Jardiniboy, the extra foam in front of the pumps is very fine and thick, it collects massive amount of fine particles and waste, the reason I use the foam is that is easy to clean and re-usable. The foam at the beginning of the filter is large porosity and collect big waste before the bio balls. Nitrates in the tank are now down to 20 mg/L and still dropping slowly

. The sulfur reactor is denitrating 40 gallons a day

and only been running for 4 weeks. I had used coil type before, I must have done something wrong because everytime it started to work they would plug off. If I build another one I think I will use large hose, and maybe 2 Aqualifter pumps in series for extra pumping power.
Just for fun here's a few pics of the filter.
Happy New Year