I am helping a friend set up a 79 gallon freshwater planted tank. The tank is a hollow cylinder of acrylic and has two holes drilled in the bottom. The stand is a hollow cylinder of ABS plastic (salvaged culvert section). My friend wants all equipment/plumbing hidden below the tank inside the stand.
We already bought the following equipment from Rainbow LifeGard: Quiet One 4000 HH pump, AF-94 mechanical module, AF-93 chemical module, AF-92 heater module, QL-8 UV
sterilizer. The manufacturer, Pentair Aquatics, told us that the chemical module would not hold enough biomedia to support a heavily stocked tank of this size. We therefore ordered the FB300 fluidized bed filter and intend to substitute it for the chemical module.
A tech person that I spoke to recommended that I put the FB300 filter last in line with a "short circuit" around it made of two tee connectors and a ball valve. The purpose of the short circuit is to regulate the flow through the FB300.
I told a friend about this setup scheme. He said that the FB300 should be put before the UV
sterilizer so the bacteria can colonize it. He said that even if I only plug in the sterilizer after the tank has cycled, the sterilizer will prevent bacteria from continually recolonizing the FB300.
Is he right? Do nitrifying bacteria recolonize the biofilter via the water column or via basic cell division on the substrate? Should I put the FB300 before the sterilizer?
I have another concern as well. A tech person told me that the soft plumbing will spring a leak if the pump fails or their is a power outage. She said that the water pressure on the system will be too great. Is she correct? Am I flirting with disaster? Note: the tank is 22 inches in diameter and 42 inches tall.