DWC Issues

[Erryl.Flynn]

Hi all,

I am new to these forums and created an account to specifically address an issue that I have been facing with DWC.

In veg, I observed a gradual increase in pH that was not drastic and seemed to be ideal for the absorption of nutrients (i.e., 0.01 increase maybe every other day). This tells me that the plants are sufficiently absorbing the nutrients provided, and thus, they are not concentrating in the reservoir.

Recently, I switched to flower and have noticed HUGE pH drops (i.e., 0.5+ everyday). I am constantly trying to bring the pH back up but it is an ongoing battle. I have been using max of 3/4 strength nutrients in order to prevent lock-out. The plants are vigorous and healthy, but the pH swings are worrying me and are becoming a nuisance.

I'm using H&G Aqua Flakes A+B and some Cal-Mag by Botanicare. I am considering picking up some Floraklean or Clearex just to purge the roots of any excess salts that may be hindering absorption of fresh nutrients. I've read this is not necessary with DWC, but I am willing to give it a shot.

The roots are white and healthy, so I do not attribute this to a root infection and the temp of the res remains between 63-68 F at all times.

If anybody has any recommendations/advice on this matter it would be much appreciated.

Bless,

Erryl Flynn

 

[Erryl.Flynn]

Pics

Pics

Here are some pictures of (I) the root zone and (II) the foliage. Note, that is not the reservoir that the plants grow in. It is merely the change-out ressie.

I picked up some FF Sledgehammer and gave my girls a bath. Only time will tell, but so far (i.e., the last 12 hours), the pH has remained stable. Fingers-crossed.

 

[WelderDan]

DWC is a pretty forgiving medium. Your PH is going to swing, and that's actually a good thing. Different nutrients are more available at different PH levels, and the swing allows the plant access to a wider range of nutrients.

You will never get it stay at a set number, and you will go crazy if you try. I know, I tried.

I eventually ditched the PH meter and quit worrying about it once I learned to read the plant

 

[mojave green]

Looks good

 

[LostTribe]

with bubbling the dwc water your ph ought to be rising? Normally would need to drop ph daily. Plant looks fine. Are your roots brown? Smell bad? If so sm90 is your friend but not a miracle worker. I won't do any dwc other than veg. Hydro for 12 plus years.

 

[HarvestMoon303]

That plant is beautiful.

I decided to try a few plants in DWC this run, and after filling the buckets, I have topped off with some 1/2 strength nute solution a few times in 9 weeks. I measured the pH once, ever. Roots are beautiful, and I let the rez get nice and low before I fill it back up. I just flipped to flower, but I don't plan on checking the pH in flower either, unless I start to see problems.

She doesn't look as nice as yours, but I had just cut 12 clones off of her (last female plant with those $ genetics). Roughly week 7, and the stem is the diameter of a US quarter.

Here are some pictures of (I) the root zone and (II) the foliage. Note, that is not the reservoir that the plants grow in. It is merely the change-out ressie.

I picked up some FF Sledgehammer and gave my girls a bath. Only time will tell, but so far (i.e., the last 12 hours), the pH has remained stable. Fingers-crossed.

 

[Erryl.Flynn]

with bubbling the dwc water your ph ought to be rising? Normally would need to drop ph daily. Plant looks fine. Are your roots brown? Smell bad? If so sm90 is your friend but not a miracle worker. I won't do any dwc other than veg. Hydro for 12 plus years.

That's what I thought it was supposed to do... In veg, the pH gradually increases. However, with both of the plants that I have in flower - the pH has been dropping. This starts happening after about ~2 weeks into flower.

I have been topping off with bubbled tap water (pH = 7.9) mixed with ProTekt to bring it back up. I'm not sure if the plants are excreting certain acidic metabolites once it senses to go to flower, or if the water:nutrient ratio is increasing, and thus, the nutrients are concentrating in the res. I check my EC with every feed and never let it go above 1.4-1.6.

No smell, slime, or anything of that nature. The root mass is MASSIVE. I use Hydroguard with every res swap. Additionally, I just purchased some Orca and plan on making a microbe tea with Ancient Forest, Orca, Hydroguard, and some molasses tomorrow and adding that to the res just to ensure that the roots are as healthy as possible.

What is the reason you only used DWC for veg?

 

[Erryl.Flynn]

DWC is a pretty forgiving medium. Your PH is going to swing, and that's actually a good thing. Different nutrients are more available at different PH levels, and the swing allows the plant access to a wider range of nutrients.

You will never get it stay at a set number, and you will go crazy if you try. I know, I tried.

I eventually ditched the PH meter and quit worrying about it once I learned to read the plant

Yeah I definitely was riding the "pH rollercoaster" for the initial part of the growth but been letting it drift for the exact reason you just mentioned. It's just strange because the pH was rising during the veg phase, which is what I thought was supposed to occur throughout the entire duration of the growth. However, it is dropping pretty quickly in flower (it went from 5.9 to 5.4 in the last 12 hours). It is becoming a nuisance.

Have you ever experienced the pH dropping in your system?

 

[Erryl.Flynn]

That plant is beautiful.

I decided to try a few plants in DWC this run, and after filling the buckets, I have topped off with some 1/2 strength nute solution a few times in 9 weeks. I measured the pH once, ever. Roots are beautiful, and I let the rez get nice and low before I fill it back up. I just flipped to flower, but I don't plan on checking the pH in flower either, unless I start to see problems.

She doesn't look as nice as yours, but I had just cut 12 clones off of her (last female plant with those $ genetics). Roughly week 7, and the stem is the diameter of a US quarter.

View Image

Thanks! I'm trying not to worry about the pH too much and like to let it drift between pH = 5.3 - 6.5, but the pH has been dropping pH < 5.3 and I can see ill effects - the leafs become deformed and are contorted. When I keep the pH in that range, this problem goes away. I'm envious that you can go without monitoring the pH and not have any issues!

 

[mojave green]

I think that happened to me once. Think I was underfeeding if I recall correctly.

 

[Erryl.Flynn]

I think that happened to me once. Think I was underfeeding if I recall correctly.

Really? I've been feeding way under the prescribed amount. Doesn't it seem like the pH would go up, though, if the plants were underfed (i.e., they would take up the nutrients faster than water)?

Perhaps I should try bumping up the nutes...

 

[Erryl.Flynn]

I think that happened to me once. Think I was underfeeding if I recall correctly.

I'm actually pretty significantly underfeeding at the moment. I was thinking that the plant's were utilizing more water than nutrients, and thus the pH was dropping as the nutrients were concentrating at the bottom of the res. Hence, why I have been underfeeding. EC is at about 1.2 right now. Doesn't it seem like underfeeding would cause the pH to rise instead of drop? I'm definitely willing to increase their feed schedule though if you think it might help.

 

[Erryl.Flynn]

My apologies for the double post. Didn't see that this had expanded to a second page and thought my post was lost in the cyberwebs.

 

[Jimbot23]

I just finished my first DWC grow and was having the same problem but from mid-late flower. Pretty sure it was overfeeding for me. Have you checked your ppms/ec? When ppms rise, ph usually drops. .5 each day isnt too crazy. I was getting up to a full point per day.

You mentioned you were going to start brewing tea? I did the same right around switching to flower (was getting slime) and it seemed to supercharge my grow. My ppms had to drop a lot after adding tea and overall health improved drastically.

Everytime I started getting big ph drops I just changed the res and lowered ppms until the problem stopped.

 

[Erryl.Flynn]

I just finished my first DWC grow and was having the same problem but from mid-late flower. Pretty sure it was overfeeding for me. Have you checked your ppms/ec? When ppms rise, ph usually drops. .5 each day isnt too crazy. I was getting up to a full point per day.

You mentioned you were going to start brewing tea? I did the same right around switching to flower (was getting slime) and it seemed to supercharge my grow. My ppms had to drop a lot after adding tea and overall health improved drastically.

Everytime I started getting big ph drops I just changed the res and lowered ppms until the problem stopped.

Hey Jimbot23, the issue definitely arises right in the mid-late flower stage. I wish I knew more about plant physiology to determine what exactly is happening, metabolically, at this stage. Perhaps, the plant's hormone regulation is altered, and thus, it produces acidic metabolites which end up in the res, require more water than nutrients, etc.

I check my PPMs and never set it above an EC of 1.4. It seems like although my pH is dropping, the EC isn't going up significantly. However, I am using a Truncheon EC meter and it doesn't give specific values - just a range. So it is possible that the EC is indeed increasing and I'm just not able to capture it with my instrument. I dropped by nutrient intake to 50% of the recommended dosage in conjunction with using Sledgehammer to flush between res changes and it seems to be abating the pH drop slightly, although it is still occurring.

I'm in the process of brewing my first tea right now (Ancient Forest, Orca, Hydroguard, humic acid, Mycogrow, and blackstrap molasses) and am going to apply it tonight. Hopefully this will correct the issue. Although the roots do not have any visible slime and appear to be in great health - it seems like the only other explanation for what is happening considering bacteria consume carbohydrates and excrete acid.

How did your grow turn out in the end? Are you planning on sticking with DWC?

Thanks for your input,

~Erryl

 

[WelderDan]

Yeah I definitely was riding the "pH rollercoaster" for the initial part of the growth but been letting it drift for the exact reason you just mentioned. It's just strange because the pH was rising during the veg phase, which is what I thought was supposed to occur throughout the entire duration of the growth. However, it is dropping pretty quickly in flower (it went from 5.9 to 5.4 in the last 12 hours). It is becoming a nuisance.

Have you ever experienced the pH dropping in your system?

I always saw a drop when I added nutes. Never noticed a rise like you describe.

What you didn't say (or maybe I missed) was if you switched to a flowering nutrient. I'm assuming you did, and the upswing started after the switch to flowering nutes.

Like I said, I ditched the meter and quit worrying about it. I knew it was going to swing, and just rolled with it.

I also let the rez go almost empty, then would top it off (water straight from the tap) and added nutes at low strength. Then I'd add a little more nutes a day or so later. I watched how the plants reacted, adding a little more every few days, and when the leaves started to reach up (I call it peaking, others call it praying) I knew I hit the sweet spot.

 

[Jimbot23]

Ended up turning out pretty good. Got over 500g from a 1000W. I've only grown a few times and it was like 10 years ago so I'm pretty damn happy right now.

Seriously considering switching to coco though. I've gotten things dialed in pretty well, but I don't like that there is so much to possibly go wrong. It's a hard choice since I'm invested in it and once I got it dialed the growth was insane.

I'm using almost the exact same brew as you, just no humic acid. I'd like to understand all the biology and chemistry better, but for now just go with what works for other people. The tea really seemed to stabilize everything and act as somewhat of a buffer to the plants, allowing for a larger margin for error. My res smelled like a dirty fish tank, but after the tea it always smelled like healthy soil.

 

[Erryl.Flynn]

Root Exudates

Root Exudates

So I've been doing a bit of research in regards to plant physiology/metabolism and have discovered that plant roots release a broad variety of chemical compounds to attract and select microorganisms in the rhizosphere - compounds known as root exudates. These exudates consist of organic acids, phenols, plant growth regulators, phenols, flavonoids, sesquiterpenoids, and the list goes on.

These compounds all have very specific functions. For example, organic acids act as intermediates in carbon metabolism, are key components in a multitude of mechanisms that plants use to cope with nutrient deficiencies, metal (in)tolerance, and plant-microbe interactions operating at the root-soil interphase.

Intuitively, because a large number of these compounds are acidic, they are consequently going to lower the pH of the water because there is no microbial buffer. In soil, there is going to be a healthy and consistent microbiota that is able to both sequester and metabolize these exudates, which translates to improved root health, and ultimately - to overall plant health.

Thus, I am thinking that amending the root zone and reservoir with beneficial microbes that they will be able to metabolize these exudates as they were meant to be metabolized, and hopefully, stabilize the pH in the process. I'm 24 H. into my brew that consists of Ancient Forest, Orca, Hydroguard, humic acid, Mycogrow, and unsulphured blackstrap molasses. I inoculated the root zone with some of the 24 H. brew and am going to repeat the process at 48 H.. It is important to catch the microbes in log phase so they have the greatest ability to inhabit your roots/res. Ergo, I'm going with two time-dependent treatments.

I'll be sure to update after the microbes have some time to colonize.

~Erryl

 

[Jimbot23]

Good stuff man. Be careful using the tea early. You want the molasses used up before you add it so you don't feed any bad bacteria that might be lurking around (or so I've read). I never had an issue but always waited 48 hours.

 

[potty1]

You had it right in a previous post.
Back the nutes off to 1ec and they'll be more stable.
They're taking more water than nutes hence the solution left becomes more acidic.
Don't start fucking about with microbes and teas and shit.it only leads to headaches.
Keep it simple