More often the fish tank water gets dirty or cloudy.
Water gets dirty or cloudy because of fish waste, algae, white layers or food waste.
The cloudy water can cause for diseases.
Also Cloudy looks very bad. Using Grand Fish Fast Clear Crystal Water can solve the Cloudy water problem.
Use 2 ml (1 cap) for 50L water or 30 ml for 750L water which one is better.
If tank is bigger than this, then need to increase the ml as per liter. Needs to do 30% water changes on before Treatment.