What if water is scarce?
If you have no borewater (and scheme water is too dear to dump) then you’ll need to reuse water by cleaning it. The main cleaning that needs to be done is on the nitrogen excretion product from yabbies, called ammonia. Ammonia is very toxic in very small concentrations. A reuse system circulates the Yabby tank water through a physical filter which removes organic waste particles and an aerobic biological filter (“biofilter”), containing good bacteria which “remove” toxic dissolved ammonia- they oxidize it to less toxic nitrite and then nitrate. Some types of biofilters can also act as physical filters, eg large sandbed filters. Instead of fine sand (which tends to clog), more efficient biofilters have the necessarily, very large surface area for bacteria to grow on (“bacterial substrate”) as synthetic rings, balls, etc., over which there is a thin, trickling flow of the recirculating water for better aeration. Some guidelines for these water reuse systems are: • Don’t use one if you ha
