STICKING TO THE RULES

The bio-mechanical filter in the sump tank is working perfectly. Ammonia and nitrite levels stay very low and nitrates are under 40-80 ppm with tendency to accumulate. Bio-film of algae and bacteria growth has starter to appear at the bottom of the pond , which is desirable and will give the fish something to snack on and also improves the water quality.

 Bio-film of algae and bacteria is forming on the bottom of the pond

With all this positive water filtering, I adhere to one of the traditional ranchu keeping rules - weekly 100% water changes, or in my case more likely 85-90 %, as some water remains in the sump tank. With working filter ammonia and nitrite levels are very low, so my water changes mainly reduce nitrate level, which can't be utilized naturally and effectively in my existing system. I use municipal water and do not add anything expect the water conditioner to neutralize mainly chlorine and chloramine, which are deadly to the fish.

Even though the water can be tested for ammonia, nitrite, nitrate, pH etc. and show the "norm", there are other signs that can indicate water quality shift. Smell, color and foaming on the surface, along with how the fish behaves are all great indicators if the water change is needed. Daily fish observations are so important along with knowing how to read their behavior. Still, so much to learn here!