foam under standard glass tank

[ADreef]

I know this is a somewhat controversial subject, but please read my post before responding. Sorry in advance for the wordiness of this post.

I have read many of the past threads that discuss this, but most seem to refer to putting foam under the plastic trim while keeping it from touching the glass (BTW, the tank is a standard 100g - 60x18x24). What I want to do is cut foam that fits completely inside the trim and touches only the glass. Therefore the entire bottom glass (minus the half-inch or so perimeter covered by the plastic frame) would be supported by the foam. The foam would be thick enough so that the plastic frame would not touch the stand. From a mechanical standpoint, it seems to me that fully supporting the bottom glass would add to the factor of safety of the whole tank since the bottom panel would no longer be flexing to support all the tank contents. Maybe I'm missing something, but I don't see how this is any different than using a piece of foam under a frameless glass tank. After all, it's still basically the same 5-sided glass box whether it has the plastic frame or not. No?

From what I understand, the plastic trim on MOST (but not necessarily all) tanks is primarily there to cover up the unpolished edges of the glass panels and to possibly aid in assembly. It also protects the edges from getting chipped or otherwise damaged. I can see it adding strength to smaller tanks, but not larger ones. It adds labor and therefore $$$ to grind and polish the edges of the glass panels, so I can understand how the plastic trim could keep the tank under a certain price point.

My only real motivation for considering this type of setup is to make the tank less likely to fail. If I dump 100+ gallons of saltwater on our wood floors, that might be the end of my hobby in my wife's mind. I have done a fair amount of woodworking, plus I'm kind of a perfectionist and tend to overbuild things, so building a flat, level stand won't be a problem. That being said, wood can change it's shape over time and with changes in humidity and temp. My floors can also settle under the weight of the tank. Plus, I live in earthquake country. I'd like to do anything I can do to make the whole thing more stable and not have the tank try to follow any minor stand distortions that might crop up later.

I'm well aware that most manufacturers say not to put foam under their glass tanks. While I trust that they know what they are doing, I don't really trust that they are going to give me an honest answer on this subject. They have business liability to think of.

I do agree that having foam under the entire tank structure (including the plastic frame) may be a bad idea IF the center of the bottom glass panel ends up pressing on the foam. However, I really can't see any problem with fully supporting only the glass itself like I describe above. If anyone has done this with their standard glass tank, I would like to hear about - good or bad experiences.

And please, don't respond unless you have some actual experience (or know someone who does) or have some type of engineering-related explanation of why it should or shouldn't work. I'm not trying to be rude here - I'm just trying to weed out any "the common practice is..." or "call the manufacturer" type of response that has filled up other threads on this subject.

Thanks!

[James404]

Off the shelf tanks with black trim are designed to be supported at the corners, also the trim adds structural integrity. I think you are overthinking this, you should have no problems with the tank resting directly on the trim.

[ADreef]

I do tend to over think things from time to time.

you said:
"Off the shelf tanks with black trim are designed to be supported at the corners, also the trim adds structural integrity. I think you are overthinking this, you should have no problems with the tank resting directly on the trim."

I can see how the trim could add some integrity to smaller tanks, but not so much with large ones.
If this were a large piece of furniture, or a house, or some other complex structure we were talking about, then I would be willing to believe that it is designed to be supported at the corners.
You're going to have to explain to me how a fish tank is "designed" that way.

[Zimboy]

Originally Posted by ADreef

I do tend to over think things from time to time.

you said:
"Off the shelf tanks with black trim are designed to be supported at the corners, also the trim adds structural integrity. I think you are overthinking this, you should have no problems with the tank resting directly on the trim."

I can see how the trim could add some integrity to smaller tanks, but not so much with large ones.
If this were a large piece of furniture, or a house, or some other complex structure we were talking about, then I would be willing to believe that it is designed to be supported at the corners.
You're going to have to explain to me how a fish tank is "designed" that way.

Tanks with floating bottoms are designed to sit on the side panes of glass, not on the bottom pane. The bottom pane in these tanks is designed to "float", with the weight of the tank transferred to the stand thru the vertical panes of glass. Have a look at the stock stands and you will notice that they only support the edge of the tank. The bottom pane is truly "floating". Now, I am not an engineer, although I wanted to be one when I was a kid, but it seems that tanks with the bottom trim are designed to be supported on the edge, and changing that is going against the stated usage of the tank. But to each their own, it seems you may be looking for confirmation bias to pop up for you, so good luck with that.

[billdogg]

Take the trim off the tank - you will find that the sides do not rest on the bottom pane - rather, the bottom pane is sandwiched between the four sides. Doing as you suggest will support the bottom pane quite well, but will lead to bottom seam failure when the weight of the sides eventually (sooner rather than later) breaks the silicone seal.

[jim.l]

I used to always put foam under my tanks (the trim would sit on it). However I read the warranty on my current 150 aga tank. The warranty is voided if anything is under the tank. I assume that they feel its a bad idea.

[ADreef]

My tank is a Visio, make by Advance Aqua. They say right on their website (http://www.advanceaquatanks.com/vg.html) that the vertical panels sit completely on top of the bottom panel. Thus, the bottom panel supports everything. They refer to it as solid bottom construction. I have read elsewhere that this is common of many US manufacturers. The floating bottom design is more common in Europe and Asia.

[ADreef]

Originally Posted by Zimboy

Tanks with floating bottoms are designed to sit on the side panes of glass, not on the bottom pane. The bottom pane in these tanks is designed to "float", with the weight of the tank transferred to the stand thru the vertical panes of glass. Have a look at the stock stands and you will notice that they only support the edge of the tank. The bottom pane is truly "floating". Now, I am not an engineer, although I wanted to be one when I was a kid, but it seems that tanks with the bottom trim are designed to be supported on the edge, and changing that is going against the stated usage of the tank. But to each their own, it seems you may be looking for confirmation bias to pop up for you, so good luck with that.

Actually, I am an engineer. I have a degree in mechanical engineering (although I've somehow managed to become a software guy nowadays) - that's why I'm having a hard time with this. My tank does not have a floating bottom, and thus I have a hard time believing that it is "designed" to be supported only on the edges or corners.

[James404]

Originally Posted by ADreef

Actually, I am an engineer. I have a degree in mechanical engineering (although I've somehow managed to become a software guy nowadays) - that's why I'm having a hard time with this. My tank does not have a floating bottom, and thus I have a hard time believing that it is "designed" to be supported only on the edges or corners.

Interesting, so your tank is not a floating bottom but the manufacturer uses a bottom trim that when on the stand only puts weight on the perimeter? Perhaps I'm wrong but from my understanding, that is not a good idea. When all the sides sit on the top of the bottom glass, usually you have to have foam on the bottom to distribute the pressure evenly.

[Zimboy]

Originally Posted by ADreef

Actually, I am an engineer. I have a degree in mechanical engineering (although I've somehow managed to become a software guy nowadays) - that's why I'm having a hard time with this. My tank does not have a floating bottom, and thus I have a hard time believing that it is "designed" to be supported only on the edges or corners.

This confused me at the start. Most tanks that have a trim are a floating pane on the bottom. As James404 stated, having that trim on the bottom will put undue stress on the edge of the tank when sitting on a regular stand. However, if you are putting the foam on the glass not enclosed by the trim, won't that also create shear forces on the edges of the glass not supported by the foam, especially if you believe that the trim adds no structural support?

FWIW, the plastic trim on my 130 fresh is most definately adding to the structural integrity of the tank, however, that tank has a true floating bottom...

[ADreef]

Originally Posted by Zimboy

This confused me at the start. Most tanks that have a trim are a floating pane on the bottom. As James404 stated, having that trim on the bottom will put undue stress on the edge of the tank when sitting on a regular stand. However, if you are putting the foam on the glass not enclosed by the trim, won't that also create shear forces on the edges of the glass not supported by the foam, especially if you believe that the trim adds no structural support?

Sure, if I have a tank where the bottom panel is under the sides and I put foam under the glass inside the plastic trim, there will be some shear force on the edges of the bottom panel caused by the weight of the side and end panels (around 130lbs on my 100g if it's 3/8" glass), plus the weight of the hood and its contents (maybe 50lbs). But what about when the same tank is set up normally, i.e. resting on the plastic trim? In that case, the edges of the bottom panel are supporting all the weight, and the contents of the tank (850lbs or so if only saltwater) will be putting quite a bit more shear force on basically the same part of the glass (right near the inside edge of the trim piece).

[ADreef]

Originally Posted by Zimboy

FWIW, the plastic trim on my 130 fresh is most definately adding to the structural integrity of the tank

If I may ask, how do you know that for sure?

[OregonReefer]

Originally Posted by ADreef

If I may ask, how do you know that for sure?

For one thing I'm sure the lower center brace serves a purpose just as the top one does... If the frame doesn't add to the integrity of the tank it's just added cost...

Businesses don't add cost and tell you to set it up wrong just so they can replace the product (not to mention the possible out of pocket expenses for liability)

The obvious question is: If the manufacturer thought they would have less liability by telling you to put foam under the glass why would they void the warranty if you do?

Here's your choices

Setup the way YOU think it should work better, void your warranty and any potential reimbursement by the manufacturer and, well, there goes the hobby because.... you're doing it wrong!

Or set it up the way the manufacturer tells you to...

BTW, your skimmer will not work better in your DT

[ADreef]

Originally Posted by OregonReefer

For one thing I'm sure the lower center brace serves a purpose just as the top one does... If the frame doesn't add to the integrity of the tank it's just added cost...

Businesses don't add cost and tell you to set it up wrong just so they can replace the product (not to mention the possible out of pocket expenses for liability)

The obvious question is: If the manufacturer thought they would have less liability by telling you to put foam under the glass why would they void the warranty if you do?

Here's your choices

Setup the way YOU think it should work better, void your warranty and any potential reimbursement by the manufacturer and, well, there goes the hobby because.... you're doing it wrong!

Or set it up the way the manufacturer tells you to...

BTW, your skimmer will not work better in your DT

That piece of plastic is cheap to manufacture. Grinding and/or polishing all the edges of the glass (like you would find on a nice frameless tank) is time-consuming and therefore expensive. Putting that piece of plastic on the top and bottom obviates the need to make all those covered edges pretty. The plastic frame would also protect the edges and make the tank easier to handle and easier to ship. So, my contention is that the plastic frame is not added cost but actually makes the tank quite a bit cheaper.

As far as the manufacturer and warranty - I will be voiding it anyway when I build my own stand for the tank. Most manufacturers will void it if you don't use their stands. It's in their best interest to try and limit the possibilities of what someone might do with their tank to limit their liability.

Originally Posted by OregonReefer

... you're doing it wrong!

No, I'm just not doing it according to gospel. If someone can show me a valid reason why it won't work, other than just telling me I'm wrong and they're right, then I'll change my mind.

Originally Posted by OregonReefer

BTW, your skimmer will not work better in your DT

Uh, what?

[James404]

Have you actually spoken to the manufacturer and see what they are recommending? In the beginning of this post I think most of us assumed that you where using one of the "big" manufacturers tanks such as Aqueon/AGA, Perfecto etc... With the way they say your tank is constructed I think it would be wise to use the foam as you stated.

As far as the trim adding structural integrity to only smaller tanks and not larger tanks, try cutting the center brace on a 90g Aqueon or Perfecto tank and see how much bowing occurs, and yes they put braces across the bottom of those tanks too, thats not just to cover up unpolished edges.

[jeff@zina.com]

Originally Posted by ADreef

I do agree that having foam under the entire tank structure (including the plastic frame) may be a bad idea...

I've had foam under all my tanks, plastic-rims and all, for decades. Never had any issues. I'll continue the practice as long as it works for me.

Jeff

[ADreef]

Originally Posted by James404

Have you actually spoken to the manufacturer and see what they are recommending? In the beginning of this post I think most of us assumed that you where using one of the "big" manufacturers tanks such as Aqueon/AGA, Perfecto etc... With the way they say your tank is constructed I think it would be wise to use the foam as you stated.

As far as the trim adding structural integrity to only smaller tanks and not larger tanks, try cutting the center brace on a 90g Aqueon or Perfecto tank and see how much bowing occurs, and yes they put braces across the bottom of those tanks too, thats not just to cover up unpolished edges.

I sent them an email, but have yet to receive a response. I have heard that they aren't particularly responsive. I will try calling them before I get started on this project.

I guess I should have reiterated the "most, but not necessarily all" as I did in my first post with regards to the manufacturers. I was aware that some had plastic frames with center braces. That would definitely add some strength on the top of a tank, and maybe the bottom also. The bottom frame on my tank does not have a center brace.

[ADreef]

Originally Posted by jeff@zina.com

I've had foam under all my tanks, plastic-rims and all, for decades. Never had any issues. I'll continue the practice as long as it works for me.

Jeff

Jeff,

Thanks for the reply. It's good to hear from someone who has done something like this.

Do your stands have a solid or open top? I guess my only concern with having foam under the trim and glass is if it were on a solid top stand - MAYBE if the center of the bottom glass bowed enough to press into the foam, then this would create a pressure point since it would be supported unevenly? Maybe?