RDSB
RDSB
Unfortunately a plastic cup will not cut it. In order for a RDSB to work, you need to promote the growth of bacteria which cannot grow in the presence of oxygen. A RDSB achieves this by being deep enough that oxygen cannot reach the bottom of the sand bed. I believe that if you use a sugar fine sand, you need at least 6 inches of sand deep. Anything more than 20 inches is a waste. It is also very important that the sand is not disturbed. You have to make sure that the water flow across the surface on the sand bed is slow enough that it does not carry sand away with it.
On my 65 gal reef, I have a 6 gallon oceanic salt bucket with 50lbs of #1 sand in it. I use a Maxi Jet 400 to supply water to the surface of the bucket and it drains by gravity back to my sump. It is important that both the water and the drain are at the top of the bucket. It took about 2 months for my bucket to mature, but once it did my nitrates dropped from a consistent 15ppm to ZERO.
