10-03-2015, 05:30 AM
The best way to eliminate algae from your catchment tank is to block ALL sunlight from reaching the tank. So-called 'tank covers' are porous shade cloth and admit plenty enough sun for algae to grow.
Solve the problem by buying a roll of the thick black 'construction plastic' used to cover lumber, etc. Also buy a roll of vinyl coated clothesline wire, and a small aluminum 'turnbuckle'. Remove the shade cover from your tank. Place the clothesline wire around the top of the tank and fasten it in place with the LOOSE turnbuckle. Cut a sheet from the plastic sufficient to cover the tank, and cut a small 6" hole in the exact center of the sheet for rainwater to drain through. Push the plastic beneath the loose wire all around the tank and center the hole in the center of the tank. Tighten the turnbuckle to pull the wire tight to hold the plastic in place. Pull the plastic tight around the tank, then trim it around the edges, leaving at least 6 inches all around. You may want to buy plastic 'cleats' and poly rope to hold the stretched plastic in place. Replace the shade cover.
It also helps to run a pipe from the rainwater inlet to the bottom of the tank so each rain 'flushes' the tank out the overflow.
My tank went from being too green to see the bottom, to crystal clear, by using this approach. No need for chemicals.
Solve the problem by buying a roll of the thick black 'construction plastic' used to cover lumber, etc. Also buy a roll of vinyl coated clothesline wire, and a small aluminum 'turnbuckle'. Remove the shade cover from your tank. Place the clothesline wire around the top of the tank and fasten it in place with the LOOSE turnbuckle. Cut a sheet from the plastic sufficient to cover the tank, and cut a small 6" hole in the exact center of the sheet for rainwater to drain through. Push the plastic beneath the loose wire all around the tank and center the hole in the center of the tank. Tighten the turnbuckle to pull the wire tight to hold the plastic in place. Pull the plastic tight around the tank, then trim it around the edges, leaving at least 6 inches all around. You may want to buy plastic 'cleats' and poly rope to hold the stretched plastic in place. Replace the shade cover.
It also helps to run a pipe from the rainwater inlet to the bottom of the tank so each rain 'flushes' the tank out the overflow.
My tank went from being too green to see the bottom, to crystal clear, by using this approach. No need for chemicals.