How do I build a 75 Gallon fishtank?

Answer 1

"With all due respect" to the prior answerers, I don't think you have gotten good advise.

this is not a run down to Home Depot and grab some material type thing. The final cost may be greater than the cost of a store bought model. You might find a used one even cheaper....

how ever lexan is spelled it is a "GE" tradename and is really just another name for polycabronate. http://en.wikipedia.org/wiki/Polycarbonate

Besides the weight already mentioned there is the water pressure [much stronger at the bottom] that must be considered. The water is trying to push the pieces apart and if there is any flaw in the seal it could break. there is also a chance the material could begin to bow along the top edge from this pressure. Next the weight of water is between 62 and 64 pounds a cubic foot, so the water would weight about 620 pounds freash water to 640 pounds if it is salt water, PLUS the weight of the tank. The type of water will affect the selection of material. Some plastics don't like salty water.

A tank can be make in any shape or form you want as long as you use the right materials, there is no magic formula.

Here is a link to a how to page. As you can see they give a list of possible materials. 1/4" glass, without it being laminated, tempered or hardened, would NOT be my choice.

http://www.austinglass.com.au/aquariums.html

by the way, putting on the sealant and assembling method can be very difficult, much better and easier to pre-assemble with spacers and then add sealant.

a few thoughts on the sealant, it needs as much surface contact with the panels as you can provide, so do cove it between the panels. it is difficult to "clean up" so one thing you can do is mask off a line close to the joint and remove the tape before the sealant cures. you would strike down the coving of the sealant to the masking and carefully pull the tape as soon as you are done "working" the joint.

the most important quote from the link is, "I cannot emphasis enough the need to get the engineering right", you don't want to have a failure with 75 gallons of water. Don't forget that the supporting stand needs to be constructed for the weight and the floor below should be looked at and additional support[s] added id needed. Most homes are NOT constructed for this type of concentrated load.

Answer 2

With all due respect it's "LexAn, and 75 gallons of water weighs approximately 638 pounds, and obviously needs to be supported as such. Any TYPE of plexi in a 75 gal. tank would likely be more flexible than glass as usually sold. Certainly plexi products come in greater thicknesses than window pane. Lexan is a stronger form but..........

I used to build my own for salt water aquaruiums, and used Glass.

There are formulas obviously that dictate measurements of the material used, which will then offer you what height, length, width, you can choose. Certainly you can also go to a shop that sells them and take measurements.

For 75 gallons I'd use glass, and perhaps as thick as 1/4 inch. Then I use clear silicone, "designed for the purpose". I build the tank two pieces at a time, squaring the pieces, squuezing a bead of silcone at the edge, pressing the opposing piece to that bead at a 90 degree angle, and wipe excess from the exterior and interior. I clamp the work until the silicone cures. I have used tape but that leaves residue often.

When the two pieces are secure I seal them to a bottom, allow that to cure, then add the 4th piece, 5th piece, and build a frame for the top and bottom.

An initial test might mean using no more than 10 or 20 gallons of water checking for leaks.

Steven Wolf

Answer 3

Get some lexon, some epoxy & go to work. Try to have the lexon cut at a crafts store before you bring it home. Several manufactures offer pump kits & a light. Just add water . . .