Ponds 101 Chapter 9
The Biological Filter
OK, the pump is in the skimmer, the water leaving the skimmer has been pre-filtered, all the large debris removed before it can sink or clog the pump, but what about all those small pieces of debris and finer particles that are going to pass right through skimmer and pump and head up to the waterfall? This is the place for the Biological Filter, packed with various filter media that mechanically remove the tiniest particles in the water and provide a substrate for bacteria that literally eat toxic nitrites and ammonia from fish wastes before they can build up and start poisoning the water.
Water enters at the bottom into an open void that allows for heavier sediments to settle out, while finer particles are forced through various stages of coarse, medium and fine media that remove the particles and provide tremendous surface area for bacterial colonization, under the most ideal conditions. Nitrifying bacterial colonies on the surfaces of the media convert the toxins in pondwater into harmless nitrates efficiently and continuously, keeping water quality excellent. Unlike in skimmers, where the water is drawn through mats or pads by gravity alone, the powerful hydraulic pressure the pump produces keeps water moving through the pads, mats and particulate media of the biological filter for an entire season before it needs cleaning, drastically reducing maintenance. Since the more clogged the media gets, the finer the particles it filters, a properly functioning biological filter keeps pond water quality excellent, crystal clean and gin clear, provided the nitrates are properly dealt with, but more on that in the next chapter. Biological filters such as the Atlantic Water Gardens FilterFalls also provide a fast, easy and leak-free way to attach the pipe from the skimmer to the EPDM liner, creating a broad waterfall and avoiding the dreaded “hose-under-a-rock” look that plagues beginner builders. See Biological Filtration 102 - Chapter 2 in the College of Filtrationto find out more.
OK, the pump is in the skimmer, the water leaving the skimmer has been pre-filtered, all the large debris removed before it can sink or clog the pump, but what about all those small pieces of debris and finer particles that are going to pass right through skimmer and pump and head up to the waterfall? This is the place for the Biological Filter, packed with various filter media that mechanically remove the tiniest particles in the water and provide a substrate for bacteria that literally eat toxic nitrites and ammonia from fish wastes before they can build up and start poisoning the water.
Water enters at the bottom into an open void that allows for heavier sediments to settle out, while finer particles are forced through various stages of coarse, medium and fine media that remove the particles and provide tremendous surface area for bacterial colonization, under the most ideal conditions. Nitrifying bacterial colonies on the surfaces of the media convert the toxins in pondwater into harmless nitrates efficiently and continuously, keeping water quality excellent. Unlike in skimmers, where the water is drawn through mats or pads by gravity alone, the powerful hydraulic pressure the pump produces keeps water moving through the pads, mats and particulate media of the biological filter for an entire season before it needs cleaning, drastically reducing maintenance. Since the more clogged the media gets, the finer the particles it filters, a properly functioning biological filter keeps pond water quality excellent, crystal clean and gin clear, provided the nitrates are properly dealt with, but more on that in the next chapter. Biological filters such as the Atlantic Water Gardens FilterFalls also provide a fast, easy and leak-free way to attach the pipe from the skimmer to the EPDM liner, creating a broad waterfall and avoiding the dreaded “hose-under-a-rock” look that plagues beginner builders. See Biological Filtration 102 - Chapter 2 in the College of Filtrationto find out more.
