Tank Question tank bowing slightly

[Horsesarefun]

Slightly bowing tank.
I have decided to add a brace on this big tank. It's off by a 1/4 inch in center. Didn't notice until I tried to get a top for it. This is a old tank,,, maybe twenty plus years and I rebuilt. It's been up and going for a year now and no issues. Except it's bowing slightly. It's six foot, 24 high and 19 wide. I am a older person and I have no help anymore to move this or even pull the top off and replace. It never had a center brace and is 1/2 inch thick glass. I was thinking on making a wood brace for the top. Such as a 19 inch wide 2 x 4 to create a brace I can slide over the top and almost like a clamp. Then attach a plexi glass on the bottom side to form a edge for a lid. I'm working it out in my head right now. I am going to empty the tank about half way to 3/4 way and see if the bow is still there and it's the tank build rather than bowing. If it's bowing then I'll work out a brace for it. Thoughts?

 

[TNG]

A glass aquarium with the dimensions you describe, without a centre brace, and is made of ½ inch thick glass should not theoretically bow more than 0.5mm or 1/50th of an inch. Age of an aquarium doesn't affect how much the front or side glass bows.

I’d check it again to be sure as I can’t think of a reason why it should bow by ¼ inch.

You can check your tank using the attached link. There are several available, all should give you pretty much the same answer.

https://www.omnicalculator.com/other/aquarium-glass-thickness

 

[Magnum Man]

I have a 20 plus year old 55 gallon, of standard dimensions, mine had a plastic molded top and bottom, which incorporated a plastic brace across the middle… at some point, that plastic brace broke on one side, and I noticed there is a little over 1/4 inch gap… I typically leave this tank about an inch from full, to reduce the stress, and thought about getting some 1/4 inch stainless threaded rod, and a couple “clips” to go over the sides, just at the top, then I could adjust the pressure on the tank, to bring it back… but I’ve been running it 2 years since I noticed the plastic brace broken, with no problems, being as yours is thicker glass, I’m guessing it’s not tempered, but I think that makes a difference, as well… mine being thinner glass, I assume it’s tempered

 

[Archerfish]

I'm having difficulty with your ruler. Is one measurement taken at the top of the tank at the mid-point and the other at the top on one side? I doubt a 2x4 as pictured will do the job. It will flex. A stainless brace as Magnum Man described above is better. I wonder if the source of your problem is the tanks foundation? From looking at the image, it appears the stand is not level in the middle. Can you run a piece of paper (3x5 card) under the tank in the middle? If so, that could be the real source of your problem.

 

[Horsesarefun]

The tank is on 2 inch thick boards on top of Mason bricks on a cement floor. There isn't any gaps under it at all. It's a very solid foundation.

 

[Horsesarefun]

I have a 20 plus year old 55 gallon, of standard dimensions, mine had a plastic molded top and bottom, which incorporated a plastic brace across the middle… at some point, that plastic brace broke on one side, and I noticed there is a little over 1/4 inch gap… I typically leave this tank about an inch from full, to reduce the stress, and thought about getting some 1/4 inch stainless threaded rod, and a couple “clips” to go over the sides, just at the top, then I could adjust the pressure on the tank, to bring it back… but I’ve been running it 2 years since I noticed the plastic brace broken, with no problems, being as yours is thicker glass, I’m guessing it’s not tempered, but I think that makes a difference, as well… mine being thinner glass, I assume it’s tempered

Could you explain a little more about the threaded rod technique? Not sure i know what u mean by clips.

 

[Magnum Man]

Mine is built in, so I wouldn’t want anything hanging down, past the plastic frame (?which is roughly how much is covered by the pine car siding that the finished side of my wall is made from, so my “clips” were going to be 3/16 inch inch thick stainless flat stock, that was 1 inch wide, and 2 inches long, I am going to use 1/4 inch threaded rod, so the clips are similar, but the one on the front, would have a 1/4 inch threaded hole, so the rod would screw just slightly further than the hole in the clip, so it doesn’t interfere with the wall… the one in the back, has no interference, so a 1/4 inch hole, that the rod would slip through, with a nut on the outside… the rod would rest on the plastic frame, on top, so the holes would be at the 1/3 - 2/3 and center of the clip, and tightening the nut will put pressure on the bowed center… my tank has the plastic top frame, if yours is not framed, you will want something between the metal and glass, a nylon washer, or piece of rubber, etc. you will want the holes as close to the diameter of the rod as possible, and may need to go like twice as thick, on the slip hole, so the clip doesn’t lean too much as it’s being snugged up… if your tank doesn’t have any interference, as big as it is, I would probably use thicker rod, and clip material… but I also agree, that the lumber aren’t the material to use…

Sorry, for all the additional jiberish… I’m on my phone, and please don’t tell it so, but my AI is stupid, so between my fat fingering, and stupid AI, they can be hard to read initially… I usually try to check them later…

 

[MaloK]

The middle of the tank is sagging a little.

The longer the tank is, the more the center needs to be higher (Like a bridge) than the ends. To the point that the end have the least weight compared to the center at installation and the tank can be rocked on it. When filled the water should exerts force pushing toward both sides of the tank. Stretching the front and back glass instead of having the water having the weigh pressing the front and back glasses. It's less risky to have a tank that want to spread than collapse.

If you can lower the water level enough to be able to shim the center of the tank a little ( back and front ) with something tough, thin and wide enough to use the third of the tank positioned in the center, it doesn't need to be very thick, I used cheap schools rulers and thin formica laminates pieces.

If your tank is sagging, once a good part of the water removed, measure if the bowing is lower. if its the case shimming the center will be easy, you should be able to slip something in. It will stop the bowing.

Sometime it need more than a water change to get it. But once balanced. You don't need any center brace.

 

[Magnum Man]

I use composite shims used to install doors and windows… wood shims work equally well, as long as they never get wet

30 year old wood shims, also on dimensional lumber, and concrete blocks the shim pictures are taken from the back, the front of the tank has been trimmed out…

 

[MaloK]

Look a little rough on a show tank. But that's the spirit.

 

[Magnum Man]

The exposed shims are only visible from my work area behind the tanks… 3rd picture shows more finish

 

[MaloK]

The exposed shims are only visible from my work area behind the tanks… 3rd picture shows more finish

Just pulling your leg.

 

[Horsesarefun]

I appreciate all the advice. I think I will try the rebar on the top. I am in my fifties and have severe health problems that have hit me these last few months and doing a full tear down on a aquarium this size is not at all possible. I have no one to help me with this tank anymore or the funds right now to hire someone to do it. Maybe after tax returns but not right now.