[Enigma]

I'm thinking about flow.

A very common practice when dealing with these cubes is to replace the stock return pump with a Maxi Jet (a 900 or even a 1200).

If the water volume is 19.5 gallons, and optimal flow rate through a "sump" (filtration chambers, in this case) is 6.1x display volume, the optimal flow rate for the return pump in this system is ~120 gallons per hour. The stock pump has a flow rate of 290 gph. Replacing the stock pump with a higher flow pump seems foolish, based on those numbers. Ergo, I'll be using the stock return pump and relying on powerheads to supply the flow that the corals require.

I've presently got a Tunze 6015 as the powerhead for this tank. While it is a little large as far as how much room it requires in the display, it is 476 gph. I need at least 20x the water volume per hour for system flow: 400 gph. Combined with the return, I'll have 766 gph, which should be suitable.

I've been testing an "Innovative Marine Spin Stream Return Nozzle" for this system. I think it is a huge improvement over the stock return nozzle: which blasts the water out and has very limited positional range.