Personally, I always end up with a mold in my bottle even though I put it in the fridge so I mix 1/2 TABLE with 250 ml of water and dose DOUBLE the required amount. So....in my 65 g tank I would dose 20 mL a day instead of 10.
I've never had a mold issue with my CSM mix. It could be because of chlorinated tap water. Chlorine kills mold.
Which leads me to my next thought:
Maybe adding a drop of chlorox to a 250ml bottle of solution would prevent the mold from growing. It wouldn't be detrimental to the fish since the concentrations we add to the tank are so miniscule. Just an idea;Please don't jump on me about how chlorine can kill fish. So can nitrates and we add those to the tank.
FILSTAR Pimp #2
75 gal heavily planted,50/50 Black beauty,Eco-complete substrate, Pressurised CO2 with solenoid, ph controller, AB Reactor 1000, 330 watts 9325K GE PC lighting,Ehiem Liquidoser, 2-Filstar xp3 canisters.