I work for a chemical company and have a degree in chemistry. I've tried a bunch of different things and I have had the best luck with UC Roots. Yes, you can get HTH pool shock (calcium hypochlorite) and you can use bleach (sodium hypochlorite). However, both of those products when added to water turn into Hypochlorous Acid.. which is the active ingredient in UC Roots. UC Roots claims to simply be a de-mineralizer / anti scale.. which is true.. but I honestly think that is just some wordsmithing to get away from calling itself a "sanitizer" or "biocide". When you do that, you need to register with the EPA, create a label, conduct studies, etc. I found UC Roots to be very forgiving and it is already the active form of Hypochlorous acid. Yes, it is a lot more expensive than HTH; however if you buy a lb of HTH and accidentally get it wet.. it will ignite and cause a chemical fire releasing chlorine gas fumes and burn your house down. I have a small personal grow, 4 pot rDWC system.. and a $12.99 jug of UC roots last me my entire Grow. Not a big deal for the convenience.
My first grow I was using the Flora Nova line of nutrients and decided to complicate things and added some Floralicious. Big mistake.. within a few days my rootes were brown with nasty shit growing on them. I did a res change and added UC Roots at half the dose and within a few days my roots were perfect again. They did still have some staining but my understanding is that is from the Flora Nova Bloom.. super stainy.
You can certainly use 34% H202 as well.. it just doesnt last as long in the RES as UC ROOTS because it is so reactive and if you get 1 drop in your eye your eye will turn white forever and you will be blinded. UC Roots doesn't have that same danger. As a side note.. I have some weird EYE issues my doctor says is caused by wearing these fucking masks all day long and he told me to use AVENOVA Eyelid spray. Well guess whats in it? A 0.03% Hypochlorous acid solution. Yes it is super dilute but you can spray that shit right on your eye and it doesnt cause any issues.. it just breaks apart the gunk on your eyelid that can cause infections. TMI I know.. but i thought it was cool that I was prescribed the same shit im using on my garden.
UC Roots at half the dose recommended and keep it simple. Just use a 1-2 part Hydroponic approved nutrient line and NOTHING else except maybe some silica to help keep those stalks strong because the net pots do not provide the same stability as a large pot full of soil.. unless you build a trelis system (which I do anyways) because I like to grow 5-6' trees.
Below is a pic of my roots after i added Floralicious... after adding UC roots all the brown was gone within a few days and the plants were loving life.
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