Assertion: pool's water | /r/HasProperty | cleared through use of biological filters
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text: Ponds or swimming pools can be constructed and maintained on an organic model, sometimes called natural pools, where the water is contained by an isolating membrane or membranes, in which no chemicals or devices that disinfect or sterilize water are used, and the water is instead cleared through use of biological filters, other organisms used in water purification, and plants rooted hydroponically in the system.