Acrylic Aquarium build.      1/20/19 Hi guys/Bob, <Good morn Mike> I’ve built a custom (cell cast) aquarium 60”X36”x 24.5” high top and are 1/2” acrylic, side panels are just shy of 3/4” acrylic. Joint gaps before glue are .02”. Glue used is Scigrip 42.(you can’t beat 4000psi) Some small bubble here and there and some crazing. Tank holds water fine. Long side panels bow measured from Center with a two foot level, <A note here: I'd use a longer level... > I get a 1/16” gap from left to right at either end of level. From top to bottom I get 1/8” gap at either end of my 24” level. Is this bowing ok? <Mmm; likely so; considering the thickness of acrylic used here. Are you sure the stand itself is level?> I get very little bow at the short ends of my tank. I drained half the water and found the bow very similar than when the tank is full. <Ah, yes; the material is not going to bow itself> I was planning on running an old Tunze wave box on the tank as part of a stress test to test the seams. Tank panels were laser cut and all lasered edges were shaved off till stress bowing of the panels were relieved. <Oh! Neat! Not a worry then.> One of the well known tank manufacturer wanted to make this tank out of 100% 1/2” acrylic. I totally didn’t want that!!! <Agree/d> Thanks for your help. Mike <Thank you for sharing. Bob Fenner>

Re: Acrylic Aquarium build.     1/21/19 Hi Bob, <Mike> The tank isn’t perfectly level but I did make sure there was no twist in the stand before adding water to the tank. I used a high quality level. Accurate to .0005”! <Wow> I can certainly use a longer level or straight edge for the 60” but I was using it as a brief reference. I would imagine 18” past my 2ft level at centre would be 1/8-3/16” gap at either end. I can confirm this when I do another water test. <Yes I would> I have to ask you again. How comfortable are you with the thickness of acrylic I used, high quality glue, my application method and amount of bowing? <Am very fine w/ all> Best regards Bob! Mike <Cheers, BobF>

Cracked Acrylic Tank- RMF please comment 6/9/08 I just picked up a used 500 gallon acrylic tank 8ft long 4ft deep 2ft tall. <Wow, that is a lot to pick up!> After getting it home I noticed the bottom panel has a few cracks. <Yikes!> The tank was made with 1/2in acrylic except for the bottom which for some reason I really don't understand is only 1/4in. <Cost likely, needless to say the bottom (and the sides) are not thick enough material for this size tank. You can see the results of this in what you have on your hands now. Think of the bottom having the same function as the top brace, ¼' would never be adequate for a tank this size. As for the sides, although many online resources and calculators say ½' is enough, I am not comfortable with any less than ¾' on a tank this size, even for the bottom. This tank in ½' will have a scary amount of bowing.><<RMF is in agreement... particularly re the bottom... worrisome if not totally supported flat>> With that being said is it possible to replace this with 1/2in or could I just place another panel under that one and patch the cracks on the inside also? <Considering the panel is too thin to begin with, I would simply replace it with thicker material, perhaps considering cutting the height of the tank down in the process to a more appropriate height for the material (20' or so, assuming there is sufficient cross bracing on the top).> Then there is always scraping the tank but my wife would most likely kill me. Any help would be great. <Do not scrap the tank, you have gobs of usable acrylic. If you are at all handy you can surely fabricate a more appropriate size using this material. Good luck, Scott V.> <<RMF is more inclined to go with the writer's suggestion here... and anneal/solvent another piece onto the existing too-thin bottom... IF this can be done practically... i.e., if the existing base is not too uneven/non-planar>>

Acrylic repair   3/4/06 Hello Bob, <Tony> I would like your advice on repair of acrylic tank.  I have never owned an acrylic tank before.  Just purchased an 180 gallon acrylic fish tank. The previous owner made 3 holes for pipes used in an overflow sump. ( mostly for salt water). I need to plug up the holes to house my Arowana. Any advise on how to plug up these holes.. Any suggestion would be helpful.. Thanks Tony <I would make these "temporary"... rather than affix the mentioned cover pieces with solvent (as the rest of the seams)... By using Silastic (100% Silicone Sealant) and "squares" of appropriately thick acrylic (look in the "used/scrap bin" of a plastics dealer/fabricator), over-lapping the holes by an inch or more, making a thin bead, smooshing the covers onto the inside of the tank, over the holes, taping in place for a day or so... Bob Fenner>

Re: acrylic repair   03/07/06 thank you for your help <Oh, and I do hope/sense we will "meet again" (same bat-fish channel plus), when you "uncover" these through puts to make this tank part of a reef system. Cheers, BobF>  

Jim Dorsey, California Aquatics Bob, Oddly enough, Donna from Dr. Kaplan's office [Pediatric Urological Associates] called and, as you remember, you installed a Tru-Vu 75 Hex Tank in -oh about 1982. <Yikes! Yes, a very nice fellow, and great office staff as I recall.> Well, one of the kids knocked off the canopy [again] and we are having trouble finding Aquaplex. Did Bill Montgomery finally get how of the business? <I don't think so... but... pls see below> How can we do that? <Finally get out of the business? Wish I knew!> Do you know of any other acrylic canopy manufactures? <Yes. Have San Diego Plastics fabricate a sturdier replacement> Thought you might get a kick out of this one! Check out are site @ www.californiaaquatics.com Jim <Very nice. Be chatting, Bob Fenner>

Re: tuff acrylic cleaning question, repair Thanks Bob, I ended up having to use lighter fluid to clean this stuff off, it was caked on pretty good. <As long as you're "right there" wiping off the excess (so it doesn't melt the acrylic) this works pretty well> I have another question. I found two small chips on the corner of the bottom plate, about 1/4" around and maybe 1/8" deep. The acrylic is 1 inch think at that location so I don't think it will be harmful. Do you think that I can put some acrylic glue in the chip just to give it some strength in that area. <Might help. Have you considered adding some "square doweling" in the corner. This stuff comes in stock sizes with two of the four sides "square" and the other two a bit concave. You solvent (as in with Weld-on) the two flat sides to the tank inside corners. Bob Fenner> Thanks

Repairing a hole in a sump When I recently tore down my tank I left a heater on in a small amount of water in the sump. It is acrylic, It burned a hole in the bottom and side with some bubbling of the acrylic.  I was wondering if I could cut out the affected area and glue some new plexi over the top of the cut out area.  It is a hidden sump so it doesn't matter what it looks like, just cost a lot so I would like to recover. Thanks, Mike <Actually, if the acrylic isn't too bubbled, you could just cut or have cut some small pieces of sheet (look in an acrylic outlets "bargain" box or ask for scraps, cut-offs...) and simply silicone them in place on the inside, over the holes, damaged area. Bob Fenner> Tank repair I've a problem with the plastic trim on the top of my 55 gallon fresh water aquarium.  I've looked at many questions you've listed but did not see mine, specifically. It was a saltwater tank that crashed, so I was cleaning it out thoroughly.  While turning it onto its side, I accidentally broke the cross member piece of plastic (part of the trip on the top of the tank.)  On my other 55 gallon tank, its the piece of plastic that divides the top of the tank in order to accommodate two separate lights. I put the tank back together, filled it with water and began the pumping process, etc.  There is a very large wooden light holder that fits on top (lighting for salt and a 75-watter).  When I put this top in place, I noticed that the lid would not close correctly.  I looked at the front of the tank and noticed a slight bow to the plastic strip on the front side and back side.  I'm assuming that if the strip is a bit bowed, so are the front and back sides. I noticed no leaks, but for safety and peace of mind, removed half the water and shut down the tank.  Here's my question:  given that the trim really doesn't support the tank, per se, can I fill it back up and use a clamp to pull the front and back sides toward each other?  Just enough to remove the bow and not crack the trim?  At first I used duct tape and it did the trick until the lights warmed the tape up and it began to expand.  The clamp won't be visible as the large light-holding top will disguise it.  Also, the clamp ends will attach only to the plastic trip, not the aquarium Plexiglas. <Owen, "aquarium Plexiglas".  I'm thinking this is an acrylic tank.  If so, just get a piece of acrylic, 1/4" thick, cut to the width of the tank by about two inches wide, then with acrylic cement, fasten the new cross member to the top of the tank.  James (Salty Dog)> Thanks for your help. Owen

Acrylic repair Salty Dog, Thanks for the reply and the suggestions;<You're welcome> I'll give it a shot.  Our pet shop here doesn't carry repair parts....would Lowe's or Home Depot carry acrylic? <Owen, Don't know. If they don't have it, try a glass repair shop. If they don't carry it they can probably lead you in the right direction.  Also, look in the Yellow Pages under acrylic.  Good luck.  James (Salty Dog)> Thanks Owen

Stocking 75 gallon Marine System & Covering Unwanted Holes Hi WWM Guys, <Hello Spencer> I have a 75 gal with live rock and a varied number of snails that I got for algae control as per some articles I read at WWM. My abalone and top crown snails died for some reason but the rest seem to be doing fine. I have some hair algae growing on my live rock but nobody seems to want to eat it. I'm thinking about getting a lawnmower blenny or a black Sailfin blenny to finish up the rest of the algae. Which is going to do better? <The Lawnmower> I prefer the looks of the Black. I also have read article about hermit crabs (scarlet or blue legged) and some guys think they eat algae like crazy and some thing they are a waste. What is the consensus opinion? <Don't think there is one> One last question, I have only one corner for my overflow and the last guy that owned my tank removed the quarter sized punch-outs next to the inlet slots and some of my livestock gets into my overflow then get stuck on my strainer and dies. Is their any device which stops up the semi-circles that have been removed? Thanks, Spence <I would cut or have cut a thin piece of acrylic sheet, with overflow slots... and adhere (carefully, with acrylic solvent... this in place on the face of your currently modified overflow. Bob Fenner> 

Acrylic seam is separating Nice web site! I have an 18 months old 190 gallon thriving  reef tank, 6Lx2Wx2H acrylic.  The top seam, both front and back, is separating in several areas (the side seams are fine). <Yeeikes!>   My wife and I had recently moved and the tank had to be moved and set up several times within a 5 month period.  This was probably the catalyst for my current problem.   I tried injecting weld-on #4 into the gaps with no luck.  I have read (on-line) that by trying to re-bond a seam will only weaken the existing bond.   <Possibly> Whether this is true or not is probably not important at this point, though it does mar the surface when the stuff drips down the front of your tank...very nauseating, as I now have a small bow (12 inches) in the back and a leak in the front.   I went down to my local plastics supply store and discussed the problem with them.  We decided that by bonding a 4 inch wide piece of 1/4 inch acrylic bent at 90 degrees to the front and back of the top seams would be the best solution.  Since the bent pieces of acrylic will have a small radius on the inner side, it was suggested that a product like weld-on #13 be applied to the gap caused by this radius.   <Interesting...> Hopefully you have a good mental picture of what I am describing. As I am writing this, I realized that the outer edge of my tank forms a sharp 90 degree angle and would need to be rounded off in order to accommodate the bent piece being bonded to it.  Round over sharp is not a compatible fit.  Soooo... I guess I'll start my questions off with this one:   What is the best way to "cleanly" round off the top edge since I don't own a router and would not trust myself to use one on my tank. <Borrow or buy a router> Can weld-on #13, or a similar product, be used to bond acrylic?  If not, what can I use and how can I avoid a mess?  I am afraid that #4 dripping down the front of my tank will cause me to go #2. <Mmm, I would use the "thickest" (most gel-like) acrylic weld-solvent that you can find> It seems that I also need to seal the tank seams from the inside as well.  How can I best prepare the area to be sealed and is weld-on #13 (or similar) the best product to use?  Small pieces of coralline algae and salt deposits have accumulated in these exposed areas. <Is the best, the surfaces need to be absolutely clean and dry> Are there similar products to weld-on? <Not generally available to the consumer> Finally, is there a better approach to this problem.  A new tank is not an option. <Might I ask who made this tank originally? Have you contacted them? Have you considered just cutting, attaching square (on two sides) acrylic doweling in all corner/joints? Won't take out the bowing (likely nothing will), but is the best shot at stopping this tank from coming apart)> The good news is that the area of concern is limited to the top of the tank (so far).  Our corals and fish can be no healthier, my wife is a very good marine and freshwater aquarist (sp.) and because of this, I get to believe I am as well. I would really appreciate any help or advice you can offer.  I am picking up the supplies mentioned above today but will hold off with any repairs until you respond... no pressure intended... we have clamps holding things together. Thanks, Jim <Jim, have someone or folks from the "plastics supply" come by and look at your project... they may have clamps, other ideas to help you here. Bob Fenner>