Problem with a tank stand

[Jarred1]

I built a custom stand for my 40 gallon breeder and I think I have a problem. The top of the stand is 3/4" plywood with Formica on top of it. When I put the tank on the stand last night I noticed that where the plywood is screwed into the middle support 2x4 I caused it to sink the middle portion of the plywood about 1/8" to 1/4", probably closer to 1/8". My question is what can I put under the tank so it doesn't crack? I can't put a new piece of plywood on because all my finish work is done on the stand. Would a cork mat or styrofoam fix this problem?

Thanks in advance,
Jarred


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[hebygb]

Just to confirm... when you say the middle, do you mean that there is an 1/8" gap where the rim of the tank sits? Probably the long side? Is this a glass tank?

Opinions vary on this subject but... no matter what material, foam, rubber, pink, white, thick or thin, the stress caused by the gap is the same as if nothing were underneath. IMHO - The only real solution that can give you the most peace of mind is to replace the top.

 

[Jarred1]

I see what you are saying


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[Jarred1]

Just to confirm... when you say the middle, do you mean that there is an 1/8" gap where the rim of the tank sits? Probably the long side? Is this a glass tank?

Opinions vary on this subject but... no matter what material, foam, rubber, pink, white, thick or thin, the stress caused by the gap is the same as if nothing were underneath. IMHO - The only real solution that can give you the most peace of mind is to replace the top.

Yes all you assumptions are correct.


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[uncleof6]

First, never put foam, or any other filler underneath a rimmed glass tank. This will pretty much assure the destruction of the bottom panel of the tank, whether the stand top is perfect or not.

What is of concern with a glass rimmed tank, is that the four corners of the tank be directly vertically supported, and that the four corners are co-planer. Generally, a gap at the center of a side of the tank, is not much of an issue, for a rimmed tank, but could be indicative of other issues with the stand.

Since the gap, most likely is due to the framework under the top, rather than the top itself, replacing the top is not going to solve the problem. Ideally, the entire rim should sit flush on the stand, but with dimensioned lumber for the framework, most of the time, it takes a jointer to get of the crook.

 

[fishgate]

You could probably fix the bow by adding a center support directly under the middle of the long tank side (both sides front and back).

 

[der_wille_zur_macht]

Can you post a photo or drawing of the stand's construction? It's hard to give structural advice about an existing stand without knowing a lot of little details, and it would be easier to just look at a photo than to ask a bunch of questions.

 

[hebygb]

uncleof6 - you are correct, perhaps I glossed over the fact that just replacing the top is not the only path to a fix... but that obviously something wasnt correct underneath that likely caused the screwing of the top into the stand to "draw" the top out of plane (probably a lowpoint, a sagging frame piece, or an out of plane crossbrace. My point was that the top needs to come off and that foam/rubber/cork would not solve this issue.

dwzm - nothing beats a photo or 4.

 

[Jarred1]

Here is a picture of the stand with out the top (there is a 2x4 in the middle of the stand as a cross brace):

The top is two pieces of 3/4" plywood and both pieces have a slight bow upwards, which gives a small valley where the two pieces of plywood meet. I'll take a picture of it as soon as I get home and post it here.

Here is a picture of the stand finished but not stained yet:

 

[uncleof6]

uncleof6 - you are correct, perhaps I glossed over the fact that just replacing the top is not the only path to a fix... but that obviously something wasnt correct underneath that likely caused the screwing of the top into the stand to "draw" the top out of plane (probably a lowpoint, a sagging frame piece, or an out of plane crossbrace. My point was that the top needs to come off and that foam/rubber/cork would not solve this issue.

dwzm - nothing beats a photo or 4.

Certainly. But would sorta hate it if he ran out and replaced the top today, and posted tomorrow "It did not fix it " tomorrow.

 

[der_wille_zur_macht]

A 40g tank will not be able to cause a 1/8" deflection in a stand that overbuilt. I would guess the stand itself is probably not true - if I were in your shoes, I would take the top 3/4" plywood off, true up the structure, and reattach the top.

 

[Jarred1]

First, never put foam, or any other filler underneath a rimmed glass tank. This will pretty much assure the destruction of the bottom panel of the tank, whether the stand top is perfect or not.

What is of concern with a glass rimmed tank, is that the four corners of the tank be directly vertically supported, and that the four corners are co-planer. Generally, a gap at the center of a side of the tank, is not much of an issue, for a rimmed tank, but could be indicative of other issues with the stand.

Since the gap, most likely is due to the framework under the top, rather than the top itself, replacing the top is not going to solve the problem. Ideally, the entire rim should sit flush on the stand, but with dimensioned lumber for the framework, most of the time, it takes a jointer to get of the crook.

So from what you said the tank should be fine as long as the four corners are being supported and are level right? The tank has no rock to it at all I was just concerned about the center of the tank not being supported by the stand.

Jarred

 

[hebygb]

Jarred1 - I see a several issues with the composition of the stand in terms of best practices, not the least of which is the bow in the two top pieces. I will yield to uncleof6 and Der Wille, to share their specific insights.

 

[Jarred1]

Jarred1 - I see a several issues with the composition of the stand in terms of best practices, not the least of which is the bow in the two top pieces. I will yield to uncleof6 and Der Wille, to share their specific insights.

Can you please tell me what you see wrong with the stand?

 

[der_wille_zur_macht]

It looks somewhat like a typical "rocketengineer" 2x lumber stand to me. The top frame is correctly resting on top of the posts and there are nailers to keep it from racking. The plywood skin is icing on the cake, if thick enough it would likely be strong enough on it's own.

There are definitely some "weird" pieces in there but generally it looks like an intact structure.

 

[der_wille_zur_macht]

It looks somewhat like a typical "rocketengineer" 2x lumber stand to me. The top frame is correctly resting on top of the posts and there are nailers to keep it from racking. The plywood skin is icing on the cake, if thick enough it would likely be strong enough on it's own.

There are definitely some "weird" pieces in there but generally it looks like an intact structure.

 

[Jarred1]

It looks somewhat like a typical "rocketengineer" 2x lumber stand to me. The top frame is correctly resting on top of the posts and there are nailers to keep it from racking. The plywood skin is icing on the cake, if thick enough it would likely be strong enough on it's own.

There are definitely some "weird" pieces in there but generally it looks like an intact structure.

Which pieces look "weird" to you? There are no pieces of wood in the stand that don't need to be there, they all serve a purpose.

 

[uncleof6]

So from what you said the tank should be fine as long as the four corners are being supported and are level right? The tank has no rock to it at all I was just concerned about the center of the tank not being supported by the stand.

Jarred

Information from the tank manufacturers says--support at the four corners. The bottom glass panel, being NOT tempered, is thicker than the sides, and is only supported by a thin ledge on the inside of the rim. Best practice, is to disassemble, and use a jointer to get rid of the cook in the top rim, so the tank sits flush. This eliminates the possibility of issues.

In all reality, you could eliminate the lumber, and use just 3/4" hardwood plywood for the stand, and wind up in the same place you are now--without having to deal with the warp (crook) along the top and bottom edge of the lumber, as well as makes some more room inside the stand. The amount of wood you have in the stand is not needed, or in a lot of cases not even desired (due to the warp involved with dimensioned lumber)

 

[der_wille_zur_macht]

Which pieces look "weird" to you? There are no pieces of wood in the stand that don't need to be there, they all serve a purpose.

I'm sure the design serves a purpose, my "weird" comment was to indicate pieces that are not typical in 2x stands discussed on this forum, as a way of explaining why heybgb might have thought the design looked different. I've put a red line on the pieces in question:

At any rate I would definitely consider this a minor footnote, I don't see these pieces as problematic or related to the question you originally asked in any way.

 

[Jarred1]

I'm sure the design serves a purpose, my "weird" comment was to indicate pieces that are not typical in 2x stands discussed on this forum, as a way of explaining why heybgb might have thought the design looked different. I've put a red line on the pieces in question:

At any rate I would definitely consider this a minor footnote, I don't see these pieces as problematic or related to the question you originally asked in any way.

The two in the front are used to screw the plywood into because with out it the screws wouldn't attach to anything (do you get what I am saying?). The middle beam is used to attach the two different pieces of plywood that I used for the top, which is where I am having problems from because the way the pieces bow. The 2x4's in the very middle of the stand are used as supports for the shelf in the the stand.

Here is a picture of the shelf and you can also see that the top is two pieces: