Hybrid Concrete and Glass 120 gallon tank build
I am in the early planning stages of a 120 gallon aquarium build. I have been calling around to my local glass and mirror companies but generally they are quoting me a price between 650 and 1000 dollars for 1/2" thick annealed glass. This does not include euro bracing which this type of aquarium would need. Online the cheapest price I found by a lot was glasscages.com which quoted me a price of 365 for the glass (no polishing on the edges) but 250 dollars for shipping (again not including euro bracing).
Then I hit on the idea of taking apart an older used aquarium (or likely aquariums) and re-using the glass since the older ones are made of 1/2" glass. This unfortunately has not worked out; there seems to be a real lack of supply in my area. The few that exist the owners seem to want near as much as a new aquarium would cost.
At last I hit on the idea of making an aquarium out of concrete for 2 of the 5 sides. Specifically the back and the bottom. The remaining 3 sides would be made of glass. Because I plan to use concrete for the back and bottom it would allow me to use pre-made tempered glass panels for the remaining 3 sides. Why pre-made tempered glass panels? Because they are incredibly cheap by comparison. These are panels designed to be used for table tops. I can get a 24x48 panel made of 1/2" tempered glass for around 120$. Each 24" square side costs around 70$. So for about $260 I can get all the glass I need for the aquarium. Concrete will likely run me somewhere between 60$ to 100$ depending on how much I need. Grand total of 360$ not including silicone.
The major negatives to this idea are 1) I haven't seen anyone do this on a small scale. Large scale concrete tanks are everywhere, small scale... not so much. So I would be forging a new path with something that I really don't want to explode in my house. 2) This is not the path to instant gratification, concrete will take 28 days to cure plus additional time waiting for sealants to dry etc. 3) This method requires a lot of research on my part since concrete is far more complex then glass, I need to learn a lot about what kind of concrete is best, and also best methods of preparation. 4) I will need to do test pieces before I can be satisfied this will work which will add additional time to the project. 5) The aesthetic will not be one everyone will enjoy. Personally this is not a negative for me since I am sure I will enjoy it since my theme from before I hit on this idea was to make what I am calling an urban nature aquarium that will include items from both nature and the modern world.
That gets me up to present. What I would love to know from anyone who has built using concrete before, is whether silicone will stick to concrete that has been sealed? My plan is to create a channel in the base and back of the concrete for the glass to sit in, and silicone it in place. This will give me an additional bracing method on the bottom and back of the aquarium. But, will silicone stick to the concrete after I use some method of sealant on it? I have seen large aquariums use epoxy coatings so I was thinking I would do the same. I just want to make sure it will stick.
I am at this point not planning on doing any kind of euro bracing for this aquarium. Instead I would use angle aluminum on the two exposed corners to increase my silicone coverage. That plus tempered glass and the channels I plan to make in the concrete as additional bracing are my plans for holding the tank together. I realize I am forging my own trail here and that no one has done this before (to my knowledge anyway), but if anyone has worked with silicone, glass, and concrete together I would very much appreciate any advice you have.