Cloudy Water For Second Time In 2 Monts

[zapperjack]

hi, can anyone help my tank has gone cloudy again this is the second time in two months. worried as the first time this happened overnight I lost 3 fish and the tank smelled of rotten eggs. The tank is 6 months old, and has now been cloudy for a couple of days, it does not smell this time but a guppy died this morning. Did a water test all ok except high alkalinity.
Please help I don't want to lose any more fish

 

[Curiosity101]

All you can really do is make sure the water stays well oxygenated.
The bacteria that cause the bloom are aerobic and therefore use up oxygen. This can then cause stress and/or death to the fish in the tank.