[the General]

I've got an old 135 gallon I got second hand, it has a 1" thick bottom pane with 1/2" thick walls. I've had this set up for about a year, I sealed it when I got it (it was my first time and I think I did a very poor job) and it failed after 4.5 months. I re-sealed it with a THICK (~1") bead of silicone 5.6 months ago, this time doing an excellent job. Anyways last night I was looking under the tank for some reason and noticed that the bottom pane is not supported at all! It's attached about 3/16" ABOVE the level of all the walls. I have an old metal stand which supports only around the sides and a center brace, but nowhere is the bottom pane actually in contact with the stand, only the walls.

This makes me a bit nervous to say the least; if I'm not mistaken, ALL of that 1200ish+ lbs of load is being transferred through the silicone to the walls to be supported. Is anyone else's tank made this way? The way the plastic trim is molded it seems like the pane is supposed to be fit like that to the walls, but that just seems like a silly way of making something that has to support that much weight.

So should I be concerned? Took me long enough to notice this, eh?
Either way, thanks for reading!

 

[mithesaint]

I'm going through the EXACT same thing right now. I think we have the same tank :lol: A few more days and I might be ready to try to reseal my own 135 fixer upper.

Look at the rest of your tanks, and you'll feel better. The rest of mine are the exact same way, so apparently it works. It just seems counterintuitive to those of us who don't know better. McDaphnia has a nice discussion on tank building styles in my 135 fixer upper post. I'd link it, but I'm lazy :thumb:

Hey, it's holding water, right? :thumb:

 

[MalawiLover]

If you look at the bottoms of almost all commercially constructed glass fish tanks the bottom pane will be "suspended." The commercial stands as well only support the walls of the tank. The plastic frame helps some, but for the most part the weight of the bottom, substrate and decor are supported by the silicone and transfered to the stand only by the walls.

 

[danielratti]

The reason that the bottom is suspended from touching the fram is all it takes is on little flaw in your tanks stand to casue your tanks bottom to shatter or spider web out from the pressure from the tank pushing down on to that flaw.

 

[the General]

You have all both put my mind at ease and VASTLY increased my mental stability. I was going to go crazy if I had to break the thing down again, put the fish in temp tanks, and redo it all.

Right after I posted I looked at my store bought 75g and it similarly had a raised bottom, and what danielratti said,

The reason that the bottom is suspended from touching the frame is all it takes is on little flaw in your tanks stand to casue your tanks bottom to shatter or spider web out from the pressure from the tank pushing down on to that flaw.

, makes an awful lot of sense. Also upon further reflection, silicone's grip on glass is pretty extreme, and THAT MUCH silicone probably can take that kind of constant force without much trouble.

Thanks everyone for your input!

mithesaint how much did you get your fixer upper for? The people who sold me mine were clearly desperate to unload it and gave it to me with the stand and a ton of filter stuff, and a canister filter in decent shape, for just 100 bucks. The wonders of craigslist!

 

[mithesaint]

mithesaint how much did you get your fixer upper for? The people who sold me mine were clearly desperate to unload it and gave it to me with the stand and a ton of filter stuff, and a canister filter in decent shape, for just 100 bucks. The wonders of craigslist!

You did better than I did, that's for sure. I'm cursed with expensive used tanks around here. You know, people selling 10 gallons for $25, 55 gallons with stand and light for $200, etc.

I paid $65 for just the tank, and gave the guy an extra $25 to bring it to me (30 miles or so), so $90 total. No filters or anything else, which is fine because I'll do a DIY sump and I do my own DIY stands.