Question re. styrofoam thickness

[peathenster]

I'm getting a 72"x30"(w)x24"(h) acrylic tank. The front and back panels will be 3/4" cast acrylic and the bottom 1/2".

The stand is almost finished, but I realized yesterday that there may be a potential problem - the lip/edge is only 3/4" above the top, which is made of 3/4" MDF. That leaves 1/4" max for the styrofoam between the bottom of the tank and the top of the stand.

I think the thinnest styrofoam I'll go with is the 1/2" pink one from home depot. My question is - would it be compressed to 1/4" or thinner when the tank is full? The pressure should be similar to that of a 180g.

Need to decide whether to redo the lip (HARD) or move forward. Any input would be greatly appreciated...

 

[honda237]

I used the white styro on my 180g glass, and it barely compressed when filled. i would say less than 1/4". i can't remember how thick mine was to begin with. But maybe the pink is a different make up so maybe it will compress more.

 

[Pharaoh]

It should only compress about 10-15%.

 

[peathenster]

Thanks guys! That's bad news

So is 1/2" usually the minimum, even with 3/4" MDF and 3 horizontal 2x4s? This is what it looks like before the MDF went on:

 

[Pharaoh]

you could use 1/4". The function of styrofoam is to prevent small debris from poking into the bottom of the tank. I have actually set up multiple acrylics without using foam at all.

 

[peathenster]

you could use 1/4". The function of styrofoam is to prevent small debris from poking into the bottom of the tank. I have actually set up multiple acrylics without using foam at all.

Thanks! That's more comforting. The people making my tank are using a grayish material on top of metal stand, which looked thinner. I'll check with them to see what it is.

 

[JK47]

you could use 1/4". The function of styrofoam is to prevent small debris from poking into the bottom of the tank. I have actually set up multiple acrylics without using foam at all.

Agreed. If you shim the stand and level it well, the styro becomes less and less important. I only added the styro under my 300 because I added allot of stones but it was more precationary than anything. If your able to find 1/4" thick that would be great. Locally we only have 1/2" to 1" in precut 48"x24" sizes, the same thickness on the 96"x48" sheets as well.

BTW that's a lovely footprint Peter

 

[peathenster]

Thanks Justin. I decided to redo the trim. Annoying but probably the right thing to do.

Well when I was on the phone, the guys building my tank told me MDF was the wrong material to use under a tank, because it "soaks water like a sponge" and then expand. It's inevitable to get some water on it during WC, but I'm not going to rip the MDF off...will have to do a few coats of poly and keep my fingers crossed.

How big of a problem is it? Not talking about leak or anything, but little bit of spill during wc (e.g., going down the front panel).

 

[JK47]

Thanks Justin. I decided to redo the trim. Annoying but probably the right thing to do.

Well when I was on the phone, the guys building my tank told me MDF was the wrong material to use under a tank, because it "soaks water like a sponge" and then expand. It's inevitable to get some water on it during WC, but I'm not going to rip the MDF off...will have to do a few coats of poly and keep my fingers crossed.

How big of a problem is it? Not talking about leak or anything, but little bit of spill during wc (e.g., going down the front panel).

IMO it isn't a huge deal. I have MDF under my 120 gallon and spill all the time but it's glass. A little here and there is not going to destroy it, for sure not the best long term though. If you think it may be an issue, now is the time to rip it up and set another pieces(s) of some treated ply while you still have the chance. If it is, in any way structural, yes you have to switch it out. Warping over time is a cause of crazing on acrylic (so I've read)

I used treated plywood and styro on top o. I even have Home Depot cut the pieces for me. It's about $40 in total including the cuts, tax, styro, ply etc.. Your call bro. Here is a few pics on how I did my 96"x24"x30" if they help.

 

[Conner]

I have a 72x30(w)x24(t) acrylic tank. It just sits deirectly on top of plywood, no styrofoam. Its not currently set up, but it was set up that way for years at its previous owners house.