Acrylic Tank Crack Repair/Drilling Acrylic – 12/30/07
Hello,
<<Greetings>>
I am writing to ask a question regarding repair to the top panel of my 110 gallon acrylic tank.
<<Okay>>
I just got the tank really cheap and it is not filled yet. The tank is 60lx24hx18w and is made of 3/8” acrylic.
<<Mmm…too thin for this “height”…you will have some bowing>>
There are 2 access holes in the top, and there is a crack running from the right side of the hole on the left to the back side of the tank.
<<Not good, as you are/should be aware…most acrylic tanks gain much of their structural integrity from the perimeter brace around the top>>
My idea is using JB Weld on the crack, then covering it with 1/8” or ¼” acrylic I have cut to size, and gluing that to the top to completely cover the crack on both sides so it won't separate again. Please let me know if this is a good approach to this problem.
<<A good plan… And although pulling the crack together and “fusing” with the solvent would likely be enough (the cracked piece would again become “one” if done correctly)…I would suggest an oversize piece of 1/8” acrylic on both sides to “sandwich” the crack for that extra measure of reassurance>>
Also, the tank has a built in overflow which is cool, I plan to keep the skimmer and heater in the sump so they aren't in the display tank.
<<Sounds good>>
My problem with this is there is no access hole near the sides for wave-makers I have and would like to put at each end of the tank. I know acrylic can be drilled easily, but drilling how close to the ends is safe, and how big a hole should I drill for the cords?
<<You mean the perimeter brace at the ends of the tank, yes? I would keep at least an inch from the tank sides…and make the hole just large enough to pass the equipment “plug-in” through. Do use a “bi-metal” hole-saw…and practice on a piece of scrap to get a “feel for it”…>>
I am paranoid about weakening the top support for this tank after hearing the horror stories about how badly a tank this height made out of this thickness acrylic will bow when filled.
<<3/8” acrylic on a 24” high tank is going to bow…period>>
Thanks for your time,
Chris
<<Happy to assist. EricR>>

Enlarging the access holes on the top of an acrylic tank
Greetings!
I started out with a 29 gallon reef, got a 65 when I found out the hard and soft corals don't get along, then got another 29 to keep the anemones and clownfish in, and my "quarantine" tank is now holding the huge evil red hermit crab I inherited that will eat anything ...this reef addiction gets out of hand quick, doesn't it?!! I no longer have the incompatible soft corals, want a bigger tank for more hard corals and flasher wrasses (the little sh**s can jump through the holes in eggcrate, will use an even tinier mesh screen), and need to get things consolidated for tank stability. I have only one non-knowledgeable fish-sitter available if I have to go anywhere, and the little tanks are too prone to fast crashes if the power goes out and the GFCI trips when everything tries to come on at once, or to temperature or salinity fluctuations, or if anything dies....
Still no reef in the backyard (whaaa!), but came up with the next best thing (at least my checkbook thought so)--I got a great deal on a used complete saltwater setup, including a 180 gallon (Clear-vu?) acrylic tank (would have preferred glass for ease of cleaning, but oh well) 6' x 2' x 2' made of 5/8" acrylic. There are two top access holes on it, but I'm short and they are so small and far in that I can hardly get my arms and hands in towards the bottom of the tank. When it's set up with a deep sandbed this will help reduce the depth, but even so, if I can't reach all the tank sides I'm rapidly going to have only scraped view holes of my reef through the pink coralline algae! and even worse--if I can't reach in to all parts of the tank I may have to disassemble the rockwork every time I need to get a dislodged coral frag or (please no) something that died out of the rockwork that I can't reach with tongs--not a pleasant thought.
I was considering cutting the holes in the top larger, so that they were at most 3" to 3.5" away from the edge of the tank (on front and sides--along the back are narrow openings for external filters that are already on the edge, so I don't know if I can go in any further), instead of the 6+ inches they are now. How close to the edge can I go without compromising the structural support of the top? (do you need a drawing or detailed measurements?) How wide does the middle bar need to be? (currently about 16") or ideally, is there some way to build a reinforcing braced edge along the top so that I can cut out most/all of the top? out of what materials?
Would I be better off building a glass tank like I was going to do in the first place? (between the chiller, MH lights, two big Iwaki pumps, 500 lbs of "live" (more like base) rock, and a full 50 gallon setup "thrown in" I'll get my money's worth even if I do have to scrap the tank)
Thanks for your time! My corals and fishes are looking greedily at the Big Tank, and at me as if to say "well, why aren't we in it yet?"
      --Kari Yanskey
(and if Anthony is answering this, at least this time it's NOT the "Preamble to the Constitution", but you'll probably dub me the "queen of parenthesis" or something. Keeheeheeheehee!)
< I wouldn’t mess with it here, you will likely just end up with bigger problems.  Also since you are using metal halides you will want as much support as you can get because of the heat.  You should be able to reach most of the algae you need to get at with a long handled scraper such as the one made by Kent. Best regards, Cody.>

Re: want to cut out top of acrylic tank part 2
Ohh, sick sinking feeling--did I say the acrylic was 5/8" thick? in the message I just sent you?  it's 3/8" thick--makes a real difference.... thanks!           --Kari
<That's better! Cody>