the only thing i know for sure you can't use with chlorine is fulvic acid. when mixed, it turns into a really nasty gas. thanks to
@Yesdog for pointing that out to me and verified by BioAG maker of my fulvic acid.
I'd much prefer hydrogen peroxide to chlorine products to help with hydro. I used 35% food grade peroxide at 0.5ml/L twice a week for years without ever having root rot in DWC where I sometimes went the whole grow without a nute change in my tubs. I tend to do one complete change right after the stretch now with good results tho not noticeably better than no nute change at all.
Checked out that Pythoff and they don't say on the
Label what is in it. They do say it's not compatible with peroxide or beneficial bacteria so it's likely some nasty chemical I wouldn't want in my plants anyway.
I'll stick with peroxide as it's the safest thing to use and you can drink small amounts for your health unlike bleach. H2O2 -> H2O + O+.
As peroxide will also break down things like amino acids in quality hydro nutes you should add it 24 hours before adding any fresh nutes to your mix.
Yar. Yea further reading and a little more remembered-chemistry later it makes more sense. Basically any organic (carbon-based) substance is effected by any heavy oxidizer. In the case of humics+chlorine it turns into its own special little surprise.
So amino acids, sugars, organic acids (humics and to a lesser extent even citrates/acetates), bacteria, etc.- oxidizers should help break most of them down. I honestly don't know what happens after that step tho. Organic chemistry is where I stopped in college lol but it's also a science in its own to predict what reactions happen next. It's easier with non-organic ions, but organic elements are capable of doing lots of things... like life.
Oxidizers/reducers (chlorine and peroxide are both oxidizers) in general basically like to make ions change shape ('species'). The more complicated the shape, the more things it can turn into. Only the most stable species survive, like general salt ions. Organics happen to be specifically vulnerable to this. The only thing that prevents the roots from being affected is the hard cell wall (looking at you, silicon and calcium). So keep your tugor pressure up and cal/mag/maybe-si and you'll be fine.
As far as the root-rot with RO- honestly if your roots only touch RO water with a mixed nutrient solution (not plain!) there's no difference. RO water just has less cal, mag and carbonates (and other stuff, but not relevant really. Chlorine is the biggest factor, but everything else are minerals safe for human/plant consumption). Carbonates provide the buffering.
This #1) DWC specifically. RO water or any water with limited buffering capacity is more prone to local pH changes from root exudates. The same way you can more easily swing ph with Up or Down with RO, the roots can do the same thing with the organic acids they produce. So the immediate root zone might be able to reach a lower pH than normal which generally benefits microbes (most prefer lower pH in solution), and you may never see this ph change/reaction in the bulk of the solution because it is so local and meant to neutralize quickly. The root exudates are also generally organic acids, which can serve as food for microbes. Anyways, you can protect against this with a larger rez and more water movement. Probably 3+ gallons per plant
#2) Chlorine *may* leach organics from weak roots. Basically under an oxidizer, sick roots may decompose into soluble organics a bit faster. I really don't have any theories on what that means tho... but possible that some pathogen happens to like the decomposed organic more? From what I read tho, it's generally just best to keep the same amount of free chlorine in your system as possible. Lets the roots adjust. So if you're doing organic- always condition. If sterile- always chlorine. Temporary chlorine or peroxide will probably make things worse.
#3) Flushing with RO/DI only or any 'hypotonic' solution. This can basically make your roots 'burst' over time because the water wants very badly to leach ions from the plant tissue. But it's also realllly hard on any biolife. So the weakened roots might offer opportunities for pathogens after a flush, when the nutes are back.
#4) Introducing chlorine or oxidizers when not normally present is usually bad news. Think about it... you have a non-organic rez, and a bunch of microbes moved in. You killed them by exploding their cell membranes. You now have an organic rez. This also introduces a new array of food that may lead to a bloom of... god knows what. Algae is also notorious for vacuuming then dumping nitrogen and phosphates when it dies. All oxidizers also get consumed based on the amount of... consumables. So if you have a really bad infection, the "normal amount" of oxidizers might get consumed very quickly (an ORP pen/sensor can detect this, but i think they're pricy).
#5) Tea is honestly risky. If any one thing goes wrong, you're just dumping organics into your rez. Absolutely dechlorinated water, must foam (CO2) and then stop, and you have to make sure the sugars are gone. I think I might start just breeding single species in agar now...
#6) A weak oxidizer (like tap chlorine PPM) might make things worse. Chlorine sensitivity in microbes is a very large spectrum. A weak amount kills something... but maybe it was the only organism keeping things in check. So with tap water, its good to dechlorinate if you're not running sterile.
TL;DR; probably not the water. Could be contamination somewhere, but it doesnt matter. Your rez will attract biolife one way or the other, the only safe rez is one thats hard to live in. This can be done with oxidizers or competitive biolife. If you still have issues, you probably have weak roots/plant. Any kind of stress may lead to root die-off. A lack of turgor-pressure/calcium/silicate can also lead to weak roots.
Beneficial fungus is also great at protecting the roots- but its a bitch to deal with in DWC. It can shield the roots from pathogens and 'buffer' the root ph by eating the organic acid exudates (in exchange for phosphates usually). I read that Mychs can even shield roots from pH between 4 and 8 (provides an optimal internal pH). The only way I've read to get a good Mych colony in DWC is have a porous medium around the root base that is generally moist.
I need to stop writing such long posts....
.