Acrylic Tank Bowing - How much is too much??

[Jimbellottie1]

Just wanted to double check to make sure that I am not worrying about something that is considered 'normal' in some cases.

Here's the scenario:
This will be my first acrylic tank, but I am experienced in the hobby. The tank is going to be built into a wall downstairs and the stand is completed and perfectly level. The tank, based off an Aquarium Calculator is 280 gallons, and the dimensions are 96"(l) x 24"(w) x 29"(h) x 1/2".

After filling the tank with water only (no rock or substrate) to start the cleaning process, we noticed the both the front and back had started to develop a bow. Putting a large square on top of the tank and having it hang down the front, from the center of the bow to the top of the tank, it seems to be about 3/8" to a 1/2" bow. If it matters, the water is pretty cold, but not sure how much that would play a part.

Note: the tank does have an acrylic top that has 3 spots cut out for light, feeding and general maintenance. So there is definitely ample support.

Should I be concerned? Is this normal? Would like some advice from the experience acrylic tank owners...

Thanks all!

 

[Bilk]

On no. I think that tank should have been made with 3/4" acrylic. I had a 200g built and the builder insisted he use 3/4" vs 1/2". Your tank is long and deeper than mine at 24". I'm surprised the builder didn't suggest 3/4".

 

[Black Mammoth]

I agree with Bilk. My new tank will be similar in size at 96"L x 30"W x 26"T. I talked to James at Envision about the tank. He is suggesting at least 3/4" for that size and that is what he quoted me. I could even go up to 1". He also made sure it had enough cross braces. Sounds like you have enough cross braces. You may want to talk to your builder.

 

[letoan]

Mine is 72x30x30 and its 3/4". The builder refused to use anything under 3/4". Like BM said, talk to the builder. Doesn't sound very safe in a long run IMO.

 

[biecacka]

My 48/48/24 is 3/4 in thick acrylic. Agreed talk to builder, get it resolved.

Corey

 

[cabinetman123]

Ya 1/2 is way to thin. Especially for 30" tall. I wouldn't have gone any thinner than 1" personally. 3/4 at a bare minimum. I'd be on that builder like a fly on crap

 

[SPotter]

+1000 to what everyone above has said. My 96x36x24 was built by james at envision acrylics and he wouldn't build it with anything less than 3/4". Who built your tank?

 

[kmu]

Im having a 96x24x24 with 1" acrylic been built right now for my office, it will be a FOWLR...

 

[dinger28]

+1 on what everyone has said. Have my 96 x 24 x 30 acrylic 300 gallon with 3/4 thickness. Could have gone to an inch, but was happy with 3/4. Def. wouldn't trust 1/2 inch. Just my .02

 

[deansreef]

my 240 gallon cube is 3/4"

 

[guserto4]

I used to have a 115x48x15" tank and even at 15" tall it was 3/4" thick. That 8'+ length really builds the stress. 1/2" is too thin IMO.

 

[slief]

On no. I think that tank should have been made with 3/4" acrylic. I had a 200g built and the builder insisted he use 3/4" vs 1/2". Your tank is long and deeper than mine at 24". I'm surprised the builder didn't suggest 3/4".

+1. That tank should absolutely have been made with 3/4" at the very least. That 29" height just compounds things. The bowing will get worse and your acrylic WILL craze and form stress cracks. If it were my tank, I would have used 1" on the front and back which may have been overkill but better safe than sorry. More over, if I am investing that much money into a tank, I want it to last! What also concerns me is that if the builder was naive enough to build it out of 1/2" material, I'd bet he also used really poor quality acrylic. Not all acrylic is alike and quality acrylic will last a lifetime where as poor quality acrylic will show signs of fatigue fairly quickly.

My last 240 which was 96x24x24" was made from 3/4. My 480 which is 96x48x24 tall has 1.5" front, back and top with 1" sides and bottom. I had it custom made 20 years ago and there is absolutely no bowing or crazing. I cringe when I read about people building their own acrylic tanks and using material that is too thin. There was a thread recently with a home made 480g tank made of 3/4" material and all I could think of was how big a mistake that actually was yet there were people here who said it was fine and those same people had no idea what quality material he used and didn't even think to ask. Clearly misinformed IMO.

Improperly built tanks of this proportion can cause disasters of epic proportions if something fails.

 

[Mark...]

I have a 1/2" 180g 6' x 2' x 2' that is heavy eurobraced. I do see some crazing. Tank has been running for ten months. Any thoughts?

 

[Jim.mer]

Yes 1/2 inch doesn't seem right, that's a big *** tank, shouda been an inch, but it's done. So get a brace in the middle, hang it will be fine just like a big ole clamp. Good Luck

 

[Mark...]

Does this bracing make a difference. I'd hate to break down this tank...

 

[Mark...]

Here is the crazing I'm talking about..difficult to shoot with camera phone.

 

[slief]

Here is the crazing I'm talking about..difficult to shoot with camera phone.

I've seen worse crazing.. I don't think it's time to panic yet. As to your question above, bracing does help but it won't necessarily prevent bowing in the middle of the tank.

 

[Mark...]

I've seen worse crazing.. I don't think it's time to panic yet. As to your question above, bracing does help but it won't necessarily prevent bowing in the middle of the tank.

Thanks for the reply...after Pete's tank, I'm getting nervous. My front panel looks good but right side panel is off slightly after putting a square on it. Do you think I should replace the tank?

 

[slief]

Thanks for the reply...after Pete's tank, I'm getting nervous. My front panel looks good but right side panel is off slightly after putting a square on it. Do you think I should replace the tank?

Without seeing it, I wouldn't want to speculate. That said, I think the real key is the seams. If the seams aren't separating and you don't see air or water intrusion them, then you are probably OK. At least for the time being. Peters situation is probably a bit different given the size of his tank.

 

[Mark...]

Without seeing it, I wouldn't want to speculate. That said, I think the real key is the seams. If the seams aren't separating and you don't see air or water intrusion them, then you are probably OK. At least for the time being. Peters situation is probably a bit different given the size of his tank.

Seems look ok in that regard. I'm going to just keep a close eye on things and make a change if the seams change. Thanks again!