Foam Under Tank / Soaking Hydrometer

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Boulder

Aquarium Advice Activist
Joined
Jun 9, 2009
Messages
167
A few quick questions ...

• As I read more and more of these 'tank build' threads, I'm learning that most people put a sheet of foam between the base of the aquarium and the top of the stand. Is this for shock absorption or to level out the surface? I didn't use any foam between the stand and tank - any detrimental effects this could cause?

• I have yet to buy a refractometer but do have a hydrometer. At first the hydrometer wasn't overly accurate, but my LFS told me to float the hydrometer in the tank for 24-hours. Being a new tank and all, I have been having my LFS test the specific gravity of my water a few times a week and my hydrometer is now remarkably accurate. How the heck does floating it in the saltwater affect the hydrometers performance?

Thanks for any insight!
 
As far as I can tell, it's supposed to relieve pressure on both the tank bottom and the stand. I've seen some use it, and some not. I'm not sure if it makes that much of a difference.
 
From what I have heard the foam does act as a shock absober and also allows some "give" to keep the tank from getting in a bind when water weight is added. It is more for keeping the glass from cracking and the seems from leaking rather than for protection of the livestock. I didn't hear about this till after I set my tank up so I don't have any other mine either.
 
I don't know the reason behind it but most of the hydrometer manufacturers instruct to soak it for 24 hours to "season" the hydrometer.
 
Putting a sheet of foam under the aquarium is a bad bad thing. It should NEVER be done. 99% of tanks were made to be supported from the edges of the tank (the trim). There is an old thread on here about a guy that had a 150 gallon reef tank break twice and it was most likely attributed to the foam that was put under it.
 
I agree with spoon, don't do it! I have only heard bad things about putting foam underneath. I was going to do it with my 30g long but opted not to after reading up a bit. The tanks are designed to take the weight on the trim and as long as your stand is level you should have no problems.

I'm a freshie so I can't answer your question about the hydrometer... hopefully the others will chime in.
 
Interesting on the 'don't do it' with the foam. On some of these tank builds people are using up to 1" of foam between the aquarium base and the top of the stand. Some use the pink stuff and others I've seen use the white beaded stuff.
 
A lot of plywood builds use it to cushion since all the weight is on the bottom piece of plywood. It's inadvisable on a commercial tank however.
 
I'm also a "don't put foam under a tank" guy, but you'll find many folks that swear it's a must. The thinking goes like this...

You need to put foam under the tank because there will be irregularities in the stand's surface that doesn't allow the tank's trim to bear 100% along the perimeter and there will be gaps. The foam fills the gaps and allows the tank to be fully supported by the stand.

I've gotten into it in another thread about this, and if I can find it again I'll post a link. But in a nutshell, that line of reasoning isn't right at all. Foam won't transfer any load in this case, but it will fill a gap.

[Edit: here's the post I was remembering... http://www.aquariumadvice.com/forums/f20/insulation-pad-or-not-104674.html ]
 
I disagree with spoon; the base piece of glass is the core component and every other piece of glass is connected to it. If you had a small tank 1-2ft then most of the weight could be distributed to the edges. However once you start getting larger the whole base supports the weight. If you place a thin piece if rubber/styrene it will flatten and if you have any imperfections in the base; and you will. Must base materials are timber, expands/contracts.

I say use it!
 
I agree with Spoonman, Foam underneath glass tanks is not recommended because it creates pressure points on the bottom of the glass where the base and stand mate causing the glass to crack (that's if the stand has a solid surface for the tank to rest on). Glass tanks are designed to be support by the edges, My 120 stand only supports the tank around the edges and center brace. Foam is suppose to be used when an Acrylic tank is being employed and even so it's usually only about 1/8 to 1/4 inch thick, this is because the acrylic tank needs to be completely supported on the bottom.
As far as the Hydrometer is concerned i find them to be pretty much useless. I had my water checked by 4 LFS's for SG and all of the readings were different and not one matched my IO Hydrometer, mind you this was done the same day with the same water. I bought a refractometer and am now confident of MY SG. IMO ditch the HYDRO and get a refractometer, It's too important to be screwing around with a notoriously inaccurate device. I'm not willing to trust a 6 or 7 dollar device when it comes to the well being of my fish. OK I feel better now.:D
If you have the time, take a container of DT water to several Shops and have them measure your SG and see what they come up with. The variations I had was from 1.016 to 1.024 with mine reading 1.026, If the window was closer I would still be using the HYDRO, but since it was so great I got confused and angry with the device. I even contacted IO regarding the problem and they just re-iterated the instructions I was already following. I'm going to try what your LFS had you do just to test it out, however this wont have me using it again because they are NG and I don't want that thing floating around my tank all of the time because I check it every day.
 
I agree with Spoonman, Foam underneath glass tanks is not recommended because it creates pressure points on the bottom of the glass where the base and stand mate causing the glass to crack (that's if the stand has a solid surface for the tank to rest on). Glass tanks are designed to be support by the edges, My 120 stand only supports the tank around the edges and center brace. Foam is suppose to be used when an Acrylic tank is being employed and even so it's usually only about 1/8 to 1/4 inch thick, this is because the acrylic tank needs to be completely supported on the bottom.
As far as the Hydrometer is concerned i find them to be pretty much useless. I had my water checked by 4 LFS's for SG and all of the readings were different and not one matched my IO Hydrometer, mind you this was done the same day with the same water. I bought a refractometer and am now confident of MY SG. IMO ditch the HYDRO and get a refractometer, It's too important to be screwing around with a notoriously inaccurate device. I'm not willing to trust a 6 or 7 dollar device when it comes to the well being of my fish. OK I feel better now.:D
If you have the time, take a container of DT water to several Shops and have them measure your SG and see what they come up with. The variations I had was from 1.016 to 1.024 with mine reading 1.026, If the window was closer I would still be using the HYDRO, but since it was so great I got confused and angry with the device. I even contacted IO regarding the problem and they just re-iterated the instructions I was already following. I'm going to try what your LFS had you do just to test it out, however this wont have me using it again because they are NG and I don't want that thing floating around my tank all of the time because I check it every day.

I think you hit the nail on the head. you have a support beam! So I think there are 2 correct answers. It all comes down to your stand and its design. solid for support!
 
I think you hit the nail on the head. you have a support beam! So I think there are 2 correct answers. It all comes down to your stand and its design. solid for support!
I bought the stand with the tank and it only supports the primeter and center support. I was going to build one but after reading around I didn't want to try (to many tanks breaking), the stand was $200 and I Made it my own.
 
Can you buy foam made specifically to put under an aquarium, made by an aquarium manufacurer? Are any tanks sold with foam to put under them? That should answer the question.
 
Can you buy foam made specifically to put under an aquarium, made by an aquarium manufacurer? Are any tanks sold with foam to put under them? That should answer the question.
I would think if the tank needed foam the manufacturer would include it with the tank. Putting a thin layer under an acrylic tank helps alleviate any pinpoint pressure spots is recommended but not necessary.
 
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