Follow up on my first sterile RDWC with ORP Control

Doing RDWC for a couple of years now, always using tea and last 4-5 grows always got a nasty root rot mid flower and lost most of my crop.
So I decided to go with sterile, using pool shock and ORP controller (ORP basically says, mow much free chlorine you have in your solution).
My findings so far:
- It works, mid flower now, all looks fine (except som K def)
- Some people say, 1ppm wont hurt your plants...NOPE, 1ppm constantly will kill them, that is around 750mV at ph6, which killed all my seedlings in a day.
-So far it seems, that good ORP level is around 420mV (less than 0,1ppm) runing constantly
- everything above 500mV resulted in stunted growth


Dosing basically looks like this:
I have a 20l tank with pool shock solution and orp controllers, that open washing machine valves, when Orp level falls below preset value.

Just a question, if somebody can help me: I developed misterious K deficency. Does anybody knows, if it can be related to Chlorine somehow? If not, must be VPD, as it is hot and AC lowers RH to 40% at 29-30C

Any questions, just ask...

Thank you!

Do your believe 420mV is capable of sterilization?

What are your water temps?

What pH values are occurring?

Any teasers about this orp controller?

Did you finish the grow root rot free? Im thinking of getting the apex controller and setting up the same thing. Why did you use washing mashing valves vs peristatic pumps? Also how did you convert mv to ppm?

Do you keep water at 68 degree's? Snype said .5 PPM for bleach. Do you make sure that light can not get at water? It will pass right through PVC and buckets that are not black. Do you use CO2?? If so the air pumps must be outside of the grow area, or you will be pumping CO2 into water, not oxygen.

I sorry for my late reply. Busy with work...
FOLLOW UP:
It works!
After many crops dead while using tea, I see the light!
Had a nice crop of AK47 and Jack herer. Good quality, no root rot, all fine! Thinking of quitting RDWC, but now I see it can be done.
Answers to your questions:

420mV IS capable of sterilisation. Occasional swing to 500+ is preffered, but everything above 600mV is harmful. For a very short burst it can be tolerated.
My water temp and everything is fine. Even had a month, that I went 23,24C, and survived.
PH values normal, 5,6-6PH. No big swings - If you have big swings, too little ORP/chlorine, shit is starting to grow!!! Letting ORP levels below 400mV will cause immediate slime on tubes! You need to keep ORP level as high as possible without harming plants. In my experience 420-450mV.

ORP Controller example:
http://www.ebay.com/itm/2in1-Digita...147462?hash=item2c87842d06:g:DJwAAOSwRLZUJPEi

Using washing machine valves because they are cheap! Peristaltic pumps are super expensive.

LocDog, all my technical aspects are/were perfected and overdone.
No Co2. My main tanks are outside the grow room. Some big ass air pumps, stones in each bucket and main res. But only this way (with ORP controller) i finished without root rot.

I think adding chlorine without ORP meter is pointless. You never know, what are your levels.

Any questions, let me know...

Would love to ask you a few questions about this if you have the time!

DS you mentioned at 500mv your seedlings died. Been dorking out reading some articles on greenhouse irrigation pathogen control and based off the research it seems 780mv exposure for 100% die off of Pythium spp. And rates even higher to control fungal or bacterial outbreaks.

Do you think it is possible that the die-off you experienced with the seedlings was because they weren’t well established?

I have a 6 site 8 gallon undercurrent with an approximate system volume of 50 gallons. Sterilization suggestions for greenhouse agriculture seem to indicate a target range of .5-2ppm.

Apparently MV readings are highly dependent on PH. A PH below 6.0 will cause chlorine off gassing (I can certainly smell it strongly at or above a ph of 6) but would like to target close to 6 because hydro.

50 gallons = 189271 mL

.5 ppm = .0005 mL/L

189271 (total volume) * .0005 = 94 mL

That seems like a ton of bleach. Especially considering most bleach is 9% chlorine

94 / .09 (pct chlorine in bleach)

= 1044 ml or 1 L bleach in its purchased form

Gut check I sick at math

94 mL * 189271 mL total system volume

= .00049 or .49 ppm


All of this seems crazy. Considering current culture recommends UC roots at 2-5ml per gallon of an ~20% solution hypochlorous acid (formed by bleach and water at lower PH 6’s)

Alright first post, some chemistry folks with basic math skills are probably going to tear me up. Oh well. Any input would be appreciated.

MTN

All of the calculations are based off an assumed ORP of 0mv which is not water fresh ro comes out at but I needed to keep the calculations simple. I have been slowly adding bleach drop by drop into the epicenter for the last few hours and monitoring orp values. And it will take a lot of bleach to maintain anything over 500mv it seems. Either way I will try to work up to 700mv at a PH of 6.1 and report back. The plants are definitely not looking good in the root zone. Oddly everything up top looks decent but not great. I have been fighting this (whatever it is for a while) trying to get it under control before I flip.

Did you stick with rdwc, any updates to your setup?