Should Acrylic Aquariums Bow?

[oneilwiz]

Hello my fellow reefers,

I have a 20 Gallon Frag tank that is acrylic, age of the tank is around 3 years. I noticed that the front pane now bows in the middle. To what extent is it acceptable for a acrylic tank to bow or once it starts to bow it should be replaced. No leaking

.

 

[Gumbies R Us]

Hello my fellow reefers,

I have a 20 Gallon Frag tank that is acrylic, age of the tank is around 3 years. I noticed that the front pane now bows in the middle. To what extent is it acceptable for a acrylic tank to bow or once it starts to bow it should be replaced. No leaking

.

Bumping this, I'm curious about this as well

 

[Troylee]

Acrylic absorbs around 3% water… as you’ve just witnessed upon filling everything is fine and a couple days later you get that bow.. it doesn’t look terrible but it will in deed stress the glue joint over time and cause crazing “small cracks” and or hazy joints where it’s getting weak.. what are the dimensions of that tank? Length, width and height?

 

[D3DPrintedThingz]

That looks sketchy as all get out . Holy cowS

 

[JC1977]

It looks like there’s no bracing on the top?? Like a rimless tank?

 

[Lowell Lemon]

Acrylic absorbs around 3% water… as you’ve just witnessed upon filling everything is fine and a couple days later you get that bow.. it doesn’t look terrible but it will in deed stress the glue joint over time and cause crazing “small cracks” and or hazy joints where it’s getting weak.. what are the dimensions of that tank? Length, width and height?

This is the reason for a solid top with routed out access openings and a center brace. Water absorption leads to this condition. It requires extra thick panels to prevent bowing. Glass does not absorb the same level of water but can still bow without causing a problem. It is interesting how many rimless tank failures we have now days. Is this a trend we should all think twice about? Also the reduction in availability of proper cell cast acrylic may be contributing to this as well. Plexiglass G materials are no longer available as the plant was closed down. I am left with Chemcast, imports and Polycast at higher prices. Acrylite GP is no longer produced in the continent and has to be shipped from Germany with 1"to 4" the only materials produced by them. The thinner Guage of Acrylite come from China or Asia now and the materials are not the same quality.

 

[Troylee]

This is the reason for a solid top with routed out access openings and a center brace. Water absorption leads to this condition. It requires extra thick panels to prevent bowing. Glass does not absorb the same level of water but can still bow without causing a problem. It is interesting how many rimless tank failures we have now days. Is this a trend we should all think twice about? Also the reduction in availability of proper cell cast acrylic may be contributing to this as well. Plexiglass G materials are no longer available as the plant was closed down. I am left with Chemcast, imports and Polycast at higher prices. Acrylite GP is no longer produced in the continent and has to be shipped from Germany with 1"to 4" the only materials produced by them. The thinner Guage of Acrylite come from China or Asia now and the materials are not the same quality.

Materials have changed over the years just like the solvents… I’d blame the fabricator more than the material in most cases of rimless tanks giving out… I’ve got some over 20 years old still going strong..

 

[mnl119]

Hello my fellow reefers,

I have a 20 Gallon Frag tank that is acrylic, age of the tank is around 3 years. I noticed that the front pane now bows in the middle. To what extent is it acceptable for a acrylic tank to bow or once it starts to bow it should be replaced. No leaking

.

Even a brand new acrylic aquarium using standard thicknesses (e.g., 3/8" for 24" height aquarium) will bow when filled. You can tell by looking at reflections on the surface of the material... obvious distortions. Many choose to order with thicker acrylic to help minimize this.

I have never seen a rimless acrylic before. They almost always come with a solid top that has cutouts for the various access points (e.g. overflow box). The only exception that I've seen are frag tanks that are very shallow. What you have pictured seems destined for failure at some point.

 

[JC1977]

Here’s a couple pics of my acrylic tank for reference. Bracing across entire top of tank.

 

[Troylee]

Here’s a couple pics of my acrylic tank for reference. Bracing across entire top of tank.

Large tanks it’s the way to go! It’s actually more cost effective! To do a rimless that size we’re talking 2” acrylic that cost and weighs a ton lol… little frag tanks are fine rimless if built with the correct materials…

 

[oneilwiz]

Thank you all for replying this frag tank is 20 gallons, 30x 20x12. I am certainly going to pull it down this weekend

 

[nuxx Verified Sponsor]

No if the acrylic is sized correctly...

Had 1" acrylic on mine, 0 bow...

 

[Troylee]

Thank you all for replying this frag tank is 20 gallons, 30x 20x12. I am certainly going to pull it down this weekend

How thick is it? Looks 3/8” but could be half.. needs to be 3/4” or 1” at that height .. if the glue joints still look really clear I wouldn’t sweat it to much.. if it’s been used for 3 years it’s proven it will hold water..

 

[Matt1997]

I made a 36x12x12 rimless tank with offcuts from a larger build. 3/4” material and it still bows along the length. Rimless and acrylic just don’t go well with each other.

I personally do not lose sleep over my tank giving away though as I once had a 500 gallon tank 96x24x48” tall made with 1.5” material that bowed about 2” from middle to top and middle to bottom. It was fully braced. It ran for 8 years with crystal clear seams until the day I sold it.

 

[oneilwiz]

the tank is

• 1/2" Thick Rimless

 

[Troylee]

the tank is

• 1/2" Thick Rimless

I wouldn’t panic about it.. just look at the glue joints and if they’re still crystal clear it’s fine for a long time.. just gonna have that unsightly bow unfortunately.. you could always put a small frame around the the top out 1” aluminum angle or something to help you sleep at night.. if it’s 3 years old and the glue joints are clear I’d roll with it personally..

 

[oneilwiz]

I wouldn’t panic about it.. just look at the glue joints and if they’re still crystal clear it’s fine for a long time.. just gonna have that unsightly bow unfortunately.. you could always put a small frame around the the top out 1” aluminum angle or something to help you sleep at night.. if it’s 3 years old and the glue joints are clear I’d roll with it personally..

Thank you, I looked at all four joints, they are clear and seems normal. Thank you all for your input/advice. it has been over week since I reached out the manufacturer to ask the same posed question but no response.

 

[Troylee]

Thank you, I looked at all four joints, they are clear and seems normal. Thank you all for your input/advice. it has been over week since I reached out the manufacturer to ask the same posed question but no response.

If you know anyone that welds aluminum or does acrylic you could have them make you a little frame that drops over the tank and acts as a euro brace.. even a clear acrylic one out of 3/8” acrylic like 2x2 sitting over it would cure the bow.. would look and act as a euro brace and still look clean..

 

[oneilwiz]

Thank you for that tip, I wish I knew of one in Maryland /DC

 

[SteveMM62Reef]

I have 24” x 2” x 1/2” Acrylic Bridges, they are about a year old. No water pushing against them, just the Minor Weight of the glass top edges. They have slightly bowed, that’s why I made a spare, so I could weight and bend them back. So I wouldn’t worry about that minor bowing. BTW, I saw something on my Glass bottom edges of my Aquarium, that I was concerned about the glass chipping. I was able, with all the lights out to sight down the glass from the end, and determine, there was no problem. So you maybe able to sight down on the Acrylic too.