Designing a sump, for my 75g, using a 20g glass tank. I want this to be both a refugium (for macro-algae to eliminate nitrate and other waste), as well as provide enough bio-filtration that I can remove my HOB
I have about 20lbs of LR
in the main tank now, adding more all the time, but I won't have the 1.0 to 1.5 pounds/gallon needed for LR
filtration for some time.
In my design so far, basically there's a suspended area on one end for bio-balls or rubble, a baffle next, which overflows into the main/refugium area. The height of that baffle will depend on if I want to submerge my filter media (bioballs or rubble).
The refugium will be about 1/2rd the tank, leaving about 1/3rd for return pump and future skimmer.
I figured 2g of bio-balls would be enough for a 75g (since each g of bio-balls are supposed to handle 45 to 60 gallons).
rubble, filling the same amount of space, be as or more effective? Is it best to have rubble wet/dry/trickled, or submerged? If it should be submerged, I can turn the rubble containment area into a corner box or something.
For 2g of bio-balls, I'm allocating an area 4.5" wide x 9" tall x 12" depth, or 526 cubic inches.
If I use LR
rubble, in the wet/dry section (where water trickles over) is that enough LR
, or should I increase the space allocated?
Or, is LR
I want to have a large volume for potential overflow in the event of power or pump failure. If standard operating water level in the sump is 3", that will give me about 15.4 gallons of overhead, should the pump stop returning water to the main. That's about 3" of water in my 75g, which should be very easy to work with.
With 3-5" of water in the main area, that's about 4.6 gallons contained in the sump, half of which would all be pumped to the main tank if the siphon fails. That's barely over an inch of water to the main.
So, I'd operate the tank about 1 inch below the very, very top of the tank, and never have to be concerned with overfilling the tank. With the overflow siphon in the tank setup with about 1" of water over the "spill" level, I'd never have to worry about the sump overfilling.
There'd be lots of leeway on either side. I'm not getting the benefit of adding a huge volume of water to the system (around 5 or 6 gallons total added), but it should be effective bio-filtration, a good place for a heater and skimmer, and I'd also not have to worry about flooding.