Foam under your tank or sump?

[LeviT]

So I've noticed a lot of builds using some type foam looking material under their sumps and displays and since I am not ready for water yet I figured I'd ask what people have been using and why. I am considering putting foam under my sump (or around my sump since it's a tight fit under my stand) to help with noise and vibration but I am not sure what I should use or if it's worth it. All suggestions, recommendations and experiences would be appreciated. Thanks in advance!

 

[saltwatersig]

Levi

The foam I used under my tank was the garage door insulation (thanks for that info Jesse - eldiabloset8 ) and the reason was to adjust tank for any uneven floor/stand inperfections.
If you need some ....I have appx a 4 x 4 section you can have.


Sergio

 

[houser]

I'm a big insulfoam user. I got it at home depot. Check out my tank thread for inspiration!

 

[GreshamH]

That is exactly how I built the last three facilities... sitting on that stuff

 

[LeviT]

Does it help with sound/vibration at all?

 

[houser]

Probably to sone extent, but I can't tell because it's pretty loud in my fishroom.

 

[GreshamH]

Not really. Its hard to damped the sound from a massive block of water. That in itself will transmit more sound via the glass/acrylic than that of what it would via the stand.

 

[LeviT]

Thanks guys.

 

[iani]

Only use foam under glass tanks with out plastic trim on the bottom. Foam under acrylic tanks will actually cause them to bow more.

 

[GreshamH]

Only use foam under glass tanks with out plastic trim on the bottom. Foam under acrylic tanks will actually cause them to bow more.

Paint with broad brushes ofter? :lol:

Never had that issue and looking back, I have had well over 200 acrylic tanks on it. Depends on the thickness and density of the foam. My current tank has been on it for 6 years, zero bowing.

It also depends on the build of the tank.

 

[iani]

Only use foam under glass tanks with out plastic trim on the bottom. Foam under acrylic tanks will actually cause them to bow more.

Paint with broad brushes ofter? :lol:

Never had that issue and looking back, I have had well over 200 acrylic tanks on it. Depends on the thickness and density of the foam. My current tank has been on it for 6 years, zero bowing.

It also depends on the build of the tank.

Yes but there is no point to use foam under acrylic tanks if you have a decently built stand. I've seen tanks that actually bow with foam and do not bow with out foam. Since it depends on the thickness and density of the foam, can you tell people the exact foam to get? I'm sure the density won't vary between different brands of foam insulation.

 

[GreshamH]

Sounds like poorly built tanks. Perhaps get better built tanks?

You see what you want to see, thus you see no point and me stating my points will have no effect on you. I see no use in continuing this line of discussion with you.

 

[iani]

List your points, I may change my mind.

 

[rygh]

I used 3/4" foam under my big 250G acrylic tank.
Mostly for extra insulation. I used foam on the back and sides as well.
It also adds a bit of water protection on the stand in case of leaks.
Plus you can sand it flat a lot easier than wood to get those little imperfections out.
Standard Lowes construction Styrofoam.

I don't understand why it would cause bowing.
The weight of the sides of the tank is inconsequential compared to the water.
So downward pressure should be very even across the entire surface.
Thus, foam should compress evenly. And only uneven compression should cause bowing.
And the foam really should not compress anyway. A 2' deep tank is only 0.8 psi.

 

[iani]

When an acrylic tank starts to bow the downwards pressure becomes uneven. You get an increase of pressure along the vertical walls that are bowing. If the foam gives even the slightest you will get an increase in the bowing. It is much better to have a solid bottom than a semi rigid bottom.

 

[gimmito]

Gotta agree w/Ian on this one. It's one of the reasons I didn't use one on mine (+Gen did not recommend it).

 

[rygh]

When an acrylic tank starts to bow the downwards pressure becomes uneven. You get an increase of pressure along the vertical walls that are bowing. If the foam gives even the slightest you will get an increase in the bowing. It is much better to have a solid bottom than a semi rigid bottom.

I thought about that before, and thought about it even more after your post.
I really think that is backwards.
As the front bows out, the square tank becomes more like a tube.
The front bowing out should actually pull UP slightly on the front lower walls.
The tension from the outward pressure does it.
(It pulls down on the top though)

EDIT:
That last statement got me thinking even more.
As the top of the tank drops drops down relieving the tension mentioned above,
it would really reduce that force.
So most of what is left would be the simpler (but seemingly weaker) leverage force.
Basically, as the front moves outward, it puts torque on the joint with the bottom, causing
it to twist downward.
But it sure seems that the force from that torque should be minor as things flex.

Complex. I guess it all depends on how the tank is built.

 

[LeviT]

.... The corners are the most rigid parts of the tank so the walls are more likely to bow and stretch independently. That's why older acrylic tanks are bowed out words but the tops all remain flat. So if there isn't good support on the button, it can bow outward to.

 

[houser]

The way to solve this riddle is to model it on the computer!
When I ran my tank through FEA I had completely restrained on the bottom side. That's equivalent to literally gluing it to something perfectly flat, like a granite table.
So we'd need to know the material properties of say a 3/4" sheet of insulfoam - model a flat stand deck, model the foam, then the tank, make an assembly, and then run it through FEA. It's a simple task really. Of course, there's the "where's the time factor"
dh

 

[LeviT]

.... The corners are the most rigid parts of the tank so the walls are more likely to bow and stretch independently. That's why older acrylic tanks are bowed out words but the tops all remain flat. So if there isn't good support on the button, it can bow outward to.