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View Full Version : Newly built stand - tank is rocking... ARGH!



Adam Cavaliere
09-16-2009, 11:40 AM
I just built a new stand. It is for a 90 gallon tank.

The frame was built out of 2x4's and framed with plywood and trim.

After I built the frame, I put the stand on it and there was no rocking - it was completely fine!

Now I have put all the plywood on, put the trim on and finished it. I moved the stand out of the garage and put the tank on it and it is ROCKING!

The stand does not rock, but the tank on the stand rocks. It isn't much at all, but I want to know how paranoid I should be. I believe the amount of travel is equivalent to about a 16th of an inch.

I filled it halfway with water last night and the rocking stopped, I then emptied the tank and it was rocking again. I can put a shim underneath the corner, but I'd like to know if that is OK to do.

Finally, there are a few spots where I can see a sliver of light between the bottom of the tank and the 2x4. Do you think that is an issue?

I would like to point out that I realize 2x4s are not perfectly flat like dimensioned lumber is. I just want to know if others who have built their stands have experienced the same and if I am just being too paranoid?!

Rod Sheridan
09-16-2009, 11:51 AM
Adam, I've made a couple of stands for friends aquariums and have made sure that the stand is absolutely flat.

Anywhere that it isn't supporting the tank, there will be bending stress applied to the glass.

Glass only bends slightly before it cracks.

I suggest you let your stand sit for a few weeks in the proper location for it, to allow the construction lumber humidity to reach equilibrium.

Then you can hand plane the tank area flat.

Regards, Rod.

Adam Cavaliere
09-16-2009, 11:58 AM
Rod,

It will be near impossible to hand plane flat as I have trim attached all the way around on three sides. The block plane will not be able to work across the whole surface because of that.

Chip Lindley
09-16-2009, 12:09 PM
Filling a void with a shim gives same results as planing the whole surface flat.

But, filling a 90 gallon tank full of water will press hard into the construction lumber beneath. I don't think you will see 1/16" of daylight then!

johnny means
09-16-2009, 12:22 PM
In the future you may want to forgo 2x4s for anything but framing up walls and try ripping low cost plywood into 4" strips. This is every bit as strong, almost as cheap, and works much better for making nice square, straight interior frames. it even makes for a hell of a stiff, light work bench with very little material.

As far as your current project could you fill the gap under the tank with some caulk? Saved my butt many a time.

Bruce Page
09-16-2009, 12:28 PM
I can put a shim underneath the corner, but I'd like to know if that is OK to do.

Finally, there are a few spots where I can see a sliver of light between the bottom of the tank and the 2x4. Do you think that is an issue?



I had a slight rocking issue with my 110 gal setup when we switched from carpeting to tile floors. I shimed it.

I wouldn't worry abought a sliver of light. The tank will safely flex a small amount if your stand top is reasonably flat.

Cody Colston
09-16-2009, 2:04 PM
Before you do anything to the stand, place the empty tank on another known flat surface and see if it rocks. The uneveness may lie with the tank and not the stand.

In any event, Idoubt if that 1/16" will matter once you fill the tank. 90 gallons of fresh water = about 750 lbs. I doubt it will rock when full. :)

Don Bullock
09-16-2009, 2:22 PM
My concern wouldn't be breaking of the tanks glass. It should be flexible enough. I had a similar situation and the silicon seam broke from the stress. It happened when my wife and I were living in a third floor apartment. :eek: As I was draining the tank using the garden hose from the apartment, after running down and up three flights os stairs, the investment group that owned the building was visiting and saw the hose draining water from my balcony. Fortunately they just smiled.:D

Josiah Bartlett
09-16-2009, 2:25 PM
Since you have trim around it, I would use a thin layer of self leveling flooring compound between the tank and the top to remove the gap. You could even paint it afterward or put some 1/4" ply over it if you are worried about visibility.

Jeff Monson
09-16-2009, 4:33 PM
Adam, I think you are going to be fine, I have a 90 gallon setup and had similar issues (my stand rocked), its been up and running for 5 years and is solid as a rock.
With over 700 lbs of pressure I'm sure the stand will conform with the tank, if you were dealing with a 1/4" I'd be more concerned but a 1/16 should not be an issue.

Ronald Mancini
09-16-2009, 4:57 PM
I line the areas where the tank is high with plaster of paris then put the tank on top. Let it dry and there will be no rocking. I have used this method with rocking toilets for decades and it solves the problem every time.

Scott Hildenbrand
09-16-2009, 5:09 PM
The stand does not rock, but the tank on the stand rocks.

[Just checking. The TANK ITSELF rocks.. NOT the stand? Bad juju..]

If it rocks, it will stress it and lead to a fracture and subsequent catastrophic destruction.. That's alot of water to be pressing down..

Didn't see how MUCH rocking it does.. You just say a little? How little is a little?

Pick up a sheet of thin blue foam insulation, the kind that's folded over? That should give enough adjustment room via compression that the stress on the tank glass will be elevated.

Might Google The Krib on the subject.. It's a method that's been used many times over and IMO is standard practice.. Know I've got a sheet under my 75 gallon tank.

Quick check shows the tank weight on average is 1050lb full, which can very depending on how much substrate and decorative rock is in it.. I've got 200lb of rock in mine.

http://www.homeaquariums.info/intro-tables.html

Lee Schierer
09-16-2009, 5:20 PM
Most likely you have one of two problems. Either the floor where you assembled it wasn't perfectly level or the floor where it is now isn't perfectly level.

Move the stand to where it is supposed to go. Check it for level on all four sides. Shim the feet as needed to get level, the weight of the tank will do the rest.

Scott Hildenbrand
09-16-2009, 5:30 PM
the weight of the tank will do the rest.

That depends on how well he built the stand.. In order for it to do the rest, it would have to force the stand to rack out of the current alignment which is causing the tank to rock. Else the force is all on the tank itself, which will not take well to being racked.

Stanley Smith
09-16-2009, 5:30 PM
Pick up a sheet of thin blue foam insulation, the kind that's folded over? That should give enough adjustment room via compression that the stress on the tank glass will be elevated.

Might Google The Krib on the subject.. It's a method that's been used many times over and IMO is standard practice.. Know I've got a sheet under my 75 gallon tank.

+1, will take care of the problem. Use it on anything over 55 gal.

Scott Hildenbrand
09-16-2009, 5:44 PM
Finally, there are a few spots where I can see a sliver of light between the bottom of the tank and the 2x4. Do you think that is an issue?

I missed this issue when I read it... Would have to see pictures to see exactly where it is you're talking about to see if it's a structural issue that would affect the tank integrity or if it's just esthetic.

Cliff Rohrabacher
09-16-2009, 5:50 PM
you can Flatten the top using a thin coat of plaster of Paris.

Trowel a thin coat on and set the tank on top. Be prepared for squeeze out. Have a level handy. the plaster will harden into a solid incompressible conformal layer making the connection between the wood and the tank a perfect fit.

This is how one should place a toilet on a tiled floor to prevent rocking later on when three hundred pounds of Aunt Sally wiggles her self down.

However, if the structure is rocking - at all - abandon it.
Drain the tank find a new home for the fish and throw the stand away.

the weight of 90 Gallons (751.5 pounds) will eventually find the weak spot and in the middle of the night ~ ~ ~ ~

Josiah Bartlett
09-16-2009, 9:06 PM
you can Flatten the top using a thin coat of plaster of Paris.

Trowel a thin coat on and set the tank on top. Be prepared for squeeze out. Have a level handy. the plaster will harden into a solid incompressible conformal layer making the connection between the wood and the tank a perfect fit.

This is how one should place a toilet on a tiled floor to prevent rocking later on when three hundred pounds of Aunt Sally wiggles her self down.

However, if the structure is rocking - at all - abandon it.
Drain the tank find a new home for the fish and throw the stand away.

the weight of 90 Gallons (751.5 pounds) will eventually find the weak spot and in the middle of the night ~ ~ ~ ~

I have a 55 gallon with a stand that I built... I wasn't expecting my floor to be even, so I built it with 6 heavy duty adjustable appliance style jack legs that go into threaded inserts. I put the stand on the floor, put the aquarium on top, adjusted the legs for level, and then filled it. It has been reliable and rock-free for 5 years.

Kelly C. Hanna
09-16-2009, 9:39 PM
I've built about 15-16 aquarium stands over the years. It's very hard to have everything perfectly flat, but the beauty is you don't have to. The weight of the tank with water evens things out. I sure wouldn't shim it, I know others have done this, but the stress on the glass WILL result in failure in the long run. My buddy shimmed his after I built it and all 350 gallons wound up on his carpeted floors....in the whole house. Bottom seal failure due to stress.

Also to think about is the tank itself...if it rocks it might not be straight and could already be stressed.

I am sure with most tanks of a smaller size this would not be as much of an issue, but with the big bys, I'd shy away from shimming.

Scott Hildenbrand
09-16-2009, 10:31 PM
Mostly everyone seems to be missing the point that it's not the stand that's rocking, but the aquarium sitting on the stand, which is a large issue.

The thin foam is a proven fix.