How much bowing is acceptable in an Acrylic aquarium?

J

Jukas

New member
I just noticed as I walked towards my 75g ( 4'l x 18"d x 2' H) acrylic tank that it has a visual bowing on the front panel. I'm guessing it's been doing it for quite some time. it has a top brace to the tank.

To be sure it wasn't my eyes playing tricks on my I took a 2' straight edge and confirmed it does not lay flat.

I know acrylic flexes, I'm just not sure how to determine when bowing is normal vs when it's time to be concerned.
 
A little bowing is normal, especially on many production tanks that are made with minimal acrylic thickness

As long as its braced properly you should have nothing to worry about

wouldnt hurt to post a pic and say the thickness of the tank to really be sure
 
I have seen a lot of tanks bow lengthwise, and if well braced its not a issue. The vertical bowing is a first for me- and I am not sure how the bracing would help it-other than the obvious keeping the panel in place. I hope more folks post on this with their experiences,as it seems out of the ordinary to me.
 
Bowing is very common with thin acrylic. I had my 600g made with 1 1/4" acrylic so there wouldn't be any deflection. The tank should be fine... it just looks kinda funny.
 
1/4" acrylic is pretty thin so i'm not surprised that it bows some. shouldn't be a problem with only 75 gallons. just watch for grazing in the acrylic and watch the joints just to be sure.
 
I would be extremely concerned with that amount of bowing, and 1/4" is way too thin for that dimension of tank (regardless of how much bracing it has) IMO. Not to be all doom and gloom, but it wouldn't be in my living room if it was free.
 
This is a production tank at 48 l x 18 d x 24 h. I measured the thickness top down of the front sheet of acrylic and it looks to be 3/8th. From a bit of googling that seems to be standard of sub 150g mass produced tanks.

The bowing is exactly where I would expect to see it, in the center of the longest front pane and dead center vertically. Seems logical as it's the farthest point from bracing via side and top panels.

I'm just starting the planning stages of a new tank, but I likely won't be ready to start for a least six months. So I'm trying to gauge how to tell when bowing goes from abnormal to a problem.

Im not familiar with what acrylic grazing is, what should I be looking for?
 
Jukas, don't worry about this at all IMO. My LFS has a 10 foot long 400 hundred gallon tank with a Red Tail Catfish and that sucker bows much more than that. The tank has been in the store for over 15 years with no issues. I also doubt that it's 1/4 inch acrylic. My guess is maybe 3/8 or 7/16 is what you have. The bracing is the key on acrylic tanks.
 
Jukas said:
Im not familiar with what acrylic grazing is, what should I be looking for?
Click to expand...



Its Crazing.

look along any seams/joints for tiny cracks. Just becaue you see crazing doesnt mean anything is necessarily majorly wrong. Pretty much all acrylic tanks, even ones built with more proper acrylic thickness will show crazing over time, more so if they are misused/stressed/not taken care of or cleaned with inappropriate solvents

Ive only personally seen one instance of crazing exteme enough to actually give way and it was on a 225 somebody had made out of 1/2"(which is actually kind of similar to the underbuilt you are dealing with) and it was about ten years old and had went through mulitple moves and abuse of doing very uncommon modifications to it. It didnt burst...just started to leak the tiniest of amounts and needed taken care of asap or it could have popped

I also agree with Alex. while not ideal, as long as that center brace is intact I wouldnt lose any sleep over it.

It might make a great sump for your new tank :)
 
Last edited:
RokleM said:
I would be extremely concerned with that amount of bowing, and 1/4" is way too thin for that dimension of tank (regardless of how much bracing it has) IMO. Not to be all doom and gloom, but it wouldn't be in my living room if it was free.
Click to expand...

its a production tank by idk maybe truvu? I think the tank is gonna be fine. they have been making tank for years do you really think they messed up on his? lol would you really call the company truvu and tell them they dont know how to make acrylic tanks?
 
flyyyguy said:
Its Crazing.

look along any seams/joints for tiny cracks. Just becaue you see crazing doesnt mean anything is necessarily majorly wrong. Pretty much all acrylic tanks, even ones built with more proper acrylic thickness will show crazing over time, more so if they are misused/stressed/not taken care of or cleaned with inappropriate solvents

Ive only personally seen one instance of crazing exteme enough to actually give way and it was on a 225 somebody had made out of 1/2"(which is actually kind of similar to the underbuilt you are dealing with) and it was about ten years old and had went through mulitple moves and abuse of doing very uncommon modifications to it. It didnt burst...just started to leak the tiniest of amounts and needed taken care of asap or it could have popped

I also agree with Alex. while not ideal, as long as that center brace is intact I wouldnt lose any sleep over it.

It might make a great sump for your new tank :)
Click to expand...

Thanks for the info, I've seen crazing before now that you describe it, just never knew what it was called. I checked all the seams they're all intact with no issues to be found. For now I'll just make inspecting it part of my maintenance routine and keep an eye on it for further problems.

Add this to the laundry list of reasons why my next tank will most likely be glass or at minimum custom manufactured.

flyyyguy said:
It might make a great sump for your new tank :)
Click to expand...

An interesting thought, but not likely. For economical reasons I'll be staying sub 150g on the new tank, and honestly I've hated this tank for so long that when I finally replace it I won't be keeping it.
 
My 300 bows the same way, its been up for 2 years and thank fully no leaks,looks weird from the side though! With a level from center of bow to top of my tank its a true inch. I built my base and there was a slight crown in it. It doesnt take much for acrylic to bow. I do have some crazing on upper corners. You should be fine.
 
karsseboom said:
its a production tank by idk maybe truvu? I think the tank is gonna be fine. they have been making tank for years do you really think they messed up on his? lol would you really call the company truvu and tell them they dont know how to make acrylic tanks?
Click to expand...

Nope, becuase it's not in my living room. ;) Having done acrylic work myself (rarely use anything less than 1/2 or 3/8th and that on smaller tanks), again, I personally think it's too much bowing. From the pictures it doesn't even look like the surface is flat enough to properly clean the surface with a flat device.

To each their own, just two cents.
 
Jukas said:
This is a production tank at 48 l x 18 d x 24 h. I measured the thickness top down of the front sheet of acrylic and it looks to be 3/8th. From a bit of googling that seems to be standard of sub 150g mass produced tanks.

The bowing is exactly where I would expect to see it, in the center of the longest front pane and dead center vertically. Seems logical as it's the farthest point from bracing via side and top panels.

I'm just starting the planning stages of a new tank, but I likely won't be ready to start for a least six months. So I'm trying to gauge how to tell when bowing goes from abnormal to a problem.

Im not familiar with what acrylic grazing is, what should I be looking for?
Click to expand...


No, it's actually a bit below vertically center.
Highest pressure is at bottom tank.
Softest tank spot is smack in the middle.
Whereas top bowing is in a point in between this two, a bit below the vertical center.

For the bowing... Omg haven't seen anything like this... Ever.
Wouldn't put this inside my house nor would I put anything alive in there, it may be strong enough, but I would be afraid to breathe in the same room.
 
I've never owned an acrylic tank or have any knowledge of how an acrylic tank should flex but i can tell you that i would be sick at my stomach when I first found that and if it was my tank would be looking to go a different path. Like i said I am VERY uninformed on the subject but that's just my take on it!
 
flyyyguy said:
Its Crazing.

look along any seams/joints for tiny cracks. Just becaue you see crazing doesnt mean anything is necessarily majorly wrong. Pretty much all acrylic tanks, even ones built with more proper acrylic thickness will show crazing over time, more so if they are misused/stressed/not taken care of or cleaned with inappropriate solvents

Ive only personally seen one instance of crazing exteme enough to actually give way and it was on a 225 somebody had made out of 1/2"(which is actually kind of similar to the underbuilt you are dealing with) and it was about ten years old and had went through mulitple moves and abuse of doing very uncommon modifications to it. It didnt burst...just started to leak the tiniest of amounts and needed taken care of asap or it could have popped

I also agree with Alex. while not ideal, as long as that center brace is intact I wouldnt lose any sleep over it.

It might make a great sump for your new tank :)
Click to expand...

usually crazing happens on older tanks.. I have an old 15g Im using as a frag tank right now and the bottom corners are all crazed but it holds water so Im not worried about it..
 
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