Green water and CO2

I'm not a chemist. Can someone tell me what KNO3 is and where I can buy it
? I've been battling green water algae for a couple weeks now with no
success. I'm 2-day past a 5-day black out. I wrapped my 55gal in a heavy
blanket and duct-taped it shut. 5 days later I took it off and had crystal
clear water ! I was so happy. However, it's not been almost 3 days since I
took off the blanket, and the green water is reappearing. I was just
looking up UV sterilizers online but then I saw this post below, and I'm
wondering if that might be a fix without having to buy UV equipment. I'd
like to solve this problem as inexpensively as I can !

Thanks - Shawn


Thanks Marvin,
I have read up on UV sterilizers and was
wondering if they would be a solution. I will check it out and see what
happens.

Before investing on an equipement. kepp Light and CO2 on, dose KNO3
1/4 tsp every other day.

Just try
Dominic