fish dying (long Post)

[pinhead]

If they are fine during the day but are dead in the morning it is not your water parameters.

I would think that the oxygen levels are too low at night as the Corals and Macroalgae switch from photosynthesis to respiration. During the day they are using Carbon dioxide and producing oyxgen and at night the reverse occurs. The carbon dioxide produced at night is the reason pH also fluctuates between day or night.

Without an easy way to measure oxygen levels, the simple solution is to run an airstone at night or point some extra powerheads at the surface of the water for better gas exchange and into the rocks to prevent areas of low oxygen.

Try these simple solutions before you worry about your water.