I never cleaned the reservoir until the end of grow. EVen in commercial
greenhouse we never clean until June when we shut down for the Summer.
When I clean I use common dishsoap and a sponge with scotch brite on one
side (green). Rinse really well, and if you want buy some kleerex or
other flushing/leaching product. I also clean my hydroton the same way.
I soak hydroton in a bath of Kleerex or other commercial flushing
agent.These flushing agents dissolve salts and allow hydroton to be used
over and over. I have a friend who used his so long that it is now