about the large one. Would 1" thick acrylic be good for an 86" x 48" panel? >... no< The water level would be over the top of the panel. I have posted a picture of the tank design (sorta bad picture). What do you think, is 1" good enough? <Will deform too badly, fail...> The water height would be about 60-65" total the extra 10-15" would be the bottom bracing and some space at the top for lighting and fans. <... how do you intend to seat/seal this viewing panel?> The panel would be a little of the bottom of the tank so there maybe say 5" of water then the panel for 48" then water for another 8-10" or so above the top above the panel. A little background on why this size tank, the only way for me to upgrade tanks at this time is to make it fit in the spot my current tank is in, so taller it has to be. Here is a picture of what I am thinking http://www.marinelifeweb.com/woodtank/images/front2.jpg Thanks, Eric <... I would use a minimum of 1 1/2" thick material here... And read over the DIY tank making materials archived on WWM... Am concerned re responding just directly to your query here... as it may well be leading you astray by not addressing other, vital issues. Bob Fenner>

Acrylic Tank Construction Advice...Going Rimless?...Best To Consult A Tank Builder/Manufacturer – 10/03/07
Gentleman,
<<Greetings Dennis...and BTW...very capable Ladies here as well>>
I am constructing a large acrylic aquarium (50x50x30).
<<This is “inches” I presume?>>
I intend to use 3/4" acrylic for the bottom and sides and initially wanted to keep the top open; but realized this probably wouldn’t work.
<<Mmm, no...not at this height, with this thickness of acrylic>>
At best, this would leave a tank with heavy bowing on all sides.
<<Very heavy, yes...>>
At what acrylic thickness would you use to keep an open top and also prevent any bowing?
<<Hmm...can only speculate, but likely thicker than is practical (1.5” or more)>>
If this is not practical, then what width would you use for a Euro-brace that was 1" thick over the top of the aquarium?
<<”One-inch” is probably not heavy/thick enough for the Euro-brace to keep the dimension small. I have a 30” tall acrylic tank made from ¾” material (sides and top) that has a 7” apron around the top perimeter WITH two 10” cross-braces (8’ tank). The tank does not bow, but is quite the “pain” to work in so I well understand your wish to go “rimless”>>
Regards,
Dennis
<<I very much suggest you poll a broader audience and/or speak to someone who manufactures such tanks as a matter of routine. You could either contact a manufacturer like Tenecor, or give the DIY forum on Reef Central a try. Tenecor was very helpful with suggestions/advice when I wanted to make some modifications to my tank...but then I bought it from them. The RC forum has a couple guys who manufacture acrylic tanks who routinely peruse the forum and are willing to answer questions/provide advice (one called “Acrylics” (James) comes to mind...you might even try sending him an email or private message). Good luck with your project. EricR>>

Acrylic fabrication  2/12/07 Hello....I am building some acrylic fish tanks (1/2 in cell cast 36*24*24 full top panel with cut outs) and was wondering what method  you use to heat the acrylic for bending. I would love to be able to use 1/2 inch and bend it. <Mmm... well... you could build/fashion a heat table as we and others have... with an element (electrical) flanked by two cold water pipes (flat)... and a second-time piece and standards for tilting the acrylic panels up to the appropriate angle in time... But I would likely call, use these at a local fabricators rather than build my own for a one time use> Also do you use shims when bonding with the Weldon 3? <Not usually... but a good idea to use gigs or wood clamps at least to hold all in relative place...> I have heard that using small wire shims will raise the panel a SMALL amount. <Yes... too much with thin material (under an inch thick let's say)> This supposedly allows better flow of the solvent. <Mmm... not necessary... the solvent will easily flow/occupy the gap if cut right, fitted closely> You remove them just after applying the solvent and then lightly clamp the panels. <... Uhh... I'd be practicing with some "cut-offs" if I were you... before trying the "real thing" here> I usually have good results not using them but there are a few places on the joint that do not appear to have full contact. <Not good... bad cutting...> The joints do not fail but they are not crystal clear all the way like the store bought tanks.  Looking for any tips you may have <I'd be inserting some corner bracing...> Also how do you start building a tank? <?> I started by lightly clamping the front. back and sides together. I then placed that onto the top panel (upside down) that I had already cut out for access. <Good... this is how I, and our "old" companies used to do... for small/ish systems> I then solvent welded the top and the sides. After that set up I flipped it over and set it onto the bottom panel. I reached through he top panel cut outs and solvent welded the bottom panel. Here area couple pictures of the 90 gal I just made. <Very nice!> I added the back panel to the black top after these pictures were taken sorry for all the questions but I value your advise on this. LOVE this site!!. I am getting ready to build a new 8*24*24 240 gal tank to go in the wall <Sounds like you're ready! Cheers, Bob Fenner>

Re:... acrylic tank white-out seam repair?   2/14/07 Ok so I should get some 1/2 inch wide and 1/2 inch  thick square stock to use as reinforcement along the inside joints? <Yes, I would for sure... Do take a close-look at the square stock... often it is only really square on two sides... the others being convex... Of course you want the truly square faces against the repair> Also I was wondering if it would be safe to router the  edges of the  tank so that they are a bit round and not such a sharp corner. <Yes... as long as the joints themselves are left intact> I was thinking a  1/8 inch  or so. I was prepping the next sheets I am using for the tank I am building now. I used 400 wet sanding to remove any machining marks and make a totally smooth surface to solvent weld. Hoping for some crystal clear welds  :) <Yes... Want to mention (for you and posterity) that you might want to look into a "higher number" Weld-On product (more gel-like)... and perhaps better gear for cutting the sheets... should be flush, not require any sanding...> Thanks again for the help!! Ed <Welcome. Bob Fenner>

Re: Acrylic fabrication  - 02/15/07 OK I will router the edges some to knock off the corners and I will make sure that the square stock I use as reinforcement is perfectly smooth on  the contact sides.  I was also wondering about a triangular rod that would  fit into the corners.. any ideas on that? <Have used this as well... Will work, yes> The place that I get the acrylic from cuts the panels to my specs but I am sure they are not using a $200 blade either to make the edges finished. <Mmmmm... am surprised the edges aren't more "clean"... Do they have suggestions re sanding them smooth?> The Wet sanding worked awesome. I now have welds that are 99% crystal clear. <Mmm... okay> I took a  2x8 inch x .50 inch scrap and solvent welded another identical piece on top as  in a  "L" shape. I then cut 1.5 inch strips of sand paper and  used it as a guide block for sanding. This worked great for keeping me  square on the edge <Sounds good> I used the #3  because I was under the assumption that it was  the solvent of choice I have read that  the #16 gel was not as strong  and therefore not to be used for actual joints but ok for baffles and such.. I  heard the # 4 was just a tad bit slower in set up/dry time I used a similar  solvent to the #3 about 15 yrs ago when I made my first 240 gal tank. <As an important note here... I met with friend Leng Sy/EcoSystem yesterday... he was down picking up a good quantity of #3... Said that Weld-On has changed formulations in recent years... the number 3 is what most everyone uses on the west coast...> It  held up great but unfortunately was dropped during a move and suffered some  cracks. The place that cut those sheets for me used a blade that did leave a  really level edge on it. <Good> Again, thanks so much for your input and advice. I appreciate the time and effort it takes to do this. Ed <Thank you for the input and clarifications. Much appreciated. BobF> **On a personal note I have owned a Mortgage Company for 18 years so if you have any Mortgage related questions please feel free to ask   :) <And for this!>

Re: Acrylic fab... and fab tools!  2/18/07 OK I went out and bought a nice Delta planer this weekend. <How nice!> I can now clamp the panels together, run them on the  planer and make them all the  exact same size and finish the edges in one move :) This thing is just awesome,  what a time saver. It weighs @200 lbs so it was a bit of a load to get down  in my basement by myself, but I won the battle :) <Oomph!> I built the base of a skimmer I am making for a guy and the joints are just beautiful! <Great> What is your opinion on Chemcast Acrylic? I have read in one place from a very experienced tank builder not to use it for aquarium use. I searched trying to find more info but could not. <Mmm... I have heard similar opinions from folks re this Mexican co. product... though they are (admittedly) one of the largest producers in N. America... I have heard, what I would couch as rumours, that it (as a general stmt.) is "too soft"... that sometimes their sheets are inconsistent in thickness... quality> I hope he is wrong but if not then the 2 tanks  I just built will be reptile tanks I guess. Thanks again Ed <Good attitude. Thank you for sharing. Bob Fenner>

Drilling Acrylic
Can anyone offer some experience/advice for the placement of holes in acrylic tanks in relation to the seams? I'm setting up a large reef system and I'm plumbing 1 inch bulkhead returns (two per end) in the ends of the 3/4 inch acrylic tank. I want to place the bulkheads as high as I can and was wondering if I can drill the holes right next to the top seam? My understanding is once acrylic is solvent glued it's essentially all one piece, yes?
Thanks!
Eric
<My general "rule of thumb" is to leave gaps at least as wide as the cut out diameter from seams. You can adjust the water height in the system with plumbing distal to the tank if this is a/the concern... either ell's, tee's or valves. Bob Fenner>

Acrylic pricing
In my never ending search for better pricing on acrylic sheet, I have noticed a great difference in pricing by web searching. Is the only difference the competition between companies in their area? Or are there other circumstances that I should be aware of.
<There is some local variation, but the trade in acrylic is highly layered in terms of master distribution, volume discounting>
I have found one company out of Utah that sells a 4x8x1/2 sheet of cell cast for about $195 + shipping (truck line) and free cutting down to 24 x 48 for UPS shipping. So far this is the best deal I have come across.
<This is indeed a deal... do check re the quality of the sheet however... buy brand name/s if you can... as there is some important variation in this product... some is quite flexible... some more soft, easier to scratch>
From a business point of view, are there any lower prices out there to either maximize the bottom line or sell the end product at a lower price than the competitor? What info if any can you give me? Thanks again for your glorified answers oh wonderful master.
<Good questions... as I don't have ready answers (!)... if you can deal in volume (not likely), there is quite a bit of "wiggle room" in negotiating. Bob Fenner>

Re: acrylic pricing
I emailed this company in Utah and they wrote back they carry Lucite L, Chemcast and an import sheet.
What is the best of the 3? and are they good for aquariums?
<Very likely the Lucite L... there are specifications for all acrylic... you should request these spec.s and endeavor to understand what they represent. Bob Fenner>

Acrylic pricing update
would I contact the manufacture directly for the specs?
<Joe, not to step in here but just wanted to let you know some things. I'm sure Bob will also jump on this question.  Acrylic pricing is currently going through the roof because as you know it is an oil based product. I know that the cost of the custom tanks we've been making has pretty gone up simply because prices of acrylic have gone up so high. Most local plastic places will meet online prices or come pretty darn close and its pretty standard for most acrylic places to do at least three "cuts" per sheet. Also, generally if you buy more than one sheet you can get them for a much better price than if you just buy one sheet. They generally have prices for one sheet, two to nine sheets and then nine and above sheets.  
Most of the specs on acrylic brands can be found online because most of these companies have gone on the web. But let me also make you aware of something that's out here recently and I'm not telling you that this company is guilty of it, just making you aware of what to ask. Make sure you know the age of the acrylic.  While acrylic doesn't really age there can be problems with what's been on the acrylic while it is sitting around so be sure and ask the AGE of the acrylic that these gentleman are selling.  Also, there are rumored to be problems with the imported acrylic and gluing. I personally haven't used it so can't tell you whether that is the case or not. One thing I look at closely when I look at acrylic specs is the ability of light to pass clearly through it. Just my two cents.  MacL>

Re: acrylic pricing
would I contact the manufacture directly for the specs?
<You could, yes. They should be available on the Net though, and distributors have these as well. Bob Fenner>

Re: acrylic pricing
I went to the manufactures websites for Lucite and Chemcast and Lucite seems to be the better of the two products. Chemcast as far as I can tell is an import from Mexico.
<Yes. Bob Fenner>

- Building My First Acrylic Tank -
Hi There,
First off, I've been addicted to your site and check the new FAQ's daily for useful info.  Anyway,  I want to start building my own acrylic tanks and I have found a detailed instruction book on the web which shows exactly how to design right through to how to use the solvent's properly.  The only thing is I not completely sure on thickness.  Since this is my first tank I am starting small and would like to build about a 30-40 gal tank for my 2 dwarf gouramis, yo-yo loach and red fin shark.  My problem is that the instructions say that 1/4 inch is good enough for tanks up to I think 12 inches (I have misplaced this valuable info right now) and 3/8 inch is good up to 18 inches high.  I have read on your site that length of a tank doesn't matter only height but can I really build a tank that is 12 inches tall and 48 inches long out of 1/4 inch? <I wouldn't... it's always worth while to overbuild, have a margin of error. Likewise, the thickness will really be determined by the materials. You can get specifications from the acrylic manufacturers that will serve as a guide.> This wouldn't be the an ideal tank but for argument sake is this actually realistic.  I am obviously asking because 1/4 inch is so much cheaper but it will cost a lot more to clean up all the water when it lets go. <True.> I am still planning to use 1/4 inch for my first tank just so I don't waste a ton of money on a failed tank.  I will build a tank smaller with a divider (basically two separate tanks in one)  for my feeder fish (I know they're not the best but my red bellies refuse dead food) so that one side is QT for a month and then get moved to the "safe to eat side ". This would be about a 20-25 gal tank.  Your expertise would be greatly appreciated. <Well... as an experimental build, I'd encourage you to hone your skills with the cheaper materials. Tanks can be placed outside on a flat surface and filled with a hose to see how they hold up. Once you have your design and technique down, then go for the more expensive materials.> The real reason I want to start building my own is my piranhas are going to be needing a bigger tank soon (next 3-4 months) and I would like to build a tank for them which is going to be around 60-75gal as I only have two.
Thank you in advance
Mike
P.S if you know of any ways to get my piranhas to eat anything but feeders that would be great.  I've tried mixing live with salmon chunks, krill they eat sometimes, but usually they refuse and then the fin nipping and body wounds begin.  Starving is out of the question as one has just recovered from an eye injury caused buy the other during my attempt to starve them so they would eat something else.  They are about 4 and 4.5-5 inches long right now and GROWING!  Thanks! <Is perhaps the major drawback of piranhas... think your plan to quarantine feeders may be your best bet, that and continue trying to mix in other foods from time to time.
Cheers, J -- >

Bonding Silicone/Lexan Plexiglas
Could you tell me if silicone will attach Lexan Plexiglas to a glass aquarium or if you can only attach glass to glass with silicone?
Thanks,
Amy
<Silicone will weakly bond Acrylics, but are not to be trusted in aquarium applications of any real size/depth. Solvents for this purpose are the route to go. Bob Fenner>

Acrylic question
Hey, WWM-ites (particularly the acrylic construction experts), <Hi Glen, I don't know what you consider an expert. I just delivered a six foot acrylic tank so my family builds them. Hopefully that qualifies me.>
Things are plugging right along with the 55 gal community tank.  We're stocking up, and nearing our piscine limit.  Chemistry is performing nicely, pH running 7.0-7.1 and our weekly 20%+ water changes are keeping the nitrate levels at just over 10 ppm.  We've moved the eight surviving baby Swordtails to a 5-1/2 gal tank, along with a Panda Cory and a
really cool Mayan statue head (just to irritate my wife!)<I LOVE IT!>  In the big
tank, we've replaced the fake driftwood arch with a real cypress driftwood arrangement (for the Otocinclus to gnaw on), and have replaced most of the fake plants with real ones, including a line of Vallisneria, quite a Cabomba forest, dwarf and giant hair grass, planted (huge) and floating watersprite, java moss, and red Ludwigia and Alternanthera.
We're waiting for the plant-carrying LFS to get a red water lily to finish our live plant assortment. <Get a dwarf lily or you might have size problems lol.> We've upgraded to a four-foot 110-watt AGA compact fluorescent fixture, which really makes the colors snap.
The plants are doing well with the higher light level (duh!), and I'm
hoping their consumption will start reining in the rather amazing algae
growth. <It will, I know its got to be frustrating though.> I have roundly chastised myself for overfeeding the fish (new owner, poor-starving-fishy syndrome) and causing the algae bloom, but I'm going to let nature take its course (thanks, once again, to the
advice on WetWebMedia!)  I haven't decided whether I'm going to do any CO2 augmentation for the plants.  Maybe in the wet-dry, which brings me to the topic of this query. <Bring it on!>  
I've designed a DIY wet-dry filter, big enough to support multiple tanks when we get into our non-rental in a year or so. <Ooooo nice.> The sump portion will be 24x13x13, and the removable biotower will be 16x16x12 (biomedia capacity just over 7-1/2 gallons).  2" deep floss/media/drip tray drawer, Mag 7 pump, Durso standpipe fed by a Busko surface extractor,
etc. etc. etc.  Investigating the types and recommendations for the acrylic has me going in circles. <Ahhh that one I can help you with, we've made many, many sumps and wet/dries.>
Questions (and please don't be gentle - if the answer is "quit obsessing, buy the cheap/expensive stuff and build it", feel free to say so!): <I would never say it in that way, to my way of thinking you simply cannot do enough research when you are doing something for your tank!>
I'm leaning toward 3/8" acrylic, but 1/4" is sure cheap! <You really do not need the 3/8, with what you have designed you won't get any bowing. Your height really determines the stepping up in size of the acrylic. If you keep each piece cut under 24 inches tall you should be just fine.> I've designed in 3/8" square cross braces in the biotower and sump, to control bowing in the longer spans of plastic. <The bowing won't be significant enough that you'll need the 3/8ths, simply brace with 1/4 and you'll be just fine.>  Total catastrophic power-outage water load will be a bit under twelve gallons.  I know the 3/8" will provide
structural integrity and the "gee whiz, look at the pretty acrylic" factor, but would 1/4" really work just as well?  Of course, this ignores the 5/16" and 9mm stuff! <I promise you that it will work as well.  Now just a few hints.  Route the edges because plexi is sharp and it will cut you, if you route the edges or you flame polish them regardless of the size it will eliminate most problems in cutting.>
Most of the tank-building sites say (essentially) not to think about anything less than cell-cast acrylic.  I've seen all the reasons why - superior clarity, harder surface, nicer machining characteristics, etc. In small quantities, cell-cast is danged expensive - I haven't found it for anything under $7/sq. ft. for 3/8" material.  Continuous-cast, on the other hand, can be had for just over $4/ sq. ft. for 3/8", and extruded less than that.  Other than the "gee-whiz" factor, is there a compelling reason to go with cell-cast for this project? <Cast acrylic, continuous cast acrylic and extruded acrylic are types of manufacturing processes. Each process is made from acrylic with different properties and subsequently show different characteristics in the fabrication process and in the finished products. Cast acrylic is the most dense and therefore the strongest. It also tends to bond with the strongest seams. For aquarium applications use domestic brands (Polycast, Acrylite GP, Plexiglas G material) I use the Plexiglas G most frequently. Continuous cast material have a density close to Cast materials. (Lucite material) Good for small aquariums, filters and museum quality display cases. Extruded is an inexpensive low-density material for Point of purchase displays, signs etc. I just don't think with extruded that you will get the attachment you need with the water pressure.>
What will be the disadvantages if I use continuous cast?  I'm leaning away from extruded - is there a particular brand that would justify my rethinking this?  If cell-cast is really that much better/easier to work with/more stable over the long term/other, I can convince myself to spend the extra money (over continuous-cast), but why spend unnecessarily?  Should
I spend any time looking at Lexan or other polycarbonates, or is that super-duper-extreme overkill? <Lexan is beautiful but sooooo expensive. Frankly I can't touch it here.>
If you have any other suggestions, comments, guidance, or whatever, I'd appreciate hearing them. <I think you'll be happy with the thinner Plexiglas for this particular project.>
Once again, thanks for your fantastic site!  I noticed your "support this site" link at the bottom of the homepage.  Is it new, or have I been that inattentive?  I'll be chipping in as soon as I clear it with the Bride. <We are trying hard to keep the site free and of course the answers. But it takes a large amount of money to maintain this site. I'm glad you find the site helpful and please let me know what you do and how it works. MacL>
Glen

Another acrylic thickness question
Hello to all. I stumbled upon your site about 6 months ago and now read it daily ... a wealth of information and a joy to read. I am in the planning stages of my dream tank: a 300 gallon (96" x 24" x 30") FOWLR (I love angels and butterflies!) Most of the inhabitants and some equipment will be coming from an exiting 125. I have everything planned, including equipment requirements, plumbing diagrams, even my livestock wish list. When I went to order the tank, I realized I had one unanswered question. The tank is being built by a company called Tru-View and will be made from 1/2" acrylic for the sides and top and bottom. My existing 125 (72" x 18" x 20") uses 3/8" on all sides except the back which is 1/2". The thickness of the new tank has me concerned.  I spent several hours reading you posts regarding thickness recommendations and am still confused. I don't mind a little bowing, but I do live in earthquake country (Northern California) and want a tank that will be as safe as possible. The tank will reside on concrete slab in a finished garage / playroom. So, is 1/2" good enough? Or would you recommend 5/8" or 3/4"? Thank you for your time. Dana 
>>>Hi Dana,
I'm very familiar with TruVu, and have owned many tanks made by them over the years. They are actually made locally not far from my house. I've also had a number of tanks custom made over the years. What you need to be concerned with is "thrust" which is the pressure the water exerts against the inside walls of the tank. This is a function of the height of the tank, and the width. As long as you stay below 26", and no wider than say 32", 1/2" works, even if the tank is 10 feet long. Although 1/2" is standard on certain tanks, and will work just fine on a 24" high tank, any higher and I'd go up to 5/8". Since it's only 24" wide, no reason to move up to 3/4". It will NOT provide more earthquake resistance (I live in California too) but it will not bow nearly as much, and it will be stronger. The thicker the acrylic, the more surface area on the joint. Just a piece of mind thing. In general, even on smaller tanks, I always kick the thickness up a notch.
Cheers
Jim<<<

Plastics Suppliers 2/15/05
Hey all,
<howdy>
Do any of the Pittsburgh folks know where I can go to buy acrylic scraps and/or sheet material? I am looking for pieces to build a sump. Thanks! Ed
<locally is a bit expensive at places like Cadillac Plastic if still in business. You may want to simply do mail order. US Plastics Corp (Lima, OH... Google them) has a big inventory, not the cheapest prices though, but great customer service and fast shipping from OH. Anthony>

- Refugium Construction -
Hi, I would like to thank all of the crew members at WWM for all of their quick and helpful responses they given me. I tried to search for a question similar to mine, but I couldn't find what I was looking for. 
<Seems odd... I answered a similar question not three days ago.> 
I am working on a 15 gal. sump, actually it is running, but I do not have it chambered so I can make it a refugium. I think to convert this I would just need to seal two panels, one on each side, so that the center would have most of the flow going over the top and not affecting the middle chamber. My first question is, what would the best material to use as panels? 
<Glass or acrylic - either will do, would use the one that's easiest to get your hands on.> 
I was thinking Plexiglas from Home Depot. 
<Sure.> 
Secondly, is there a silicone sealant that can be used underwater without adding any pollutants to the tank? 
<None that I would suggest - you should really plan on doing this work in a dry tank.> 
Or am I just going to have to drain the tank and use the sealant? 
<Yes... this is your best bet.> 
I know that your site recommends using 100% silicone sealants without additives, will the silicone package say that it is aquarium safe or am I just to assume that it is? 
<If you pick up the silicone from a local fish store, you should be all set... even though Home Depot does carry silicone that will do the job, they have too many tubes of the wrong kind that would be too easy to grab. There is such a thing as "aquarium sealant" that can be obtained at your LFS.> 
Thank you again for your help.
<Cheers, J -- >

Acrylic tank question
Hello,
I am building my own acrylic tank, the dimensions are 48"W x 96"L x 48"D. Is 1" - 1 1/4" acrylic sufficient enough to hold water?
<Mmm, well... it is... but... if this is for a "fish tank" and there are no really pressing desires to make it this tall... I'd cut the height down to three feet or so... much easier to work on... and whether the setting is high/low (standing, sitting), a better "dimensional aspect" IMO... the tank will bow pretty noticeably even if braced... and from your website am sure you are aware of the cost difference between the one and a quarter... or what I would use here (if going with the four foot height), one and a half... Worth it... structurally and from a resale point of view. Bob Fenner>
Thank you for your prompt response.
Thanks, Bob North
Please visit us at: http://www.splashescreative.com/ 
<Neat!> 

Re: acrylic tank question
Bob,
Oops!  I made a mistake. This is a prop to be used for a magic illusion however the dimensions I gave you were wrong. The correct dimensions are 48"W x 96"L x 96"D. We are committed to the 8'depth dimensions and cannot waiver from this. (I've already talked him down from 12'). We will be using full 4'x 8' sheets of acrylic. Do you think that the 1 1/4" thickness will hold water and the magician without bowing or breaking?
<Not worth the risk. Our old companies used to fabricate acrylic aquariums (in addition to other work)... and for any tank of eight foot depth I would NOT use less than two inch cast>
What thickness would you suggest?  I appreciate your promptness.
Thanks, Bob North
<Do a bit more looking about... but, please... no less than two inch. Bob Fenner> 

Appropriate acrylic adhesive for reef tank
Hello,
<Hi there>
I purchased an adhesive (Devcon Plastic Welder) for my DIY skimmer and I have a quick question regarding any problems with this adhesive.  Will this adhesive leach any harmful chemicals after it has cured 24 hours?  Any input will greatly be appreciated.  Thank you.
David
<No worries... their MSDS: http://www.tapplastics.com/uploads/pdf/MSDS%20Devcon%20Plastic%20Welder.pdf
Once cured there is none left... not a glue... but a solvent. Bob Fenner>

Acrylic DIY supplies 6/13/05
Hello, I've been searching on your site for some recommendations for acrylic or plastics.  I want to make a black acrylic box open in the bottom and top with a slot in the middle to hide my Turbelle pump in the aquarium.  The question I have is where can I find a supplier?  Are the easy to find where I live, Dublin, CA or is there one you can recommend on the internet?  I'm looking for the black acrylic.  Thanks, Brent
<Most major metro areas have an acrylic supplier.  Check your local yellow pages under "plastics - sheet, rod and tube".  If you don't find someone local, do search for the websites of commercial plastics or US Plastics.  Both sell retail online.  Best Regards.  AdamC.>

Acrylic aquarium construction 7/14/05
I don't know which is the best way to hold the acrylic pieces together in order to glue them and construct my acrylic aquarium. Could you help me? Thanks. Giannis
<Building acrylic aquariums is generally NOT a do-it-yourself project.  Special solvent cements are required, and the joints between the panels have to be perfectly machined to fit.  There are specialized techniques for using spacers in the joints to allow the cement to enter the joint, and then removing the spacers to make a perfect seam.  Clamps and jigs must be used to hold the panels in place until the cement cures.  I strongly suggest doing a lot of research or leaving this project to the professionals.  Best Regards.  AdamC.>

90 gal aquarium
Hi. Like to say that there is some great info on the site.
<thanks kindly>
Im in the process of scraping some money together to build a 90 gal saltwater aquarium. I plan to make it out of 1/2" acrylic. Dimensions of 48"x18"x24".
Calculator says it should be about 90 gals. Im also gonna glue in a top brace for added support.
<will certainly be necessary. And are you working from specs with deflection tolerances of the material that you've bought or are you just building a hand grenade? <G>>
My question is, can I build a 180 gal with the same materials and same dimensions except the width being 36"? 
<While I am not an expert on acrylic, I can tell you that glass aquaria wider or taller than 30" cannot safely be built without a four sided capture (welded angle iron/steel, etc). And since 1/2 glass suffers less deflection than acrylic, a 180 will 1/2 acrylic is unlikely to be sound without very intrusive bracing if at all>
I'd like to give my silver Pacu a little more room to grow in.... What do you think?
<I agree... the Pacu needs much more room. Anthony>

SMALL DIY Tank
Dear Bob,
Most of the help I can find on the web is for REALLY large DIY tanks. I am interested in constructing an equally small one.
I am trying to go the least technical route b/c I have limited experience with tools but always want to try.
I would like an aquarium about 10"d x 18 or 20"l x 10.5"h, and I would like it to be lighter than glass and moveable (not while full of water). This is kind of like a short 10 gallon-- Not an available aquarium size.
<Okay>
I am wondering if I could make such a tank out of 1/4" Plexiglas, with a wood frame.
<Yes, could be done>
From what I've read, I understand that the plexi-to-plexi bonding would require something like Weld-On.
<Yes, or similar solvent>
What about bonding the plexi to the wood frame?
<Only for looks in this size, shape system. You could use a smear of silicone to hold the wood together and to the plexi>
Or is a frame not necessary for strength of the Plexiglas?
<Correct>
If my project is even possible, could you please help with a general description of the steps that should be taken in constructing a small tank with plexi and wood?
<Measure, cut the pieces, tape or clamp the pieces in relative place, squirt/place the solvent... let cure for a day...>
I can handle plexi, glues, wood, staining, nails and screws, but I'm afraid I have trouble with anything much more technical than that (marine plywood, epoxy, fiberglass tape...).
<Not necessary to be/get too involved>
Thanks so much for your help. Your website and FAQs are really helpful. I hope I can do you proud :)
<You have my friend. By being, expressing yourself. Bob Fenner>
Jill Petersen
Atlanta, GA

Building Acrylic Tank
Dearest WWM Crew,
<Hi Shawn>
The best piece of advice I got when I asked about beginning in the marine aquarium hobby was READ READ READ. Thanks to your site I haven't had to go far to log over 100 hours of reading just on your site in the last two weeks.
I've kept fresh water tanks since I was a young child and have been very successful at it, breeding everything from livebearers to some quite difficult tetras.
I've decided to start with a small semi-reef environment to experience the basics with plans to build a much larger than normal system in the next year. My problem arises with probably what I figured to be the most basic of formulas and was hoping that since I haven't found it anywhere else on the net or your site that maybe in your all-but-omnipotent knowledge someone there might be able to help me out. Is there a specific mathematical formula for finding the pounds per square inch exerted by salt water? 
I hope that made sense, lol, I know that water as it pertains to aquariums exerts more force on the top of the aquarium as opposed to the bottom, my problem is finding a formula for figuring out what material tensile strength I need to build a specific sized aquarium...any help you could offer would be greatly appreciated. Sincerely Yours, Shawn King, AKA reefrookie
<Yes, there is a formula for figuring out the thickness the material should be based on the height, length, etc. These formulas are specific to the various types of materials, glass, acrylic, etc, and subgroups of these based on formula or proprietary differences.
Many of the acrylic manufacturers offer product fact sheets containing this information as it is specific to their material. I would start with the manufacturer of the material you want to use. Craig>

Acrylic
Hi guys, quick question. I am in the process of making an acrylic sump. Had everything cut.. sides, dividers and have all the glues ready, but I screwed up a couple pieces tonight trying to take just a little bit off the sides (and now I need some new pieces),!@##*...bad night. Here lies the problem.
There is no place in my town to get the thickness I was working with. So I had to order everything to begin with. My sump dimensions are... sides 30"x16" and the ends are 16"x16". Was using .177" or 3/16" acrylic and even had some 1/4 from another time. The only place that sells acrylic has it in .100" or 1/10" do you think this is to thin for my sump?
<Too thin for me... unfortunately... not enough bonding surface... and will bow too much... I would hold off till you have the 3/16" material>
Will still use 3/16 and 1/4 baffles/dividers, probably 3 of them in the sump. Let me know what you think. Thanks again, Bryan
<Patience my friend. Bob Fenner.>

Building acrylic tank
I just found your site and have been looking around it. Very nice, I plan on looking more.
<Okay>
I was trying to find a formula on how thick to make an acrylic tank. I noticed in the /dessysfaq2.htm page you talk about 1/2" vs. 3/4" on a 24" tall tank. I've got an idea for a tall tank, but not sure how thick to make. I had a few companies quote the tank but some say 1/4" some say 1/2". I understand about the bowing being reduced with thicker material but eventually there must be a minimum thickness decided by a formula.
<More like "general guidelines... there is some "fiddling" with these rules of thumb depending on a few factors... length, earthquake proofedness, surface/top bracing... quality of material used (this does vary)... I would likely go with 3/8" and maybe opt for a bit thicker material for the bottom... 1/4" will bow too much... and thicker all the way around is too expensive/rich for my blood>
Can you tell me where I can find this formula? Thanks, Steve Larson
<Due to the litigiousness of this society, I doubt if anyone will/can refer you to such... I'd check out the systems made for resale, go with at least what they are made of. Bob Fenner>

My Acrylic Aquarium
Dear Wet Web Crew,
I am discouraged.  After reading today's FAQs, I am concerned that my new acrylic aquarium is under-engineered.  My 110"L x 45"H x "38"W
aquarium is being constructed with 1" acrylic walls (7/8" actual thickness), 1/2" bottom, 3/4" top.  Bob's advice was to use the same material thickness for top/bottom as walls.  Further search for FAQs on acrylic aquarium construction lead me to conclude that 1" material may be inadequate for 45" height (salt aquarium).   
<Mmm, I would have upsized the bottom... and looked into the cost of thicker material for the sides, front, back>
Is this design unsafe?
<Likely will be okay if placed on a good (strong, planar, level) stand>
Am I going to be faced with excessive bowing?  
<Subjectively... up to you to decide. If you're mainly going to be viewing head-on, likely not too bad>
The top has not yet been glued on, so still have an option to reduce height (although I'm sure at great expense).  What is the maximum recommended height for 1" acrylic?   
<About four feet... the bowing question is a matter of the "run" (length) of the system as well as height>
I'm hoping for reassurance that the existing design will pass engineering muster.  At this point, safety is a greater concern than bowing - but I really need frank advice.
<Should be fine. Bob Fenner>
Thanks in advance.  
Steve

Re: My Acrylic Aquarium (stand)
Bob,
Thanks much for your reply.  Making this kind of investment is unnerving.  Your response is reassuring, but I can see that I now have
more work ahead of me to ensure the provision of flawless base support (stand).   
<Yes, absolutely critical.>
I plan to use a single layer of concrete foundation block for the stand with 1.5" of plywood between block and tank.  Concrete blocks will
provide contiguous support under tank accept for areas where 4x1.5" bulkheads and associated plumbing run the length of the tank.   
Bulkheads are planned to be cut near the edges of the tank (leaving about 2" of material between holes and edges).  Any concerns here about
stand or about placement of bulkheads?
<This whole apparatus is set on a concrete foundation? I would use a "water level" (the tank itself) to make certain of its planarity. Please see here: http://www.wetwebmedia.com/tksstds.htm>
  Given my 1/2" thick bottom, am I introducing significant additional risk by cutting holes for bulkheads?
<Yes... If this tank has not been assembled yet, I would have this bottom made of 1" material. Much to say here... IF a tank of your dimensions was built with the sides, front and back panels atop (as opposed to on the sides) of the bottom, this would not be such a concern... but cutting through the bottom for throughputs, and having to leave space around these to fit plumbing... makes me uneasy. Our companies used to fabricate acrylic aquariums as well as installing hundreds made by others... in Southern California... where the ground shakes occasionally. I like to shy on the conservative side here. I would either NOT drill the holes in the bottom (and instead make them near the top back edge) OR secure a thicker bottom. Bob Fenner>
Thanks again!
Steve

Re: My Acrylic Aquarium
Bob,
I am grateful for the advice.  The four walls of the tank are 'resting' on top of the bottom and are glued in this fashion.  Given this assembly technique, would bottom holes be acceptable?
<Not for me>
  Could I reinforce around the bulkhead underneath the tank by gluing an additional 6"x6"x1/2" plate (thus creating a 1" section in places where the bulkheads pass through the bottom)?
<Unfortunately no. Have seen this tried time to time... too much likelihood of these added pieces joints failing. Bob Fenner>
Thanks and regards,
Steve

Re: My Acrylic Aquarium
Bob,
Thanks yet again for your response.  I see your point, and I have resigned myself to the fact that the meager thickness of the bottom leaves me with no alternative but to formulate a different approach to plumbing.
<Yes... this tank will hold some 825 or so gallons... with water weight of 6,600 or so pounds...>
If you have any patience remaining for me, I'll share a bit more detail about my original design, offer a possible contingency in light of the
issue above, and then leave the door open for any suggestion(s) you might have.
The aquarium is designed to fit an available space in my home.  I am dividing an unfinished storage room in the basement with this aquarium.  Walls will be constructed to frame the aquarium, and one half of the space will be finished as the viewing area for the aquarium. The other half of the room (behind the aquarium) will serve as the pump room, filtration area, work area, etc.
<Good idea to have plenty of space.>
The visible area from the viewing room is 9 feet (but an alcove area actually extends several feet beyond the viewing area).  Given that my local aquarium manufacturer was charging me for full 10 foot sheets of acrylic, I decided to build the aquarium 10 feet long with a 1" acrylic wall divider at the 9 ft mark and a second 1' wall at the 10 ft mark.   
The intent here was to use the last foot as a sump that would enable me to draw water from the bottom of the tank, flow into the bottom of the sump, and then overflow into pipes 1-2" below the surface of the sump (i.e. tank water line).  This would allow me to effectively circulate water to the bottom of the tank, draw unfiltered water from the place where waste and detritus naturally accumulate, and achieve the benefits of a surface draw without any visible pipes or plumbing in the main tank.  If I spring a leak in my plumbing at any point down-stream, the tank will not drain below the level of the surface feed pipes.  The only risk to the system is obviously the plumbing connecting the main tank to the sump (a leak here will drain the tank).
<Yes>
Original Design:
My original design was based on a UG filter to draw water down through a course gravel bed and out bulkheads distributed evenly across the bottom of the tank and deliver water to the aforementioned sump.  In previous dialogue, you encouraged me to avoid using UG filters and guided me towards a sand bottom.  Many hours spent mulling through your FAQs helped me clearly understand the logic of your recommendation and convinced me a redesign was in order.
Redesign #1:
Your recommendation to use a DSB now seems like the optimal choice.   
The height of my tank (45") leaves plenty of room for the DSB.  I still wanted to incorporate the principle of drawing unfiltered water from the bottom of the tank, so I repositioned the location of the bulkheads from the center of the tank to back perimeter.  I designed a simple acrylic box structure (full length of tank, 5"W, 4"H) that will rest on the bottom of the tank, butted up against the back wall and resting over the (4) 1.5" bulkheads.  A small 1/8" opening runs along the full length of this chamber and protrudes above the DSB to draw water across the DSB, down into the chamber, out the bulkheads and up into the adjacent sump.  Bulkhead location in the bottom of the tank seemed optimal because it would ultimately suck out any detritus that settled into the chamber.  Keeping the chamber to the rear of the tank drove the requirement of locating the bulkheads as close to the edge of the
tank as possible.
Today's dialogue has again exposed flaws in my design. Drilling through a 1/2" bottom plate will push the limits of a marginal design. Anything short of full, stable support for a tank weighing 7,000 lbs, resting on a 1/2" sheet of acrylic is unwise at best - plumbing underneath is out.
<Yes>
Redesign #2
Where do I go from here?  I would still like to draw water from the bottom of the tank.  I would like to maintain a very clean tank interior (no visible bulkheads, stand pipes, etc).  I could keep this chamber concept alive by simply shifting the bulkheads to the rear wall (as you suggested) but my objectives above would require me to drill holes for the bulkheads leaving only 2" of material from the bottom edge of the sheet.  1" thick acrylic makes this less of a concern than the 1/2" sheet, but is it still to be avoided?
<If practical. You could run plumbing for the main tank intake inside the system... with just one pipe (that you'd have to prime and cap... coming up, over the wall of the in-tank sump... But I encourage you to consider yet another possibility... of using space behind the tank for a much larger sump... having the water exit from thru-hulls in the sump area (if you'd like) with overflow and near-bottom draw of water to the sump from the tank... and batch processing, treating the water in the external sump... the internal one is going to be too much trouble (1' width is a pain to get in/out of as you'll see) and the circulation you'll want will be too much to draw in and move through it.>
Is the concept of drawing water from the base of the tank to maximize the removal of waste and detritus valid?
<Yes... but dependent on many other factors>
Does my design concept of using a chamber buried within the DSB to unobtrusively draw water to the sump have a chance?
<Not IME>
I am open to rethinking the whole water flow design concept and would gladly leverage any learning's from your training and experience.  Of course, the tank itself (dimensions, material thickness, sump) offers little flexibility for change as it is essentially complete (small consolation - no holes drilled yet).
<I see>
I obviously should have done more homework before I started this project - I thought I knew more than I did.  Spending 10 years in the
marine hobby from 1976-1986, with 5 years working for a LFS, helped me learn a lot, but that education seems to be about as useful today as my
father's slide rule.  "My how things have changed".
<Yes>
I've learned a tremendous amount over the past month, thanks to your website and all of the resources present, not the least of which has been your personal council. I've read Paletta's book and have yours on order. I'm playing 'catch-up', and intend to learn a lot more before this aquarium is officially launched.
<You'll do fine>
Again, thanks for your ear and for your guidance to date.
Regards,
Steve
<I wish you lived close/r to San Diego... we have a hobbyist club here with folks that have large systems as yours... who have gone through similar approaches, trials... You could simply visit with them, see what they have done. I would abandon the current design, and add a large external sump (like 200 gallons... like a polyethylene tote...) and likely drill the tank, attach street elbows to the bulkheads (to adjust overflow of the main tank height... and do some dreaming, scheming re pump choices... Bob Fenner>

Re: My Acrylic Aquarium
Bob,
Again, thanks for the advice.  Living in San Diego certainly has its appeal - its a bit warmer than Minneapolis this time of year.....
<Brrrrr~>
An additional external sump makes sense (fed from the small sump attached to the main tank).  I also like the idea of feeding water from the main tank directly to the small sump through the dividing wall (surface overflow and near bottom draws). At this point, you've got me convinced to get rid of external plumbing all together, if possible.
<Ah, good>
Is there any benefit to drawing water from near bottom on both ends of the tank (accomplished by running a piece or two of 1.5" PVC under the
DSB from the far end of the tank into the small sump), or is drawing from only one end of the tank adequate (nine feet seems like a long
ways to pull from only one end).
<Better to not complicate things here... with sufficient water movement no worries re detritus accumulation. Do take a read through WWM's marine plumbing areas... starting here: http://www.wetwebmedia.com/pbfaqsmar.htm and on for much more input on possibilities. Bob Fenner>
Thanks and regards,
Steve

Re: My Acrylic Aquarium
Bob,
Thank you for your time and helpful advice.  This is a great website and a tremendous resource for the hobby.   
<Glad we have found each other>
I'm off to read up on plumbing, sump design,.....
<Ah, good. Bob Fenner>
Steve

Re: diy acrylic aquarium
Thanks Bob for the quick response re. my 72"x20"x24" acrylic thickness but it brought up more questions.
First, does it matter if the sides "frame" the bottom panel or can they sit on top of it?
<Better to build the sides, front and back on the bottom>
If they can sit on top, why does the thickness of the bottom piece matter if it will be totally supported as acrylic tanks should be) by the stand?
<Mmm, helps to resist shearing force... by uneven support underneath (the stand, what it in turn sits on)... the most force is actually on the bottom>
Does thinner material (3/8" vs. 1/2") "stretch"?
<Yes, to a small extent more>
I've already got the material and am trying to avoid spending any more $$ unless I HAVE to? My wife is rooting for no more material, but I think she will be much more upset if 150g hits the floor! Thanks again, Scott
<Agreed... if you haven't cut the sheet and the paper is still on it, ask the supplier to allow you to trade it in for 1/2"... This is what I would do. Bob Fenner>

Re: diy acrylic aquarium
One last question...for now. Do you know if it would be possible to purchase 1/4" acrylic and solvent bond it to the 3/8" to "create" a 5/8" thick piece for the bottom (as an alternative if the acrylic guy won't exchange 3/8" for 1/2") Or am I grasping at straws that don't exist!
<The latter. Bob Fenner>

Re: diy acrylic aquarium
I am making my own 72"x20"x24"h acrylic tank. I am using 3/8" for the bottom and 1/2" for the sides.
<I would make the bottom (and top, see below) at least 1/2">
I am planning on two 1 1/2" overflows that will be located in a 5"x20" overflow box built into one end as this tank is sitting on a partition wall and will be viewed from the other three sides. First, will these overflows be sufficient if/when I gradually progress to hard corals?
<should be, yes>
Second, I was planning on using 3/8"x3" strips of acrylic to make a rim around the top of the tank with three 3/8"x5" strips used as bulkhead
braces (front to back) spaced evenly.
<I would make the top one piece, route out the openings for access>
Will these "strips" be sufficient to reduce bowing or should I get a solid piece of 3/8" and make cutouts as is
commonly done? And is 3/8" thick enough for the top?
<Make the top, bottom, at least as thick as the sides, front/back. Bob Fenner>

How thick is thick enough? (custom tank construction)
Hi, I have read hours of great ...GREAT info on this site!. I am building My own tank and I plan to start next week. It will be plywood and acrylic (Plexiglas) the dimensions I would like to build will be 96" long x 24" deep x 48" Tall, I have priced all of the items to include the very hefty 1" thick sheet of Plexiglas.... BUT?? will 1 inch of thickness be ok? also will 1" thick plywood be enough? The rest I can Handle through the outstanding idea's and instructions in your site, Thank you very much, Sincerely, Michael Waszak
<Mmm, well... if this tank's viewing panel were braced all the way around it would do, but likely bow too much (to suit me)... I would increase the thickness of the plexi and paneling if it will fit your budget. Bob Fenner>

Re: How thick is thick enough?
Thanks bob, I have decided to change the tank size to officially, 96x18x48.   with the 4x8 foot plexi @ 1" thick. do you believe that the glass and 1 inch plywood wood with these dimensions would cut down on the bowing?
<These are the same dimensions as listed before (for the building materials)... the width (L X W X H) is not important here... the depth is. The "answer/response" is the same)>
( the master plan here is really a compromise, My wife Loves LONG! and I've always wanted a tall tank....) She plans on lots of smaller schooling fish. fish turning wouldn't be an issue (depth)......another question i guess would be should I drop down to 96X12x48? i really appreciate the time you give to help people like myself. I will send you a finished pic or 10 :-) oh yeah..It will be braced all the way around!
<I think we/I am confused here... the middle dimension you list is the height? You can easily have this tank three feet (36" in height made of these materials with little detectable bowing, risk of structural failure. Bob Fenner>
WHAT WE ALREADY DISCUSSED~
Hi, I have read hours of great ...GREAT info on this site!. I am building My own tank and I plan to start next week. It will be plywood and acrylic (Plexiglas) the dimensions I would like to build will be 96" long x 24" deep x 48" Tall, I have priced all of the items to include the very hefty 1" thick sheet of Plexiglas.... BUT?? will 1 inch of thickness be ok? also will 1" thick plywood be enough? The rest I can Handle through the outstanding idea's and instructions in your site, Thank you very much, Sincerely, Michael Waszak
<Mmm, well... if this tank's viewing panel were braced all the way around it would do, but likely bow too much (to suit me)... I would increase the thickness of the plexi and paneling if it will fit your budget. Bob Fenner>

Sump Baffles
Hi All,
<Hello>
I have a sump question.  I read an old FAQ about an acrylic sump a guy was making and he wanted to attach a few acrylic baffles in it.  Bob mentioned that as long as they are not structural, you can avoid using the Weld-on product and just use silicone rubber, the type you find at the hardware store.  I got some stuff from Home Depot, 100% aquarium use silicone, I assume this is what he meant?
<Yes>
Also, since I will be adding two baffles, one for the divider of the first chamber to the second which will go from the bottom up about 9 inches or so with water overflowing over the top, and another smaller one a few inches high in just in front of the bulkhead to the return pump to prevent bubbles or whatever else, I assume these are not going to be structural in any way.  They should be able to hold back the weight of the water without any problems, using only the silicone.  Is this correct?
<Correct. Give the Silicone a day to cure before filling the sump. Bob Fenner>
Thank you
Paul

Acrylic tank building
Hello to the greatest crew on earth.
<Howdy>
Couple of quick ones I hope, I am considering building my own acrylic tank.
Call it 48"L x 20"W x 24'H,( 100g ?). I was planning on 1/2" and wondered if a 3/4" x 1 1/2" solid oak frame around the top would be adequate to prevent bowing of the front/back.
<Should be>
Would you recommend any further front to back bracing?
<Yes. At least a brace front to back on the top... or better, a solid piece with holes routered out for access... solvented along the entire top edges... like production acrylic tanks>
Also I was planning on bending the front and sides from one piece, if I build a jig to secure the front could I bend the sides around a 3/4" dowel using a blow torch or would a heat gun be better?
<... careful here. I strongly encourage you to just "butt" the corners together for this system. The heating gear for doing bends is more involved... easy to ruin many sheets in experimenting. Do you live near a manufacturer, fabricator that does heat-bending? Do call, visit them first if you're still interested in pursuing bent corners>
I built my own 30g sump with 3/8 as well as my own overflow box with good success so I think I'm up for the challenge, any suggestions or pitfalls to look out for?
<Mmm, many... make sure your cuts are square, clean... maybe use more viscous (thicker) solvent...>
Also was planning two 1 1/2" overflows in back corners, would this be adequate for a 40 gallon sump.  I figured this would give me about 1400 gph?
<Okay>
As always your kind help is very much appreciated.
<Have you considered making such tanks for others? I sense a pet-fish entrepreneur here. Bob Fenner>

A Small Set-Back (catastrophic tank failure)
Hello, Bob.
Thought I'd share this evening's adventure with you and your readers.  
My project of the past 6 months suffered a slight set-back this evening.  In the process of filling my 112Lx38Wx45H aquarium with water for it's second wet test, it suffered a catastrophic failure.  When the water was about 4" from the top, I heard the dreaded sound of a very deep thud (sounded like ice cracking on a Minnesota lake during the spring thaw).  Upon hearing the thud, I knew immediately the tank had failed and I quickly turned off the water.  Within a few seconds the entire front 1" sheet of acrylic gave way and my surprised wife (who was down the hall) later described the tidal wave of 800 gallons of water approaching her with a certain amount of disbelief.  
<Oh no!>
I've spent the last several hours wet-vac' ing the carpet in the basement - probably getting up around 100 gallons.  The rest will wait until tomorrow morning for professionals to come with industrial sized vacs and fans to finish the job.  
<Money well spent>
Three flooded bedrooms and a flooded family room all have very soggy carpeting. Storage rooms have lots of soggy boxes.  The aquarium room has holes in the dry-wall where the 6'x4' chunk of broken 1" acrylic was swept 9' across the room and into the opposite wall.  The 9' ceiling is wet where the water hit the wall and splashed upwards.  The dislodged acrylic broke a leg on a 6' ladder that was in its path as well as crushing a metal chair.  I am grateful that my kids were not in the room watching at the time - injuries would have been likely.
<Have seen damage from such breaking tanks. Agreed>
The top failed at almost exactly the mid-point of the middle cut-out (not at a corner) which leads me to believe the front face actually failed first.  I measured almost 3/4" of deflection on the front pane during the first wet test.
<...>
On the positive side, the aquarium failed during a test run with clean tap water.  It could have failed somewhere down the road with 800 gallons of salt water, 1,000 lbs of aragonite sand, and with significant live stock in tow.  I choose to be thankful for the circumstances of today.
<You are wise here>
I'm off to bed.  Tomorrow is going to be a busy day........
Regards,
Steve Walker
<Will you rebuild this tank with thicker material... or perhaps "cut down the height with the 1"? Bob Fenner>

Starting Over (800 gallon acrylic)
Hello Bob and WWM crew,
<Hello Steve>
Following the failure of my 800 gallon aquarium two nights ago, clean- up is well underway.  Carpet has been pulled up, padding thrown out, baseboards removed, industrial sized fans everywhere, industrial sized de-humidifiers humming away.  It sounds a bit like the continuous drone of a jet engine in our house.
<Thank goodness no one was injured>
The cleaning service I hired suggested I was fortunate things are not worse and estimated that this will be a relatively quick clean-up that shouldn't take more than 7-10 days of aggressive blowing/dehumidifying to complete. I'd hate to be 'unfortunate' in this situation.
<Have seen, been part of some of these cases>
While much work remains to simply get back to the place where I started this project (not the least of which is carving up the remains of the
old 1000+ lb aquarium and hauling it away), my mind is moving towards thoughts of starting over.  
<Good>
My aquarium manufacturer is re-grouping and is preparing their plan for a second attempt at this aquarium.  I intend to be a bit more involved in the selection of materials on this go-round.  Your thoughts would be greatly appreciated here (and I fully understand that your thoughts do not constitute an engineering recommendation and should not be relied upon as such).
<Okay>
It is my desire to maintain the original design specifications (112Lx38Wx45H). The price of acrylic seems to rise exponentially as thickness increases beyond 1".
<Yes. It does>
I believe I will find a way to fund the leap to 1.25", but this will likely be my limit and may need to adjust my design accordingly.
<Okay. A comment re the cost of acrylic sheet... There is a "strata" of manufacturers, distributors, dealers... and fabricators can fit in most anywhere in this scheme... What I am trying to say is it pays to "shop around" for the materials here... There is a HUGE range of costs/pricing...>
If I hold to the plan of 45" height, have you observed aquariums with these approximate dimensions constructed with 1.25" acrylic that seemed structurally and visually sound?  
<On this run (length) of tank, the tallest I would go with one and a quarter material is forty inches... really. AND I would make the rest of the tank out of the same thickness... including the top and bottom of course>
If you would be willing to offer an opinion, I will further ask what you would consider to be the maximum height for 1.25" acrylic and 1.0" acrylic, respectively (while maintaining a healthy safety margin and acceptable visual appeal)?  
<There are a few stipulations (set on a flat, planar, level, strong stand... and that the cuts are clean, square... and the solventing done "appropriately"... and there is a factor for the length of the system... but all this taken into consideration, 36" height for 1" material all the way around... and forty inches for 1.25"... and for four feet of height... 1.5"...>
No worries if you prefer not to speculate on these questions.
<These are not speculations... our companies fabricated acrylic aquariums for several years (fourteen if memory serves)... and... yes, we tended to be overly conservative... as many of our sales and installs were in California (where the ground shakes considerably at times)... or sold to "unknowns" that might have not done quite as conscientious a job in some way/s that might compromise the structural integrity of our tanks...>
  I understand they are better suited for the manufacturer - but nothing beats the opinion of an experienced and trusted aquarium fabricator.
<Agreed>
Thank you again for your valuable website and for your willingness to provide capable assistance.
I remain gratefully yours,
Steve
<A pleasure to share, learn. Bob Fenner>

Re: Starting Over -
Bob,
<Howdy, Bob is in Brooklyn giving a pitch, today you get JasonC instead...>
Thanks very much for your candid advice on acrylic thickness for my large aquarium re-design. <Indeed, what a story.>  
Given the recent catastrophic failure of my 800 gallon aquarium, my tolerance for risk is gone. <I don't blame you.> A conservative design with an ample margin of safety is the only approach that will suffice - not only for my own well-being, but for my wife's as well - recognizing that I need to regain her trust and support before I can, in good conscience, move forward with another attempt. <I hear that.>
Negotiations still remain with my aquarium fabricator regarding the losses I have incurred, but hope to quickly put that behind me and focus my energies on plans for a (safe) 40" high aquarium using 1.25" acrylic. <Do consider building in a margin of safety, either go with thicker material at that height, or lower the height - just to add to the fault tolerance.>
Until that time, I hope to make good use of my second chance at designing my system.  More reading, dreaming, planning. <Sounds good.>  
Best regards and deepest thanks,
Steve
<Cheers, J -- >

-Starting Over - Large Acrylic Aquarium Design
Hello Bob,
In our last correspondence, you recommended a thorough search of acrylic suppliers to find the most reasonable price for 1+ inch acrylic.  I was amazed at what I found.  1 and 1/4 inch stock varied in price from $570 to $960 for 4ft by 8ft stock.  Do you believe the quality of the materials offered varies enough to account for (or contribute to) these price differences?  
<Not likely. More a matter of price differences due to lack of competition>
I have modified my design/expectations to accept a shorter run length of 8 ft, instead of the 10 ft used in my original (failed) design.  I intend to use 1 and 1/4 inch material everywhere.  My design is intended to maximize volume with available 4'x8' sheet stock - 96"L x 48"W (possibly a bit narrower) x 40"H.  My question is as follows:  If 40" is the maximum safe height for this material, does the 40" limit represent the true height of the water column, or the combined height of base + walls + top?
Put another way, if I use 1 and 1/4 inch base and top, are 40" Walls acceptable (resulting in total tank height of 42.5")?  
<Yes, this last>
Thanks again for your assistance.
Best regards,
<Bob Fenner>
Steve

Acrylic questions
Bob,
A couple of questions for you regarding acrylic and its use in sump/tank construction:
1) What type/brand of acrylic would you recommend for aquarium construction.
There are many types: Plexiglas, Acrylite, Optix, etc, and I'm not sure which one (if any of these) are appropriate for aquariums (i.e.. transmit PAR light, maintain rigidity-avoid warping, avoid discoloration, etc).
<Hmm, actually most acrylics are pretty much the same. What people call them are more brand names then different formulations. I am a big fan of Reynolds as a manufacturer...>
2) What type of acrylic cement is best for capillary bonding acrylic in aquariums (Weld-on#3 ?).
<Weld-on for sure... Number three is okay... look for/use a "gel" type if this is one of your first tries at making acrylic anything>
3) What type of acrylic would you recommend for filtering UV while allowing other light to transmit freely (esp. PAR).
<Again, just whatever type you can find that is reasonably inexpensive of about the right thickness. I would not transmit "useful" light through the acrylic... shine it directly into the water>
Lastly, I've found a fluidized bed filter used in the shrimp aquaculture industry that's rated at handling 2 lbs of shrimp feed per day. Any guess at how much raw live rock this filter could handle if I used it in the curing process - along with heavy skimming (i.e.. skimmer output set to 5 times the number of gallons of water, with 1 gallon of water per lb of Fiji rock in the curing tank).
<A guess is "a bunch"... Shrimp are very dirty animals to culture... I'd guess if the folks who engineered this are saying "two pounds of shrimp feed", this equates to hundreds of pounds of live rock. Really. Bob Fenner>
Thanks!

Acrylic
Real quick. With acrylic to glass contact, the 100% silicone I have read about in the F&Q's will work right?
<I wouldn't trust it for aquaria... but for little troughs/trays/filters...maybe>
And definitely for acrylic to acrylic. 
<do use proper acrylic glue for this>
About cutting acrylic for bulkhead fittings. I have hole cutters for doors and such. this will work fine,
<yes if sharp>
and put the silicone on either side of the bulkhead and let stand 24 hrs. 
<OK... but neoprene gaskets that come with many bulkheads compress nicely and are more reliable>
Great job guys, Bryan.
<thank you kindly, Anthony>

DIY info
Hello
<Cheers.. Anthony>
Do you know were I can get some info. on building a acrylic self-contained tank with a sump and skimmer all in one. Thanks for your help and your time. Frank Thomashefsky
<many places on the Web... please try the DIY link on www.ozreef.org best regards, Anthony Calfo>

Aquarium manufacture
Bob, 
I live in Australia now and I noticed that all the aquariums for sale here are glass. I am wondering how hard it would be to set up a small facility to manufacture acrylic aquariums. 
<Not hard. A few thousands of dollars on the low end to a few tens of thousands for more serious investment, production>
Do you know much about the manufacture of aquariums or do you know anyone that I could contact by e-mail who might know? 
<We used to fabricate up to two inch thick acrylic tanks. Have several friends in the trade who do this>
I need information on how the front piece is bent, jigs and fixtures for manufacture, on exactly the type of plastic used (do they use regular acrylic or is it coated to be scratch resistant?),
<Not coated... some "brands", makes are a bit more scratch resistant, none totally>
the thickness of plastic for various sized aquariums etc.. Do you think it would be possible to set up a manufacturing facility? 
<Possible, sure>
I think that it would be too expensive to import the tanks because they take up so much space, and the Australian dollar is very low so anything from the USA is too expensive. 
<I do understand this. We're headed that way for a few weeks next month. Land, food, diving... a bargain>>
I like the pictures that you send out every day.
<Ah, am glad to hear> 
Good luck, Mike Sweet
<Mike, a very good idea for you to investigate, invest your time if serious at this point. Here on the West coast of the U.S. or the U.K... (where friends are who will help), to learn first-hand what is involved. Let us keep talking this over. Bob Fenner>

Aquarium manufacture
Dear Bob,
I knew you a long time ago at the fish club in San Diego. Currently I live in Australia. 
<Ah yes, you lucky pug. Which part?>
I have noticed that most of the aquariums for sale there are glass and look like they were made in someone's back yard. I was wondering how hard (and expensive) it would be to set up a small facility to build acrylic aquariums. 
<Not too hard... considering/stipulated you can secure the sheet, solvent to meld... and relatively simple tools (for a small volume of business) like a table saw, blades for cutting plastic, clamps, propane burners for burnishing...>
Most of the small aquariums for sale in the USA have bent corners instead of glued corners. Is that for looks or for some other reason?
<Mainly looks... (though time to make tanks reduced, a bit stronger... like castle keeps.) heat-bending is simple once you have the heating gear, jigs made up, timing down...>
I think that it would be too expensive to import aquariums to Australia from the USA due to the low value of the Oz dollar.
<How about the cost of acrylic itself...? And is there some sort of market currently, one you could hope to create... within a few years?>
Do you know anyone I could contact about this subject? I will be in the USA until December 29.
<A bunch of folks... who would likely help you themselves. Please contact Craig DeWalt of CASCO/SeaClear: c_dewalt@seaclear.com, check out their site, www.seaclear.com on the net re your wishes, visit. We are old friends/associates... make that middle-aged ones, so please do mention my name.>
Are you still living in Mira Mesa? 
<Yes... moved a whole couple of miles to the north recently... sigh. But we're hauling down to the "land down under" this March...>
I was in Fiji two years ago and went out diving with Walt Smiths' collectors a lot. They were very friendly to me. I heard that you came out to give a talk. 
<Yes, folks so nice they put up with even me...>
Unfortunately, I couldn't attend. I hope that all is going well with you. I like your
web site. 
<Hope to dive with you soon! Bob Fenner>
Mike Sweet

Acrylic Thickness
Are there any guidelines to follow when building an acrylic aquarium or for a 90H measurements of 48x18x24 what would be the acrylic thickness needed? Thanks
<Yes... some for structural strength... at least 3/8" (with an annealed top that serves as a brace), better 1/2" for the sake of cutting down of deflection/bowing. Bob Fenner>

Acrylic Thickness
I am looking into building an Acrylic Aquarium with the following dimensions: L=48" X W=24" X H=20" which will have a capacity of 100G. What would be the thinnest Acrylic I could use?
<1/2" with a capture/top piece.>
I would like to use 3/8" (.375 in) if possible as I can get a good price on 48"X48" sheets. Gregory A. Maher
<I would build a smaller tank. Something in the 36" long, 30 gallon range. -Steven Pro>
<<RMF thinks the 3/8" would be fine here... used for this height tanks in the industry>>

Most Everything You Ever Wanted To Ask/Know About Acrylic Aquariums
Dear Bob, I have tried to put all my questions in one list. Can you help me with any of these? Thanks for your help. Mike
<<Greetings, Mike. JasonC here, and I will do my best... >>
1) What thickness of acrylic is used for 20 gallon, 50 gallon and 100 gallon tanks? 
<<Well... the answer depends on the actual dimensions of the tank. On a general rule of thumb, perhaps 3/8" for a 20 up to 1/2" for the 100 - if there were one long panel, perhaps 5/8" or up to 3/4" for larger tanks. Probably best to break out the calculator and the acrylic manufacturer's spec sheet and do some homework.>>
2) Are the top, bottom and sides of the tank all the same thickness?
<<Again, this depends on the desired dimensions of the tank. The safe assumption is that IF you are making a perfect cube, all walls can be the same thickness. If you start stretching the cube into a rectangle, then the assumption changes.>>
3) Do they use regular acrylic glue or a special glue?
<<As far as I know, it's a standard acrylic glue - creates a molecular bond.>>
4) Are the corners bent to a different radius for different size tanks?
<<Corners are bent to a different radius for different thicknesses of material and visibility.>>
5) Can a small tank be made that has glued corners instead of bent corners? <<Sure.>> 
Why are bent corners usually sold? 
<<Easier than jigging up and adhering four walls with perfect 90 degree joints.>>
5.5) What is the radius of the bend of 20, 50, and 100 gallon tanks?
<<Depends on the material.>> 
6) Is the radius of the bend for strength or for looks?
<<Both... the material would maintain is strength for a while beyond a bend that ceases to look clear.>> 
7) Is the acrylic bent on a specialized machine or is it heated with a local heating element and bent over a mold?
<<Depends on the application. On smaller panels, I have seen a blow torch used. On larger, curved aquariums a large walk-in oven is used.>>
8) Can the acrylic be trimmed to fit after it is bent or does it have to be bent perfectly?
<<Well... the whole job has to be done perfectly. Cuts, joints, bends, you don't really get a second chance on the same piece of material.>>
9) Is it very hard to bend acrylic over a mold and get a perfect bend?
<<Let's just say that it is a skill, and one that can be learned. But not so simple that you'd get it on the first try.>>
10) Are there any special tricks that you know that help in bending the front piece of acrylic? 
<<Patience, lots of patience, that and a fairly exacting eye for detail.>>
11) After the front piece is bent, are there any special difficulties gluing on the top, back and bottom? 
<<Well, you want the thing to hold water... it's not as easy as it might seem.>> What order is best? 
<<Probably front to the back, and then that assembled piece to the bottom.>>
12) Have you heard of someone setting up a small shop to make acrylic aquariums? 
<<Uhh... Jason Kim of Aqua C comes to mind. He makes a fine line of protein skimmers, but also makes custom tanks and sumps. If I'm not mistaken, he started out as a one man operation. His skimmers are quite popular, and so he's not a one-man-show any more.>>
13) What fraction of aquariums sold in the US are acrylic now?
<<Couldn't tell you... but a quick mental survey says: depends where you live. If you live in an earthquake zone, you might not have a choice. Acrylic tanks are more expensive than their glass cousins so income plays a factor.>>
14) What is the difference in wholesale price of glass and acrylic aquariums in the US? What is the difference between the internet price and the wholesale price? 
<<I really don't have that information. You'd do best to ask the actual wholesalers and retailers.>>
14) What are the major advantages of acrylic? 
<<Two come to mind... acrylic is a better insulator. That and it is also much more clear than glass tanks which become more green as the glass gets thicker.>>
 Disadvantages? 
<<There are three disadvantages. One, price - acrylic tanks are much more expensive than glass tanks of the same size. Two, acrylic is easy to scratch and it's easy to do with a large chunk of live rock. This also means you need special cleaning pads. Third, and if you keep a reef tank, coralline algae has a strong attraction to plastics, acrylics included. This means that you either need to clean the viewing panels constantly, or go after them with special scrapers when you can't see the inhabitants any more like I do ;-) >>
15) Approximately how many manufacturers of 20-100 gal stock acrylic aquariums are there in the USA: 5, 10, 25? 
<<That's a good question, but I just don't know the market that well. I'd bet there are more than five, but not 25. Maybe more than 10 but not many more. Just a guess though.>>
16) Is it better to use a router, table saw or a panel saw to cut the acrylic?
<<A precision table saw with special blades for cuts. Router for cleaning the edges. Hope that helps. Cheers, J -- >>

Building an acrylic aquarium I was wondering if you could help me with a few questions. I am thinking about building an aquarium about 55 gal or so and I have read many articles about what thickness of acrylic to use for what height aquarium and so forth. I was wondering if you could use thinner acrylic if you were to frame the tank with a plywood box. (please see attached drawing)  <Not really... the thickness should be about the same or the same per height... If this is a "typical" 55 of 22" height (or even twenty inches), I would opt for a minimum of 3/8 inch (even half if you can afford it)... the bracing may well help to prevent bowing, even breaking... but the mid front and back will bow badly and result in noisome distortion if you try 1/4... or yikes, less thickness> For example, could you use 1/4" acrylic on a 24" high tank in this manner. I have also read about the wood and glass tanks but I would like to keep at least 3 viewing sides open. The wood I could get free and the 1/4" acrylic costs significantly less than the 1/2" so I figured I'd ask someone else what they thought before I flooded my garage. If it is possible to do this how substantial do you think the frame would have to be? Thickness of the wood 5/8 or 3/4? <Not really practical here... though I have made many (hundreds years back) of glass fronted (and you could make cut-outs for the sides as well) and plywood, resin and fiberglass (stripping is best here, pre-made and available in rolls) tanks... with 3/4 and 1" ply and good brass screws (2 1/2 or three inch)> and how much of the viewing area would I have to cover? <For the glass et al. structures, a good three or four inch edge is good all the way around> Would it be a good idea to pad the inside of such a frame and to give it rounded edges? If it did work it would then be very easy to incorporate a nice wooden hood. Thanks for you time, Great website! Christopher C. Hehn <I like the way your mind and writing presents it/themselves... do keep investigating. Maybe Oz' Reef: http://www.ozreef.org/ Great, one-stop DIY site for pet-fish types. Bob Fenner>

Plexi glass glue
Hi there once again,
I have a question about the type of glue people use to put together plexi glass. 
<Most folks use a commercial acrylic solvent... like Weld-On>
I hear that the best way to glue two pieces together is to use a solvent called Methylene Chloride. 
<This is a principal ingredient. Toxic, flammable, not generally available to the public.>
can't seem to find it in Home Depot or Lowe's. Do you know where it might be available? 
<Check with the businesses listed in your phone directories who sell or do plastic fabrication>
I also wanted to ask if you know whether this solvent (Methylene Chloride) can be used to glue plexi
glass+regular glass together, or is it just for plexi glass+plexi glass?
<Only the latter>
On another note, I'd like to thank you for responding so quickly, and for being real informative. It's advise like this, that I wish I had for everything I come across. Your help is greatly appreciated. Thanks, Hamilton, Riverside, CA
<Glad to be here helping. Bob Fenner>

Re: plexi glass glue
Thanks for your help, but I'm not quite sure about what you meant by (only the latter). 
<The last statement... these solvents are only for acrylic to acrylic bonding>
Can you describe this in another way? And is (Weld On) safe for fishes. Well I guess it is since you said everybody else uses it. Thanks for your help.
<Safe after cures (a day or so)... it actually "leaves"... melting/melding the Plexi as one piece. Bob Fenner>

DIY Acrylic Tanks
Hi this is Abraham, my first time here. I'm looking to utilize acrylic sheets for marine fish holding systems. My question is how do you cement the sheets together, meaning which material is aquarium safe? In addition, which silicone sealant is aquarium safe? One more question, how do you figure the thickness needed of the acrylic sheets needed for reservoirs for the sump tanks? I understand that it depends on how much water is being held in one given place. So for instance, a holding system of 8 feet long by 2 feet wide and making several of these units tiered one above the other in relatively shallow pools, no more than a foot high. For example; what thickness of acrylic sheets is minimally needed. Understandably braces are needed on top as well. Please try to help me out with this as soon as you guys can. Thank you and I am gratefully appreciative of your time and efforts.
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Acrylic Wall Thickness for Large Tank 7/17/04
I am building a very large tank in the shape of an equilateral triangle.  The dimensions are 24 feet long by 8 feet to the point of the triangle by 4 feet high (or deep).  It will be placed on a strong 18 inch concrete floor.  I am guessing that 2" for the sides and 1 inch for the top and bottom should hold well but I am just basing that on my limited engineering experience.  Do you know how I could find out if these dimensions will be OK.  Can you recommend any structural engineers if I need one or is it not that complicated if I know how to figure it out.  Thanks Dimitrios
<Hi Dimitrios!  I hope when you say that you are building this tank, that you mean you are having it built.  This is not a DIY project!  I would begin by contacting some of the following:  A large public aquarium, Reynolds Polymer and San Diego Plastics.  I would consult a structural engineer about the floor.  A public aquarium should be able to direct you to large tank manufacturer (SD Plastics is one, but this project may be beyond even their capabilities).  Reynolds polymer makes very large, very thick acrylic material for public aquariums.  They can probably direct you to a manufacturer that deals in large display tanks.  There are wall thickness calculators on the 'net for acrylic tanks, but they only apply to rectangular tanks.  Good luck!  Adam>