| ● The ammonia excreted by fish becomes almost 10 times more toxic at a pH of 7.5 then it is at a pH of 6.5 ● Ammonia excretion by the fish varies through the day and can peak at over two times the daily average. ● The higher protein level of the food that you feed your fish, the greater the ammonia excretion levels. ● Fish may seem healthy at lower oxygen concentrations but food conversion and subsequently growth rate, will be much reduced. ● The pH of your water has an important bearing on how much you can oxygenate it, before other water chemistry factors become a problem. Generally at a pH of lower than 6.5 carbon dioxide will limit the fish first. Above 6.5pH ammonia becomes the first limiting factor. ● High carbon dioxide levels will limit the amount of oxygen that the fishes blood can carry. This is because if carbon dioxide levels are high in the surrounding water, the fish cannot excrete it into the water easily. Therefore, some of the blood cells - which should get rid of their carbon dioxide across the gills to make room for fresh oxygen - hold on to some of it and prevent the oxygen from being absorbed. |