I have always struggled with high nitrate levels, but thought after my recent move and setting up my tank again plus doing a 40% water change the NO3 levels would some how go down. This was not the case. The ammonia and nitrite levels are basically zero but the nitrate levels are still above 20 ppm? I have cut down on feeding, to see if not the problem, but do not see any difference. I have about 50kg of live rock, DSB + macro algae, my sand in the display is about 4-5cm. I only have two clowns, a cleaner w, 3 shrimps, sea cucumber, brittle star and 4 hermits in a +- 700l setup. I have read about the following products, does anyone know if it will sort out or help reduce the NO3 levels? Seachem purigen and Prodibio