My 800Gallon Plywood Reef

[marinelife]

Update for everyone, with some warm weather hitting use I have been able to start working on this again. I have almost completely removed all silicone, exopy, and fiberglass from the bottom. I should finish this up soon and start redoing the bottom area. I will update with pictures soon!

[Miquel]

Hi
Just wondering if youve had the tank fully filled with water yet. I know you said you leak checked but not sure if you stopped filling when you detected the leak.

Not wanting at all to be negative but I must admit Im a bit concerned with regard to the pressure the walls of your tank will be subjected to. I did some some quick math. It works out like this

Water will create 1/2 pound per square inch pressure per 12" of height. For example, water in a vertical six foot pipe will exert a pressure of 3 pounds per square inch at the base of the pipe. That means that the lower edges of the tank when fully filled will be subjected to 3 psi pressure. Doesnt seem like much until you must consider the total square inches of area we are talking about. The back and front walls being 100 inches long will be subject to that 3 pounds per square inch times each 100 inches of length. Thats 300 pounds of outward force on only the bottom 1 inch of the front and back walls. The bottom 12 inches of those walls will be subjected to that 300 pounds per inch of height times 12 inches. That means just under 3600 pounds of outward force on only the lowest 12 inches of the front and back walls acting in oppositte direction which is extremely relevant as it means you will have 3600 x 2 pounds of force acting on your lowermost joints. As you move up the wall, the pressure per foot of height will decrease at a value of 0.5 psi per foot. I worked it out and the back and front walls will be subject to apr 12,500 pounds of total force each over the total area when the tank is filled with fresh water. Saltwater will increase this value by 2%. The greatest pressure will be on the lower portions of the panels. Each square foot of wall at the bottom of the tank will be subject to 3 psi x 12inches x 12 inches equals 432 pounds force per square foot.

While looking at the pictures I remembered a story my father once told me. Dad was a senior supervisor for the construction of concrete forms for major construction projects. Same general priciples apply to what you're doing. Plywood boxes designed to hold a fluid mass. I remember dad telling me once about a job he was on where an inexperienced contractor for another company had constructed forms for a large concrete pour. Dad warned him that the forms wouldnt hold and tried to explain to him the pressures the forms would be subjected to. The warnings were ignored and they went ahead. Once the concrete level reached the upper levels of those forms, they basically blew apart catastrophically. Thats what can happen

Not trying to rain on your parade. What youre doing can certainly be done successfully but you have to be sure the tank is engineered and braced adequately. The tank walls and joints will be under tremendous pressure.

[marinelife]

I have had it most of the way full, At this point I have the bottom area framed well and should not have an issue. Several have been over the PSI at the bottom and figure out wood/glue/fiberglass/nails etc so hold it together.

[marinelife]

I thought I should update everyone.
Most of the inside rework is finished, I have a few more corner pieces to add this week.
I also am getting the epoxy and will start refiberglassing the tank. This should not take to long but I will have to do some silicone work around the panel so this will have to sit and dry for a few weeks then water test it again. If all goes well I have some foam work to do and then I can swap the tanks and get this one in place.

I have also changed my lighting from MHs to SolarTubes.

One a good note, the sumps water test went well/.
Sump full of water

[Miquel]

Good luck. Hope things go well. Have you tallied up about how much the tank will have cost you when finished?

[rfanslow]

I read that you really hated to see the fiberglass lines.... Having built a couple epoxy/fiberglass/plywood boats I'm gonna show you the simple trick to hide those.. it's too late for the back wall but I do see your working on the bottom/sump atm so I figured I'd throw this out for you now. Boat Builder Central - QuickFair Compound Kit - 3 quarts - Fairing now mind you there are other ways but this is the quick (read easy) way to "FAIR" your walls and in your instance I would apply another coat of epoxy over it since you will not be priming painting like a boat would be

[Steve McKay]

I read that you really hated to see the fiberglass lines.... Having built a couple epoxy/fiberglass/plywood boats I'm gonna show you the simple trick to hide those.. it's too late for the back wall but I do see your working on the bottom/sump atm so I figured I'd throw this out for you now. Boat Builder Central - QuickFair Compound Kit - 3 quarts - Fairing now mind you there are other ways but this is the quick (read easy) way to "FAIR" your walls and in your instance I would apply another coat of epoxy over it since you will not be priming painting like a boat would be

This thread is a year old, his tank is done.