questions re: building glass & acrylic tanks

I like DIY projects and I've thought about building a tank for a long time. I guess my questions here are more out of curiosity and the desire to understand why things are done than anything else.

I like glass tanks a lot for a display, I really like the fact that they are more difficult to scratch and you can get low carbon glass that give really good clarity.

My questions have to do with assembling the glass panels. I've read that the bottom panel of glass should be raised slightly off the bottom so that it does not fracture. Does this always have to be the case?
Can you not allow the bottom glass panel to rest on a flat surface so it doesn't get damaged?
Does it matter on the size of the tank? If the bottom panel is really large and there's a significant amount of weight above it (for example hundreds of gallons of water) can it not cause too much stress on the bottom panel of glass if it is not resting on a surface?

Here are the three ways that it seems a tank could be assembled:


Does it matter whether you are using glass or acrylic when you choose how to assemble?

If anyone has any experience with building a tank themselves, I would love to hear what is the right way (or should I say "best way") to build a tank.

 

Most of the rimless tanks I have see use the second method. I'm not an expert, but the first seems like it would put too much stress on the silicon in the joints. Tanks that have a frame have the glass elevated by the frame but I don't know if they use method 2 or 3. With no frame, I would go option 2. Like I said though, I am no expert this is all just my 2 cents.

 

Thanks ricoop. I just went by the nearest lfs, all of the glass aquariums had rims so it was hard to tell. There were a couple acrylic tanks that looked like they were method 3.

I guess when I've read other threads, I've seem people put down styrofoam over a plywood top of a stand. Doesn't make sense to have a raised bottom panel on the aquarium if it's not going to set down on the nice flat top of the stand!

 

I could be wrong but option 2 just makes the most sense to me for a frameless tank. As long as the stand is level that is. I would think option 3 concentrates more stress on the edge of your bottom glass and option 1 wouldn't support the joint enough.

Also I completely rebuilt/resealed my 30L. The bottom glass and frame dimensions required option 3 to be used.

 

Im building a acrylic tank the back glass is 2 and everything else is 3.

 

I am pretty sure Elos and ADA aquariums use the 3rd method of construction...with all walls on top if the bottom pane. That is how I have seen most rimless Diy builds done too.

 

Acrylic is different. When you bond acrylic you can never tell theres a
Seam so you can never tell. And glass can break. Acrylic bends. Different ball game my tanks are all 1st way but they have a rim the glass rest on the rim and the sides are them around that with tanks that do not have a plastic rim like a custom 300gal I think would be number 2

 

Did you have a reason for installing the back different than the sides and front?

 

Thanks for the replies. I've looked at some other DIY builds and I thought they also installed the side panels on top of the bottom.

It seems to me that there wouldn't be an issue with cracking or breaking the bottom panel of glass as long as it was very well supported underneath. I could see how there could be additional stress to the bottom panel if the support was uneven or maybe when moving it?

Here's the DIY where I found the info on raising the bottom panel:
http://www.garf.org/tank/GlassDirections.htm


- Jason

 

My Side panels ended up being to long and i did not want to risk cutting to short.Its only 4 gallons and im going to euro brace the top so it should be sturdy enough.