It was suggested I ask on this forum as it is assumed more experience with large tanks would be here rather then in the
FW forum.
I have a 400 gallon custon aquarium that I will be using as
FW and will utilize two types of filtering: I will have a wet/dry setup that will skim water from the top surface - filter it and return it back into the top.
The second filtering process I need some input on. I am going to use an UG filtering system that will be gravity fed by the three existing drains in the bottom of the tank into
a filtering box beneath the tank and then pumped back up the the top of the tank. Within the filtering box would be the carbon and filtering medium. I realize that I need shutoff valves before and after the
box to facilitate shutting off the water flow when I wish to change the fitering medium. The advice I need is on fabricating the
box . It MUST be water tight so that if I should have a power failure I won't have the entire tank drain onto my floor. I am considering using an army surplus metal ammo box (as they are water tight) but I would appreciate any input as how to make it of plexi or if anyone knows of an item already made that would help. The pump I am using is a Little Giant 4-MDQX-SC. Thanks in advance for your help. Mike