Can an Unhealthy Plant's Roots Cause Reservoir pH to Keep Spiking up?

The pH in one of my hydro reservoirs keeps shooting up to around 6.3 overnight. I have to use an entire cap of pH down to bring it down to 6.0 .
There are three plants sharing this hydro reservoir and two of them are showing signs of stress. The third one shows a slight nute deficiency but looks healthy overall, especially judging by its roots.

The Healthy looking plant's roots:

Other 2 plants showing signs of stress' roots:



At first I suspected my pH was drifting up so fast because my RO water was lacking mineral content to help buffer the pH. But I conducted some tests and my "control subject" RO water is stable at 5.8 over the course of weeks so I don't think it is my ro water causing the drift. I even made another reservoir full of fresh water pH'd to 5.8, let it sit for 24 hours, and the pH shot up to 6.3 the day after I introduced the plants to it.

At this point I'm inclined to believe the roots of the plants are the cause of the pH going up? The roots hang out of solo cups and run down into the hydro reservoir so they do come in contact with the water. Is it possible one or two of the plants have become sickly and are contributing to some type of bacterial growth in the water? Any other variables that may be contributing to high pH in hydro reservoir?

I am feeding Jack's hydro 5-12-26 and CalCinit at 800ppm (after mixing solution, i let sit for 24h before I pH up to 5.
Temperature around 80f and rH is at 60%

Here's a photo of the three plants that share the reservoir:

The tallest plant is the healthiest looking one and its roots look healthily white. Can't say the same for the other 2 plants so much.

What's your rez temp? If your room temp is 80°, eventually, without intervention, the rez will be the same (logically). 80°is perfect for root rot. This is why i changed to coco.

If you don't isolate your plant's rez's, all of them will get it. This is why I didn't go recirculating when I was DWC.

I was always chasing Ph in DWC. the plants will change the Ph as they eat if they're not drinking the same ratio of water, but with your brown roots and slime on that 3rd plant adding contaminates to the rez it will cause wild swings.
The damaged roots need removed ASAP!
Is the rez stagnant? I see no at air stones/ bubbles.
And are you using any microbes?

Deep Water Culture is a battle of nutrients to water, if the plant eats up certain nutrients it will inevitably raise the PH of the solution and result in alkalinity of the water. Are you running any form of Silica?

calvin.m16 said:

Deep Water Culture is a battle of nutrients to water, if the plant eats up certain nutrients it will inevitably raise the PH of the solution and result in alkalinity of the water. Are you running any form of Silica?

Click to expand...

I use agsil16h as silica up. I make a solution that is almost identical as Pro-Tekt. I have read a lot about this potassium silicate causing pH to drift up more. I've used it as pH up for awhile without any problems. I'm not convinced my problem is solely because of the silica i may be using though

Johiem said:

What's your rez temp? If your room temp is 80°, eventually, without intervention, the rez will be the same (logically). 80°is perfect for root rot. This is why i changed to coco.

If you don't isolate your plant's rez's, all of them will get it. This is why I didn't go recirculating when I was DWC.

I was always chasing Ph in DWC. the plants will change the Ph as they eat if they're not drinking the same ratio of water, but with your brown roots and slime on that 3rd plant adding contaminates to the rez it will cause wild swings.
The damaged roots need removed ASAP!
Is the rez stagnant? I see no at air stones/ bubbles.
And are you using any microbes?

Click to expand...

my room temp is around 83 tops, and my reservoir usually measures around 79.5 so yeah basically 80 degrees. I never had problems with root rot but I suspect I may have a minor onsetting case of it at the moment? My plants aren't dying at a rapid rate but they are looking slightly hungrier as the days go by. I do not use air stones or bubbles for this style of grow. Roots in the solo cups have plenty of oxygen and there is an air gap between the solo cups and the water table. If I do have root rot I suspect it may be due to temperatures in combination with environmental conditions (for example, my rH was stuck at 90%+ for a few days with these plants and I read that roots will stop drinking water and rot as a result, if rH is too high).I don't use microbes but just decided this past weekend to try going sterile with pool shock.

After I first posted this thread (4 days ago) I noticed my res water was getting very cloudy and pH was still going up. I started to suspect root rot based on your comments and much research (read some people saying things like cloudy water means dead organic matter in the water). I went out and bought some pool shock and made my own DIY solution of UC Roots. I put a heavy dose of pool shock into my reservoir (heavy dose on accident) but the plants didn't seem to be stressed by it. The next day i changed out the water completely and added a moderate dose of pool shock. It has been 48 hours since administering pool shock and changing the water out and my pH doesn't seem to be drifting up anymore and the res water is not cloudy anymore. Does this mean I probably got rid of a lot of the nasty root rot bacteria or whatever bacteria may be in my water?

My plants are still not perking up or looking too much better but the new growth does look slightly healthier than older growth. I read it may take some time for plants to bounce back from root rot conditions though.
Jack's Hydro 3-2-1 is around 900ppm (higher than what I usually do) and pH is at about 6.0

Here are some more recent photos that show how the plants in this reservoir are looking now:

experiencing slight tip burn in this 1st photo. Over fed???




Any idea if I'm absolutely experiencing Pythium? Or maybe a different pathogen caused pH swing which caused nutrient uptake problems which have led to the plants looking the way they do now?

I may have to ghetto-rig some reservoirs using 2 gallon buckets because i cant fit any more reservoirs in my veg room to quarantine these three plants from each other. That will be my next course of action if these plants don't liven up.

Those are the sickest plants I have seen on here in quite a while. I can't help with that Jack shit because I don't know jack shit. I usually don't try to discourage the Jack's crowd but you really should try Lucas Formula or Flora Nova to make your life so much easier. You should also start with simple 5 gal buckets and airstones. Growing weed is supposed to be simple. KISS

You're not putting concentrated pH liquid straight into the res are you because that can cause the nutrients to precipitate out of solution. I dilute 1:10 then dilute further before adding to res. If you're having problems with DWC, I suggest you try an SWC, info in my sig.

bring the ph down to 5.5 if its going up that fast. Does the EC change too?

During flower of my very first DWC grow, pH started spiking up with yellowing leaves. I battled to the end while trying to keep it under control and found bad root rot when I chopped, it was rotted in the middle of the roots so not obvious from the outside. The plant had also grown new some healthy roots on the outside to make up for the diseased ones in the middle, so amazingly I still got an ok harvest for a first try.

I had crappy bubble flow back then, have got a much better pump and stones now. I also use bleach to keep my rez sanitised, I run it a bit warm 22-24C for faster growth.

Looking through the pictures I can only make assumptions.

You show healthy roots but I don’t see pic of healthy plant , so that my first assumption.

If you have a lush green stress free plant at your 800 ppm assuming again your using 500 scale so 1.6ec ? Let’s see it because I think thats hot

The brown roots , that’s definitely some sort of rot. Rinsing roots by hand getting that crap off before you bleach , shock or h20 would be a better option as your probably just touching the surface.

Cleaning that up and regular doses should be able to stay on top .

Myself I started chilling and using Bacteria , eg orca or hydroguard to combat. Looks like what your doing is mostly working just need some tweaks.

Enjoy and good luck with the grow.

newguy41410 said:

The pH in one of my hydro reservoirs keeps shooting up to around 6.3 overnight. I have to use an entire cap of pH down to bring it down to 6.0 .
There are three plants sharing this hydro reservoir and two of them are showing signs of stress. The third one shows a slight nute deficiency but looks healthy overall, especially judging by its roots.

The Healthy looking plant's roots:
View attachment 5084279
Other 2 plants showing signs of stress' roots:
View attachment 5084278
View attachment 5084276

At first I suspected my pH was drifting up so fast because my RO water was lacking mineral content to help buffer the pH. But I conducted some tests and my "control subject" RO water is stable at 5.8 over the course of weeks so I don't think it is my ro water causing the drift. I even made another reservoir full of fresh water pH'd to 5.8, let it sit for 24 hours, and the pH shot up to 6.3 the day after I introduced the plants to it.

At this point I'm inclined to believe the roots of the plants are the cause of the pH going up? The roots hang out of solo cups and run down into the hydro reservoir so they do come in contact with the water. Is it possible one or two of the plants have become sickly and are contributing to some type of bacterial growth in the water? Any other variables that may be contributing to high pH in hydro reservoir?

I am feeding Jack's hydro 5-12-26 and CalCinit at 800ppm (after mixing solution, i let sit for 24h before I pH up to 5.
Temperature around 80f and rH is at 60%

Here's a photo of the three plants that share the reservoir:
View attachment 5084277
The tallest plant is the healthiest looking one and its roots look healthily white. Can't say the same for the other 2 plants so much.

Click to expand...

Run sterile res with oxidizer like bleach(sodium hypochlorite). You currently have pythium root rot. 3-5ppm is recommended for DWC, here the dilution calculator: Chlorine dilution calculator

70's natureboy said:

Those are the sickest plants I have seen on here in quite a while. I can't help with that Jack shit because I don't know jack shit. I usually don't try to discourage the Jack's crowd but you really should try Lucas Formula or Flora Nova to make your life so much easier. You should also start with simple 5 gal buckets and airstones. Growing weed is supposed to be simple. KISS

Click to expand...

They contain the same stuff in different ratios? Why pay for water weight? I don't understand that. For sure there's a learning curve going from bottles to salt granules, but there's so many people who's done the same who can guide people in the right direction.

Jacks tap or RO formula is just as easy to use as Lucas formula or anything else. Keeping the solution stable is something every grower need to learn and understand growing in hydro. There's so many ways around that.

smokey0418 said:

Looking through the pictures I can only make assumptions.

You show healthy roots but I don’t see pic of healthy plant , so that my first assumption.

If you have a lush green stress free plant at your 800 ppm assuming again your using 500 scale so 1.6ec ? Let’s see it because I think thats hot

The brown roots , that’s definitely some sort of rot. Rinsing roots by hand getting that crap off before you bleach , shock or h20 would be a better option as your probably just touching the surface.

Cleaning that up and regular doses should be able to stay on top .

Myself I started chilling and using Bacteria , eg orca or hydroguard to combat. Looks like what your doing is mostly working just need some tweaks.

Enjoy and good luck with the grow.

Click to expand...

Thank you for following along and actually reading my update as it shows! I really appreciate your post because you address some of my main concerns and seem to confirm my suspicions/bias.

First of all, I have never ran the PPM as high as I am right now for this res and am wondering if I should definitely dial it back? In the past I would consider 650-ish PPM as a full strength solution (0.5 scale, 1.2 EC). But as far as this specific style cloner goes I usually start a seedling or clone at 300 PPM (my cloner can propgate both seeds and clones btw). I have been using this cloner style for four years now and this is the first time I'm experiencing symptoms like this. I just came back from a five-month hiatus from growing because I foolishly brought home russet mites and reset everything. And to be honest I really can't remember if I was even feeding 600 PPM in the cloners before. I usually feed 650 in flower for sure but that is in a different room and a different hydro system (PPK hydro)

Here are some photos of one of my first grows four years ago with this style cloner:


So the photos above were from four years ago. Now that I am looking at those photos I realize I had the light much further away from the plants than i do now. I wonder if my light intensity is way too high? Lighting is currently at 500 umol at my tallest plant's tops using COB LED lighting.

Anyway, below are some photos I took this morning. You'll notice that the reservoir in the foreground is full of seedlings that are healthy. PPM is at about 200 in that reservoir. The reservoir in the middle is around 300-ish PPM and it's starting to have slight deficiencies like the worst reservoir in the back. I am confused why these two reservoirs are responding the way they are. One thing all plants in both those reservoirs have in common is that they came from seeds from the same breeder, Bodhi. But I highly doubt the seeds or genetics have something to do with it as Bodhi is a highly reputable breeder. So I really am scratching my head with these two reservoirs.



I just separated all three plants in the back reservoir into individual buckets so that they are quarantined to their own res. Hoping to pinpoint the problem by doing so. The PPM is pretty high in the buckets around 800ish PPM also. The only reason I am feeding 800PM is because I was wondering if they were just hungry because I brought my LEDs closer to them and turned the intensity up. But I am starting to think it's something having to do with bacterial growth, likely Pythium, in the water. Should I dial back to 600ppm for the plants in the back you think?

Edit: When I change out the water to my reservoirs I essentially rotate the totes. Maybe I am not disinfecting the totes between water changes enough? (I wash them in the shower with dish soap, should I start using bleach on them between water changes maybe?

newguy41410 said:

Thank you for following along and actually reading my update as it shows! I really appreciate your post because you address some of my main concerns and seem to confirm my suspicions/bias.

First of all, I have never ran the PPM as high as I am right now for this res and am wondering if I should definitely dial it back? In the past I would consider 650-ish PPM as a full strength solution (0.5 scale, 1.2 EC). But as far as this specific style cloner goes I usually start a seedling or clone at 300 PPM (my cloner can propgate both seeds and clones btw). I have been using this cloner style for four years now and this is the first time I'm experiencing symptoms like this. I just came back from a five-month hiatus from growing because I foolishly brought home russet mites and reset everything. And to be honest I really can't remember if I was even feeding 600 PPM in the cloners before. I usually feed 650 in flower for sure but that is in a different room and a different hydro setup (PPK hydro)

Here are some photos of some of my first grows four years ago with this style cloner:
View attachment 5086974View attachment 5086976View attachment 5086977
View attachment 5086975
So the photos above were from four years ago. Now that I am looking at those photos I realize I had the light much further away from the plants than i do now. I wonder if my light intensity is way too high? Lighting is currently at 500 umol at my tallest plant's tops using COB LED lighting.

Anyway, below are some photos I took this morning. You'll notice that the reservoir in the foreground is full of seedlings that are healthy. PPM is at about 200 in that reservoir. The reservoir in the middle is around 300-ish PPM and it's starting to have slight deficiencies like the worst reservoir in the back. I am confused why these two reservoirs are responding the way they are. One thing all plants in both those reservoirs have in common is that they came from seeds from the same breeder, Bodhi. But I highly doubt the seeds or genetics have something to do with it as Bodhi is a highly reputable breeder. So I really am scratching my head with these two reservoirs.

View attachment 5086978View attachment 5086979View attachment 5086980View attachment 5086981

I just separated all three plants in the back reservoir into individual buckets so that they are quarantined to their own res. Hoping to pinpoint the problem by doing so. The PPM is pretty high in the buckets around 800ish PPM also. The only reason I am feeding 800PM is because I was wondering if they were just hungry because I brought my LEDs closer to them and turned the intensity up. But I am starting to think it's something having to do with bacterial growth, likely Pythium, in the water. Should I dial back to 600ppm for the plants in the back you think?

Click to expand...

Not likely, you have pythium root rot. You need to have a strategy to keeping the solution clean and sterile. Either by oxidizers or Southern AG garden friendly fungicide containing bacillus amyloliquefaciens.

If you don't stay ahead of the problem it will persist and worsen. None of plants in your pictures have a well developed root systems or growth. You've had the same problem since the get go.

newguy41410 said:

Thank you for following along and actually reading my update as it shows! I really appreciate your post because you address some of my main concerns and seem to confirm my suspicions/bias.

First of all, I have never ran the PPM as high as I have run it now. In the past I would consider 650-ish PPM as a full strength solution. But as far as this specific style cloner goes I usually start a seedling or clone at 300 PPM (my cloner can propgate both seeds and clones btw). I have been using this cloner style for four years now and this is the first time I'm experiencing symptoms like this.

Here are some photos of some of my first grows four years ago with this style cloner:
View attachment 5086974View attachment 5086976View attachment 5086977
View attachment 5086975
So the photos above were from four years ago. Now that I am looking at those photos I realize I had the light much further away from the plants than i do now. I wonder if my light intensity is way too high. It is currently at 500 umol using COB LED lighting.

Anyway here are photos I took this morning. You'll notice that the reservoir in the foreground is full of seedlings that are healthy. PPM is at about 200 in that reservoir. The reservoir in the middle is around 300-ish PPM and it's starting to have slight deficiencies like the worst reservoir in the back. I am confused why these two reservoirs are responding the way they are. One thing all plants in both those reservoirs have in common is that they came from seeds from the same breeder, Bodhi. But I highly doubt the seeds or genetics have something to do with it as Bodhi is a highly reputable breeder. So I really am scratching my head with these two reservoirs.

View attachment 5086978View attachment 5086979View attachment 5086980View attachment 5086981

I just separated all three plants in the back reservoir into individual buckets so that they are quarantined to their own res. Hoping to pinpoint the problem by doing so. The PPM is pretty high in the buckets around 800ish PPM also. The only reason I am feeding 800PM is because I was wondering if they were just hungry because I brought my LEDs closer to them and turned the intensity up. But I am starting to think it's something having to do with bacterial growth, likely Pythium, in the water. Should I dial back to 600 for the plants in the back you think? I had taken a five-month hiatus from growing because I foolishly brought home russet mites and reset everything. And to be honest I really can't remember if I was even feeding 600 PPM in the cloners. I usually feed 650 in flower for sure but that is in a different room and a different hydro setup (PPK hydro)

Click to expand...

As others have stated about running sterile and the level you should be maintaining to keep a clean root system.
That’s great

i am going to base the next info off all plants being the same model as to say they all eat the same.

Personally have found in veg plants take very little nutes and light , charts say 300-500 ppfd and really they seem tobthrive for me with very little.
The nutes also , for example I use ro water and have a full does of calmag 3-4 ml per gallon and then just 150-200 ppm of grow for a total of 380 . My ppm goes down 10 in a few days .


What you need to find is the level were your ppm stays the same and when you do I’m sure you will find the ph doing the same and the water just goes down and everyone is happy.
If you ppm goes up it’s too high and if it’s dropping fast too low .
i fought for some time getting this down but definitely in a much better place now that I do.

I hope this helps .

Wastei said:

Not likely, you have pythium root rot. You need to have a strategy to keeping the solution clean and sterile. Either by oxidizers or Southern AG garden friendly fungicide containing bacillus amyloliquefaciens.

If you don't stay ahead of the problem it will persist and worsen. None of plants in your pictures have a well developed root systems or growth. You've had the same problem since the get go.

Click to expand...

I started using 1ml of pool shock every couple days over the weekend. pH isn't rising anymore and water isn't cloudy at all anymore. So those are good signs so far right? You aren't possibly referring to the plants in the first four photos from four years ago when you say none of my plants have a well developed root system are you? The plants from four years ago didn't have root rot and came out fantastic from seed to finish! I do think two of my reservoirs might have a case of pythium though.

smokey0418 said:

As others have stated about running sterile and the level you should be maintaining to keep a clean root system.
That’s great

i am going to base the next info off all plants being the same model as to say they all eat the same.

Personally have found in veg plants take very little nutes and light , charts say 300-500 ppfd and really they seem tobthrive for me with very little.
The nutes also , for example I use ro water and have a full does of calmag 3-4 ml per gallon and then just 150-200 ppm of grow for a total of 380 . My ppm goes down 10 in a few days .


What you need to find is the level were your ppm stays the same and when you do I’m sure you will find the ph doing the same and the water just goes down and everyone is happy.
If you ppm goes up it’s too high and if it’s dropping fast too low .
i fought for some time getting this down but definitely in a much better place now that I do.

I hope this helps .

Click to expand...

ahhh I see what you're saying as far as finding the PPM level that stays the same. Because if PPM goes down and ph Up that means plant wants more nutes and vice versa, correct? So try to find that balance. As far as your nute solution goes you're basically doing 200 ppm of your base nute and 180 of calmag? Am I interpreting that correctly? Thanks for chiming in!

newguy41410 said:

I started using 1ml of pool shock every couple days over the weekend. pH isn't rising anymore and water isn't cloudy at all anymore. So those are good signs so far right? You aren't possibly referring to the plants in the first four photos from four years ago when you say none of my plants have a well developed root system are you? The plants from four years ago didn't have root rot and came out fantastic from seed to finish. I do think two of my reservoirs might have a case of pythium though.

Click to expand...

Definitely the brown one is bad, personally would rinse it off the best you can then put it in your sterile system.

smokey0418 said:

Definitely the brown one is bad, personally would rinse it off the best you can then put it in your sterile system.

Click to expand...

I just separated the three plants into their own bucket reservoirs. I will try to pull the dead, darker roots out tomorrow. I think I'm also going to dilute the nutrient solution down to 400 PPM tomorrow. I don't think raising the nute strength helped with anything so I might just dial it back down to prevent further problems

newguy41410 said:

ahhh I see what you're saying as far as finding the PPM level that stays the same. Because if PPM goes down and ph Up that means plant wants more nutes and vice versa, correct? So try to find that balance. As far as your nute solution goes you're basically doing 200 ppm of your base nute and 180 of calmag? Am I interpreting that correctly? Thanks for chiming in!

Click to expand...

Exactly, nutes get used and my ph goes up.

We are looking for a perfect balance. Were very little changes.

yes, 180ppm of calmag and the rest is two part grow mixed at the rate of bottle but only 200 of it.

exactly