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* * * Posted by: Stephen Hopkins <watergarden@hargray.com> * * * *** Unsubscribe @ www.reefkeepers.org/cgi-bin/majordomo.pl *** Making an all-plywood tank which does not leak is difficult. The materials deform from the water pressure and the seams blow out. By the time you put in enough fiberglass cloth, epoxy or polyester resin and supports to keep it from leaking, you have spent as much as you would for a molded polyethylene tank. Since you only need 6-10 inch depth (if I read that correctly), you could use 2x12 lumber for the sides. There is a trick the soft-shell crab shedding operations use. Make the side walls (of the long axis) extend past the end walls by 8 inches and put a metal all-tread rod with washers and nuts through the ends of the end walls (outside the tank) to secure the wall joints. Put a layer of fiberglass tape (a ribbon of fiberglass cloth) on all the seams and coat everything with polyester resin. The tape and resin can be found at any hardware store or home center. The polyester resin and catalyst is about one-quarter the cost of epoxy. There is special food-grade resins which does not leach strange compounds - but it is hard to find in quantities less than a 55-gallon drum. Whether epoxy or polyester, you will want to leach the tanks for several weeks and through several changes of freshwater before use. The coating will deteriorate over time. High quality epoxies last longer than polyester, but not forever. You sould plan on having to sand, repair delaminations and recoat the tank with polyester resin in 2-3 years. However, by that time you will either have made your fortune with frag propagation or will have realized the folly and given up :>) If small leaks and water loss is an issue, I would heed the advice of the others here who suggest a plastic liner. It will be about the same price (actually a little less) with a lot less hassel and frustration. See http://www.reefindistries.com for a tough and inexpensive material. Forget the window. It will not be of much use in a shallow tank and would be a bitch to seal. To get the maximum space for the dollar, make the tank 4 ft x 8 ft. You would need: 1 sheet 3/4 inch CDX plywood 3 ea 2"x12"x10 ft lumber 2 dozen 2" deck screws 8 ea 3" lag screws 9 feet of 3/8 inch galvanized all-thread, 4 washers and 4 nuts 30 ft of 4 inch fiberglass tape 1 gallon of polyester resin with catalyst or substitute a 8 ft x 12 ft piece of cross-laminated polyester pond liner for the tape and resin About $120. SH DoughPat@aol.com wrote: > * * * Posted by: DoughPat@aol.com * * * > *** Unsubscribe @ www.reefkeepers.org/cgi-bin/majordomo.pl *** > Been having seriously difficult time deciding on what material to make (or > have made) my frag grow-out tanks out of. These tanks need not be > pretty....pure function! I'm looking for 72" X 6-10"X 24-30". The low-cost > of plywood tanks have me seriously interested. The only concern I have is > sealing the wood. I have read to use two part epoxy paints. Where the heck > can I find these? I've been to Home base...no luck. Boat store? Sure hope > not, as everything that has the words "Marine grade" seems to double in > price, despite quality :) Also, is this paint long-term saltwater safe? And > one more....I plan on 3/4" plywood. Hopefully this is strong enough. I will > put in a viewing window in the front side. If I coat the tank with enough > paint, will I need marine grade plywood? Seems to me if the wood is getting > wet, I'm screwed anyway. > > Thanks-- > Ryan Lenz
