Delicate Sounds Moon Walker Kush

Week 3 flowering: smooth sailing, flowering leds switched on, put a net over. Let's rock and roll! Accidentally dropped my hygro/thermo in the water. RH now 99%. 😜 Now 2nd stage of flowering is near, I'd love to add some Cannaboost to my solution. However, there's a bit of brown algae contamination in my tank (of which I can't seem to get rid of, despite cleaning the tank with and adding hydrogen peroxide to the tapwater (pH 7.9, EC 0.3) I use to make my solution). Cannaboost seems to worsen the problem.