We just inherited a house that has a 4000 gallon koi pond. I have no idea about any of it. I know I need to add salt somehow and stuff to kill algae and keep live off the fish but not sure when how much etc......it has a big tank that has air pump hooked to it and it bubbles when on and drains to the waterfall. It hasn't been treated in over a week and is very cloudy with green muck! Help I have been feeding skimming and cleaning out skimmer fish cone eat everyday!!!! Please any help at all??