Use regular, unscented clorox (or generic brand) bleach. Regular bleach. Don't get the non-foam. Plain bleach. Active ingredient is 8.25% sodium hypoclorite.
8.25% means 82,500 PPM sodium hypoclorite from the original bottle.
Make a 20% dilution of 1 part bleach to 4 parts water. This will be your stock solution, 16,500 PPM sodium hypoclorite. (82,500 * 20%)
There are 3,785 mL per gallon.
Which means adding 1mL of your stock solution per 1 gallon of reservoir water nets you 4.36 PPM sodium hypoclorite in your reservoir. (16,500 / 3,785).
This concentration wont hurt your plants, but it should keep pythium at bay under normal conditions. Add every 3-4 days or whenever you change your water.
People get freaked out about using bleach, but it's a common practice in commercial hydroponics. At a reasonable dose, it's not going to infect your lungs and kill you from the inside like GMT suggests. Municipal water that comes out of your faucet is treated with chlorine. Chlorine's a micronutrient that plant use. Even hobby fertilizers like dynagro intentionally add it to their products. Going to take a leap of faith and say it's not putting you, your plants, or your loved ones in any immediate danger at the proper dose.
Last edited by clown baby; 09-04-2017 at 01:42 AM..