uneven surface

[ukspice69]

I have built a stand for 180 it and there is a very slight gap running less then 1/16 of an inch only 1 ft from the front right side to the left, it start about 4 inchs from edge of the aquarium, it an aga aquarium , should i put foam on the frame of the stand then put 1/2 ply on top .


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[BeanAnimal]

1/2" ply alone should do the trick. You can lightly shim it where needed to make the surface perfect. Foam UNDER the play will make matter MUCH worse. Foam under the tank is also not going to help (and AGA does not recomend it).

1/16" is not too bad, what is MUCH more important is that there are no short high spots and that all 4 corners are on the same plane. A short hump or raised corner will put much more stress on the tank than a short mid section that has no support. Not as bad, but still critical is a LOW (unsuported) corner.

 

[Rhodophyta]

Plane or sand down the high spots and it will be fine. Don't sandwich foam between wood parts. Some others have done that and they are making themselves bad examples for others to mistakenly follow. Foam compresses, so sandwiching it will weaken the structure and cause unpredictable changes in the shape of the stand. Foam goes under the tank frame where it can be changed each time the tank is moved .

 

[calkulon]

An easy way to get a dead flat surface is to use Bondo auto body filler. Mix enough to fill the low area slightly high, then lay saran wrap over the Bondo, then set the tank into place. The Bondo will set quickly, fifteen to thirty minutes. Remove the tank and you will see a dead perfect fill in. Shave and sand off the excess Bondo. The epoxy putty used for rocks and frags will work but is harder to sand and smooth.
The foam and plywood will work fine, but is a lot of wasted material as most all glass tanks are only supported on the edge of the frame.

 

[Rhodophyta]

calkulon is right that you only need the foam under the outer edges of the tank. I usually only place it on the corners, even on 6' long tanks. But the plywood top does more than support the tank, It also ties the stand frame together and helps keep it from twisting. In fact the way I insert the plywood, the tank actually rests on the 2 by 4 rails and the plywood is inset flush with the top edges of the rails.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12796785#post12796785 target=_blank>Originally posted</a> by calkulon
The foam and plywood will work fine, but is a lot of wasted material as most all glass tanks are only supported on the edge of the frame.

Foam between the plywood and frame will make matters worse.

The tank is only supported by the perimeter, but the plywood top is certainly not a waste. It will help to tie the frame together and prevent twisting or wracking. Because it is somewhat rigid, it will also tend to even out minor surface undulation and at the same time provide rigid support for the tank by transfering some of that load over the gaps.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12798810#post12798810 target=_blank>Originally posted</a> by Rhodophyta
I usually only place it on the corners,

That is certainly not a good idea. Why would you let the corners rest on something soft? Even it if compressed to 1/16" thick, you would then be asking the 6' span to conform to that new shape.

 

[jthao]

just throw the plywood on top and you should be fine.

 

[Rhodophyta]

<a href=showthread.php?s=&postid=12800185#post12800185 target=_blank>Originally posted</a> by BeanAnimal
That is certainly not a good idea. Why would you let the corners rest on something soft? Even it if compressed to 1/16" thick, you would then be asking the 6' span to conform to that new shape.

Why? Just following the manufacturers' directions. I've set up over a hundred tanks this way, from 10 gallon tanks to 240 gallons.

If this were decades back into the last century, you would have a good point. The old style tank construction with the bottom first and the walls built up on it might ping a bottom if supported on the corners, but chances are any such tank is 25 years old and maybe tacking in toward 50 years old. When those tanks were still common as used purchases back in the 70's, I would sand a plywood top perfectly flat and glue pool table felt onto it.

The reasoning for supporting just the corners with something soft is that the walls of the tank, and not the bottom, and not any part of the stand other than the corners carries the weight of the tank. If you remove the bottom plastic frame, you will see that the edges of the glass are not perfectly flat, and is probably "seamed" rather than ground so it is wavy and out of square. If you put the "modern" tank on my old pool table flat surface, the downward waves in the glass would be under stress. To quote you, certainly not a good idea.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12800561#post12800561 target=_blank>Originally posted</a> by Rhodophyta
Why? Just following the manufacturers' directions.

Sorry my friend but that is just not the case. I have NEVER seen a manufacturer recommend putting foam under the only the CORNERS of a glass tank. It makes utterly no sense and is dangerous.

Very FEW manufacturers recommend the use of FOAM under a glass tank, most insist that it must sit directly on the stand.

If this were decades back into the last century, you would have a good point. The old style tank construction with the bottom first and the walls built up on it might ping a bottom if supported on the corners, but chances are any such tank is 25 years old and maybe tacking in toward 50 years old.

You have it backwards. Most of the older tanks had the bottom panel suspended between the walls (except for some of the metal trimmed tanks).

With some (most) of the newer glass tanks, the walls are built ON the bottom panel.

The reasoning for supporting just the corners with something soft is that the walls of the tank, and not the bottom, and not any part of the stand other than the corners carries the weight of the tank.

That is not even remotely true. Even if it WAS, using a SOFT material at those support points would not be logical at all.

If you remove the bottom plastic frame, you will see that the edges of the glass are not perfectly flat, and is probably "seamed" rather than ground so it is wavy and out of square.

It is fitted to the trim with a bead of silicone along the entire perimeter. The LOAD is distributed along the entire perimeter through the vertical wall panels, and from the bottom to the perimeter.

If you put the "modern" tank on my old pool table flat surface, the downward waves in the glass would be under stress. To quote you, certainly not a good idea.

I am not even sure how to respond to that statement. You are now saying that placing the "modern" tank on a perfectly flat surface with NO foam is a bad thing? Nothing could be further from the truth.

I know your intentions are good, but your understanding of the physics at play is severally lacking. This is basic physics here. It is not even up for argument. I hate to call you out in public like that but your post is riddled with errors in logic and understanding.

 

[BeanAnimal]

So that there is no confusion...

We are talking about GLASS with bottom TRIM

Glass tanks with NO trim and/or acrlic tanks are a different ball of wax.

 

[Rhodophyta]

<a href=showthread.php?s=&postid=12801974#post12801974 target=_blank>Originally posted</a> by BeanAnimal
So that there is no confusion...

We are talking about GLASS with bottom TRIM

Glass tanks with NO trim and/or acrlic tanks are a different ball of wax.

Congratulations, Bean Animal, you have One Thing right! Acrylic tanks do need support under their entire bottom, except for near any bottom opening or fittings. Plywood tanks also need support from a solid base or close to it, especially near the glass window(s). Any kind of tank benefits from the added stability and rigidity of a solid plywood shelf on a wood stand, either flush with the rails or right on top. And a solid shelf makes it possible to temporarily use a 55 on a stand for a 75, or a flock of small tanks on that same stand.

I have a couple fish hobby friends who worked for one of the first all glass aquarium manufacturers in the early 60's, and I learned enough from them to build and repair tanks starting in the late 60's. If a tank has a plastic frame, there can always be a surprise hidden inside it, in terms of the tank construction and quality control of the glass dimensions. If you've only repaired a few tanks, you may have gotten impressions that you generalized to all other tanks.

Frameless glass tanks are usually constructed well, with more edges ground to be actually flat and smooth. Some don't have the inner silicone fillit seal. Since you can see how they are made, you know what you have. It used to be, when I'd visit in Europe, I'd see only frameless tanks, but the last couple times, I've noticed the framed tanks creeping in, especially with bottom frames. The top edges still are frameless on these tanks since that way they are compatible with lights for the frameless tanks.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12802571#post12802571 target=_blank>Originally posted</a> by Rhodophyta


Congratulations...

Thansk for the snarky reply, but I am very aware of the differences between trimmed and trimless tanks and their support requirement. Not only am I aware of the requirements, but fully understand they physics that dictate those requirements.

I have a couple fish hobby friends who worked for one of the first all glass aquarium manufacturers in the early 60's, and I learned enough from them to build and repair tanks starting in the late 60's.

That makes NOTHING you said in your previous post correct, it just means you have some fish friends that made tanks in the 60's.

If a tank has a plastic frame, there can always be a surprise hidden inside it, in terms of the tank construction and quality control of the glass dimensions. If you've only repaired a few tanks, you may have gotten impressions that you generalized to all other tanks.

So what? The panels are joined by silicone adhesive. It acts as a buffer between the imperfect edges on the glass panels. The trim and silicone that join it act the same way. Please do not speculate as to why MY experience is.

The trimmed tank should be set on a flat (planar) surface. Your contention that setting it on a perfectly flat pool table is dangerous is laughable. Putting foam under it does NOTHING to help those "hidden surprises".

Putting foam under the "corners' only serves to increase the stress on the joints and panels by moving the load TO those corners instead of allowing it to be distrbuted along the entire perimeter of the panels and trim. Because the foam is SOFT it will also allow torsional forces to act upon the panels and seams.

Frameless glass tanks are usually constructed well, with more edges ground to be actually flat and smooth. Some don't have the inner silicone fillit seal.

More of the same This has nothing to do with my remarks above and is instead a tangent subject.

 

[RichConley]

Just a little note here: I've seen a lot of AGA/TopFin/Perfecto/etc big box tanks where the trim itself isn't flat, and theres that gap between the tank and stand...that is until you put water in it and the tank flattens out the trim.

 

[GIJOE007]

BeanAnimal:

I think you need to take it easy on other peoples opinions and not down talk thier ideas or try and "dis-prove" them all together.

I have known many people to use foam, coark board, etc as tank underlay and have no issues to date or horror stories to tell of it.

No to say your wrong, but just becasue its not your way doesnt mean it's the wrong way!!

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12803422#post12803422 target=_blank>Originally posted</a> by GIJOE007
BeanAnimal:

I think you need to take it easy on other peoples opinions and not down talk thier ideas or try and "dis-prove" them all together.

With all due respect, If you wish to comment on my post, keep it in context to the thread. If you disagree with MY post, then please illustrate why in context to the subject, otherwise please refrain from telling me how I should communicate my ideas and interact with others. You requested that i do not "talk down" to others, but is that not what YOU just did to me? Please, lets keep this in the arena of the subject at hand


Anyway, lets not confuse OPINION with FACT. (I have used CAPITALS simply to highlihgt they key points here, not to shout or convey condescension).

My problems are with the reasoning and supporting arguments that Rhodophyta used to suggest what he presented as the FACTS. I do not (do not) agree with them and used the FACTS to explain why. It is not "opinion bashing" it is a simple matter of correcting that which is incorrect.

Rhodophyta stated that resting a modern tank on a perfectly flat surface is DANGEROUS. That is not at all true. The logic he used to support that statement is not true either. The FACT is that the tank SHOULD rest on a perfectly FLAT and HARD surface. People attempt to use FOAM to compensate for surfaces that ARE NOT FLAT.

Rhodophyta stated that glass tank manufacturers suggest putting foam ONLY under the corners. This is patently untrue. The FACT is that most tank manufacturers advise AGAINST using FOAM under the tank at all. They instead insist that the stand must be perfectly flat or the OEM stand be used. A FEW manufacturers do advocate the use of rigid foam. Again, we are talking about TRIMMED GLASS tanks, not trimless or acrylic.

Rhodophyta suggested putting foam under ONLY the CORNERS of a tank. That is bad advice posted in a public form. The fact is that supporting ONLY the corners will move ALL of the load to ONLY the corners (where it is NOT supposed to be). The fact is that using SOFT material under those corners will add torsional forces to the panels and seams that would OTHERWISE not exist on a flat stand.

The FACT is that a trimmed glass tank is designed to be supported by the ENTIRE perimeter (as much as possible, see Riches post and my comments) where the load is distributed over a large linear surface NOT point loaded on 4 corners.

Rhodophyta stated that OLD tanks have the sides built ON the bottoms and NEW tanks have the bottom suspended BETWEEN the sides. The fact is that MANY (most) new tanks are built with the sides built ON the bottom (opposite of what he posted). The fact is that MANY older tanks had the bottom suspened between the sides (opposite of what he posted).

I have known many people to use foam, coark board, etc as tank underlay and have no issues to date or horror stories to tell of it.

The issue here is with the "put foam under the corners" and the supporting arguments. Lets not get this twisted into something it is NOT.

Anecdotal evidence has nothing to do with my comments. I have seen tanks supported by cinder blocks at the ENDS only. That does NOT make it a GOOD idea or safe. It just means that somebody has done it and not had a disaster. We can come up with thousands of examples of doing things that are NOT good ideas but did not cause a disaster. Furthermore, if you poke around you WILL find plenty of examples of cracked tanks due to improper support. If YOU worked for a tank manufacturer you would see a LOT more.

No to say your wrong, but just because its not your way doesn't mean it's the wrong way!!

There IS a right way and a wrong way to do certain things. There is good advice and bad advice. There is FACT and there is OPINION. This thread is a perfect example. You are advocating accepting OPINION at any level because it is the nice thing to do. The FACT is that the ADVICE posted based on bad OPINION is bad advice.

If and when YOU see BAD ADVICE you should correct it so that other people do not head the advice and pass it along. It is how we all learn and how knowledge progresses.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=12803380#post12803380 target=_blank>Originally posted</a> by RichConley
Just a little note here: I've seen a lot of AGA/TopFin/Perfecto/etc big box tanks where the trim itself isn't flat, and theres that gap between the tank and stand...that is until you put water in it and the tank flattens out the trim.

Yup! That is certainly the case in some cases.

It becomes even more crucial that the 4 corners of the tank are FIRMLY supported and on the same plane. Twisting of the frame creates tremendous stress in the seams and panels, much more so than a gap under the span of one of the panels.

Likewise a HUMP in the long span of the stand will cause the tank force to point load at that area. This puts tremendous stress on the panels that teeter on the hum.

In other words, given the choice of an imperfection, a GAP mid-span is significantly more desirable to a HUMP and/or a non-planer stand.

 

[GIJOE007]

what are you talking about...did I not say in my post that I know people that have used foam, corak board and that it has worked without any issues???? so dont tell me that I'm not commented on the topic on hand because I am...and thats a FACT

your too much man...

 

[BeanAnimal]

Too much? You opened your post by attacking me for "down talking" peoples ideas. Something I DID NOT do. You talked down to me! I have been and will continue to be polite.

As for your foam and cork comments: Lets try some context.

You said: I have known many people to use foam, coark board, etc as tank underlay and have no issues to date or horror stories to tell of it.

To which I replied The issue here is with the "put foam under the corners" and the supporting arguments. Lets not get this twisted into something it is NOT. I was trying to ensure that we kept in CONTEXT with the other posts.

I have seen tanks supported by cinder blocks at the ENDS only. That does NOT make it a GOOD idea or safe. It just means that somebody has done it and not had a disaster. We can come up with thousands of examples of doing things that are NOT good ideas but did not cause a disaster. Furthermore, if you poke around you WILL find plenty of examples of cracked tanks due to improper support. If YOU worked for a tank manufacturer you would see a LOT more.

I very clearly pointed out that popular practice does not equate to proper practice, good results or not.

Now put that BACK in context with the entire thread please.

So yes, it is a fact that people put foam under their tanks and they MAY not crack. Nobody said ANYTHING to the contrary. That certainly DOES NOT make it good practice. It is simply anecdotal evidence to support your OPINION. Again, lets keep the comments in context to flow of the conversation.

You list yourself as an Engineer. You of all people should understand the difference between a fact based conclusion and anecdotal evidence. Your entire profession is founded in fact and logic.

I built a building with 4" steel beams even though the engineer told me I needed 6" beams. My building still stands. Is the engineer an idiot or am I just lucky? What would that engineer say if I went around telling people that 4" beams are acceptable whenever 6" beams are called for because my building still stands? What would he say when I informed him that "I know people that use 4" beams all the time and their building still stands"? Shall we use anecdote or fact to engineer beam size?

The FACTS remaim the same here and that is what I have commented on.

1) Trimmed glass tanks are designed to be supported along the entire perimeter.

2) Supporting a trimmed glass tank by the (4) corners only is NOT a good idea.

3) Supporting ONLY the four corners by FOAM is an even worse idea.

4) Many NEW tanks are made with the "walls-on-bottom" configuration, contrary to what was posted above.

5) FOAM is NOT recomended by MANY of the glass tank manufacturers, several go as far as to insist on a SOLID surface.

Please do not twist my remarks OUT of context. It does nobody any good.

 

[GIJOE007]

like I said previously...your too much :eek2:

good luck with what ever route you decide to go ukspice69 because in the end its your choice