• The growth of algae can be controlled by ensuring no light enters your tank. Steel tanks allow no transmission of light through the walls. A light filter can be placed under the mozzie proof inlet to almost totally eliminate light transmission into the tank.
• Consider having an AutoVacuum System installed when your tank is being made. This will assist in removing sediment from your tank. Normally when a tank is full and overflows the newest, freshest water pours out the overflow. Using an AutoVacuum system, the overflow is siphoned from the floor of the tank. Sediment is drawn away in the overflow and staler water is removed from the tank retaining the freshest water.

Excessive sludge build up indicates the maintenance of your rainwater harvesting system is inadequate. Either your roof and gutters are the source of the problem or light is allowing algal growth.