240g plywood tank questions

[anoy1nce]

Im looking to make a 48x48x24 plywood tank. I have looked the subject up and down everywhere I can find. The main question I have is about the sealant. I see some sites recommend lining the interior of the tank with fiberglass, whereas some of the people just use an epoxy sealant to the inside of the tank. Also should a tank of this size be reinforced with 2x4s on the exterior?

[frog.pauley]

I am no expert yet as I am still disigning mine.:) But through the course i have done alot of research. I fyou do not use fiber glas, you leave the plywood to be your stuctural integrity, as the plywood will be the strong point. If fiberglass is used you are making something like a plastic drum to hold water. The plywood in turn would hold alot, but be as a mold for the fiberglass, which could take alot more punishment, ie, dropped rocks and such. Fingerslake.com forums have a thread dedicated to nothing but plywood tanks. My delima at present is why to go with a potable water fiberglass, that is expensive as crap when it will be sealed with paint, maybe you can help me:)

[johno4]

The fiberglass in not needed. It helps make the tank much stronger but the you can just seal up the tank with 2 part epoxy paint. I followed the basic garf.org method and the tank has been running with no problems for 2 years. In my opinion the fiberglass is overkill, it gives people the piece of mind that the tank will hold up. Bottom line the tank doesnt need it, myself and others have proven that. Anoy1nce, I would def. use some bracing across the tank or add a Eurobrace of some sort. Good luck with your builds guys.

[dantimdad]

Definitely double up the bottom. I would use fiberglass and resin in the joints at least on something that big.

I have built several over the years and never done more than fiberglass the joints. Most of them didn't even do that.

I would, however, put egg crate down before the sand so nothing scratches the paint on the bottom. Cheap insurance.

dantimdad

[anoy1nce]

Thanks for the tips guys that's helpful.

[anoy1nce]

I do have one last question that I can't seem to find anywhere. How do I calculate how much epoxy I need?