Rdwc huge ph fluctuations

TheImp

Member
Hey everyone, first post here. Looking for some insight. This is my 4th hydroponic grow, up until now all have been dwc.
Setup:
3 reservoirs- 2 in tent 1 external
Alita 40 air pump, 2 stones per res
General hydroponics nutes
Using ro water
Maxisun led lights
Recirculating pump guesstimate at 20 gallons an hour
Total water volume is 30 gallons
Feeding regimen:
All nutes added at 2/3 strength
Mix armor si for one hour with pump and air stone
Add calmag mix 5 min
Add trio, micro, gro, bloom
Add diamond nectar
Add floralicious
Let mix another 5-10 min
Ok, I think I covered most of my process, if I missed something let me know.
a couple weeks back, we’ll maybe 3 weeks now I noticed my feed lines into both reservoirs where just trickling, I pulled a plant to peek inside the res and saw that brown slime. Now this being my 4th go at this I already knew the importance of light proofing but somehow overlooked this crucial detail during my initial setup. It was extra stupid of me since I dealt with this same issue on my first dwc grow. So after kicking myself a few times I pulled the plants, cleaned the three reservoirs, cleaned the roots as much as I could and put everything back, also swapped out all hoses. Now I’ve always run beneficial bacteria and enzymes so I maxed out the enzymes and did 1.5 strength on the southern ag. I thought I would be in the clear and continued with my lst and net. So I was good for a week and a half or so but then one morning I’m doing my rounds checking ph and ppm and noticed that my ph was plummeting, from 6.1 to 4.7 over night, literally 14 hours. So fuck, I panic and dump the water mix up another 30 gallons and refill. This time I adjusted the ph to 6.5, I know it’s high but I was trying to account for the swing while staying within the guidelines.
Next day 4 point fucking 7 again. Mind you it takes almost a full day to produce 30 gallons of ro for me. So I noticed this time that my holding can for ro has a slime coat everywhere, even though I was running southern ag and hygrozyme. So I drain it, dump a cup of bleach and ton of water and scrub. Rinse scrub rinse and refill.
another res change , ph’d to 6.4 and the next day I kid you not 4.7
So I’m kinda at my wits end here. And today I said fuck it and added 15ml of 7% bleach to the res and let it circulate for a couple of hours, you can see in the pic how pissed off the plants were.
so after that ran and my plants looked like death warmed over, I drained and ran tap water through for another hour to kinda rinse everything out. Then refilled with new water again minus the bb and enzymes. Ph 6.4 ppm 550 Also ordered a uv sterilizer.
I’ve backed off the lights so they can recuperate a bit , some pics below, they are already bouncing back from the bleach, time stamp bottom right.
question 1 -
if I switch to a sterile system will it stop this scourge of slime/ bacteria/ algae
Question 2-
Will I need to run anything like pool shock in conjunction with the uv light?
Any thoughts ? I don’t want to scrap this grow!
thanks for taking the time to read through!
 

Attachments

myke

Well-Known Member
I think you've done everything right,did some bleach make it through your net pot?
 

Wastei

Well-Known Member
Floralicious Plus has no place in DWC. Decaying organic matter with sugars = bad bacteria cultures. Bacillus subtilus do absolutely nothing in water cultures and free floating sugars is a recipe for disaster.

Don't buy into the marketing and dial in the mineral plant food feeding strength food+silicate, nothing else is needed. Oxidizers help to keep thing clean and pristine and combats parasitic oomycetes like pythium. Hope that helps.
 
Last edited:

rkymtnman

Well-Known Member
Ok will do, next time I do a change out I’ll skip em. Any thoughts on switching to sterile and running uv? Will it end this issue or am I up a creek?
i've run both ways: hth pool shock for sterile or southern ag fungicide for good bacteria. both work, both are pretty cheap.
 

TheImp

Member
Floralicious Plus has no place in DWC. Decaying organic matter with sugars = bad bacteria cultures. Bacillus subtilus do absolutely nothing in water cultures and free floating sugars is a recipe for disaster.

Don't buy into the marketing and dial in the mineral plant food feeding strength food+silicate, nothing else is needed. Oxidizers help to keep thing clean and pristine and combats parasitic oomycetes like pythium. Hope that helps.
Ok I’ll ditch the extras. Sounds like I’m the one who’s been feeding this problem. ‍♂
You think if I ditch the extras and continue beneficial bacteria and enzymes it’ll fix the issue? Also wondering how the uv wouldn’t work based on the nutrients used? Wouldn’t it kill any free radicals regardless of the food? If I have to switch up my nutrients so that I can run Uv and not have to worry about adding bb and enzymes or pool shock and h2o2 I’d be on board.
 

smokey0418

Well-Known Member
Had some root issues ph was all over. Bio clean fixed it up in a week . Finally stability. Don’t forget to inoculate the pot each week .
 

OrgrO

Well-Known Member
Any thoughts on switching to sterile and running uv?
UV is great for killing any pathogens in source water. I use RO water and run that through a UV filter to kill any bacteria, virus or algae that make it through the RO filter.
Using a UV filter to keep your nutrient solution sterile will cause certain elements to precipitate out of suspension.
 
Top