I have a 6 footer tank with a 4 footer sump.
I regularly change my water once eveyr month.
I will change the whole of my sump tank water and wash my skmmier cup
However, whenever i change my water, some of my fishes will get fin burn and ich.
Some will survive however, those new intro fishes, though they have been eating and in my tank well, will sometime not able to pull through after few days of WC.
Can any expert advise me?
1) Is it that I change too much water at once?
2) should i change to twice half sump tank amount?
3) what are the precautions to take; what are the parameter to check?