Deficient or toxicity

[Jsimo]

So I've got a few of these leaves in only one of my bucket setups affecting the two plants, different strains in that setup. The other setup is doing fine but that one also has two plants of the same strain. When i first noticed it I checked ph and ppm. Ph was good, ppm was down to about half of my other setup. So i did a full res change to get things back to the same. That would lead me to believe it's a deficiency, and it does look somewhat like a potassium deficiency, but i also read that's hard to do in hydro. And the leaves affected after more toward the top of the plant, haven't found anything at the bottom affected yet, but they're mostly older top leaves. I'm not sure if it's taken care of yet or not, since i saw some leaves today that i don't remember being there last night. Anyone have any ideas? One picture is earlier stage, one picture is later.

Forgot to mention, about 3.5 weeks into 12/12

[Toker1]

You say PH has been good....what exactly does that mean? How would you define good PH?

[Toker1]

Understood, but you are hitting 72... so wrapping them will not suffice. You need to lower the ambient or chill the water.

[Jsimo]

Well a chiller isnt in the budget right now. I could throw my pumps on a timer to reduce the heat from those, and i could possibly run them external as well, wouldn't take much to do that and might drop a degree or two. The cement floor is probably 65 degrees so i figured isolating the bucket from the ambient heat a bit more wouldn't hurt, the room itself is usually around 75 degrees

[Toker1]

Yes, get those pumps out of the water and run them inline if you can. For sure!
Depending on how your system is set up, yes...running the pumps on a recycle timer (costs like $30) could be an option.

[Iammygod]

Because potassium is highly mobile within the plant tissue its deficiency starts at eadg of the lower leaves.

if u see the symptom in active growing part of the plant it can be Calcium deficiency.

too much P and K, high RH and low temperature are the main reasons of Ca deficiency.

[Jsimo]

I did give it a half dose of calimagic this round, my base water is about 150ppm already so i wasnt sure if i should go with a full dose. I'm still confused at how my ppm dropped so hard in this line, unless i somehow completely forgot to add something. I'll have to check tonight to see if the leaves got any worse or if there's more of them even after the res change. Just a little nervous trying to figure out what's actually wrong in case it's still an issue.

[Scarletwhitewidow]

Are the roots ok brown of tips and leaf can be root rot bacteria or fungus and called dieback the plant is dieing

[Jsimo]

I haven't looked at the roots in a little while, the water doesn't have any bad smells to it though, but I'll check the roots to be sure tonight. It's only been a few leafs so far, maybe 4 or 5 per plant. I do run hydroguard, and recently started using great white as well to try to keep the roots healthy

[Toker1]

Hydroguard and great white will not do anything if water temps are too high.

[Obi-Wan]

When was the last time you flushed the roots? I used to run into the same problem a few weeks into flower and it drove me nuts. I started giving the roots a 24 hr flush before I flipped to 12/12 and again 1/2 way through flower, I haven’t had the issue since. It could be the start of a lockout or salt build up. Periodically flushing the roots is a good practice to maintain a happy and healthy root system.

72F is not a high enough water temp to cause any noticeable issues or drops in DO levels. 72F is the target temp for my reservoirs and I haven’t experienced root rot, poor growth, or any other negative effects. I actually run a small aquarium heater in my reservoir so I can keep a fairly consistent 70-72F. Far too much is made of the temperature of the water. Dissolved oxygen levels are what matters and they won’t fall below acceptable levels until the water temp exceeds 75F.

[Jsimo]

I don't usually do a flush, i may have to also add that into the regimen for sure, currently changing water is a bit of a pain but i try to do it every week or two. Before the next plants go into flower I'm going to tap into a water line and install a faucet right in my mixing area. So i won't be so turned off by carrying 5 gallon buckets of water back and forth. I may do a flush if things aren't looking up, lights will be back on in about 15 minutes so i can take a look

[Toker1]

72 is up there bro. You are not reaching the DO maximum potential above. Can lead to issues, consider yourself to be lucky to avoid issues at these temps. Not everyone is this fortunate though. Check out the chart I attached. At 68 major drops in DO.

https://www.usgs.gov/media/images/temperature-affects-dissolved-oxygen-concentrations

I never let mine go above 68 because it’s counterproductive to have such little DO in the water.
I copied and pasted this from the website we are all chatting on...
“Many growers aim for their reservoir water to be between 60-68°F because cooler reservoir temps prevent some bad organisms from growing in the first place, and cool water can hold more dissolved oxygen in the 60-70°F range.”

https://www.growweedeasy.com/deep-water-culture-faqs

And there is also this one stating the same. I’m sure I can find more supporting data on this subject.
http://www.just4growers.com/stream/h...d-answers.aspx

[Jsimo]

Not seeing anything too concerning as far as roots go, and no bad smells at all. the problem hasn't seemed to have gotten any worse but it was the dark cycle all day so tomorrow might give me a better idea

[Toker1]

Keeping the temps from fluxing will keep your ph from fluxing.

[Obi-Wan]

Lucky once, maybe. Lucky twice, slightly less likely. After almost 2 years I’m fairly certain it’s not luck at this point.

Bacterial and microbial growth won’t be slowed significantly until the temperature is dropped below 40F. They will multiply at similar rates at whether the temperature is 60F or 75F.

Providing oxygen in order to maintain healthy roots is what is most important. Colder water is one method, but the same results can be achieved with a larger air pump or an O2 emitter. The measurement of DO refers to how much oxygen the water can hold and while those levels change based on temperature, they are irrelevant if the oxygen levels are constantly being replenished.

[Toker1]

You said you were having issues until you began flushing. So maybe you were not so lucky after all. I have been growing in DWC for going on 5 years. Never had a single issue, never had to flush once. 68F is clearly the DO drop off from all the information given above. I have a hard time hearing facts with out some form of verifiable information. Especially when the authors of this website are saying exactly what I said about the water temps above 70 causing the potential for pathogen issues. It’s not as much about the temperature, it’s more about proper oxidation. Which is what controls the pathogens.
And the ability to hold DO means it can not hold any more no matter how much o2 you pump into it. It’s physically in capable of holding more DO with those temps. The chart I posted says it all. I am curious to know your sources for the information you have provided here.

[Obi-Wan]

The issues I had were in no way related to the oxygen saturation of water. They were caused by salt residue accumulated on the roots. Do you currently grow in DWC? I read your most recent journal and your results were impressive but that wasn’t a DWC grow.

The only source I rely on is my garden and what the plants in it tell me, they’re all pretty happy. I did my research before I switched to DWC and I’ve read quite a bit about oxygen saturation in water so you’ll be hard pressed to post anything that I haven’t already read in some form or another. The chart you posted referring to a fresh water river in NJ is only loosely relatable to a DWC system. Unless the DO levels were checked within a mile of a dam release point the surface agitation and aeration just don’t compare.

We agree that high oxygen levels are required to be successful, we just differ on how to provide those high levels of oxygen. Colder water temperatures are absolutely the tried and true method, it’s just not the only way to do it, if it was the only way my garden wouldn’t be what it is.

[Toker1]

I grow DWC in the winter and soil in summer. Because of the temperatures. Oxygen is not soluble in warm water. Do your thing there...but seems like the information available to the rest of the world (plus the authors of this website) are agreeing with what I am saying. Maybe if you provided a little evidence, we could continue discussing this further. As of right now, I respect your opinions, but I think Nebula and Serious have the final say in my book. And I’m going to keep doing what I do. ✌️

[Jsimo]

Yeah this weekend I'll be doing some work to at least try to keep temps consistent if anything. I've got 200 more Watts to pull outta these lights so that's only going to increase temps further. Gotta pick up a 2 outlet timer, and see if i have enough hose to get the pumps outside. Probably gonna run a line from the air pump intake to outside the room as well to pull in cooler air.

[Toker1]

http://compost.css.cornell.edu/oxygen/oxygen.diff.water.html

http://www.k12science.org/curriculum...j/temperature/

[Toker1]

Obi-Wan if you really do have information that the rest of us don’t know, please submit this to nebula. I have done this before with water quality issues. You will need some actual supporting data to back up your findings, but may lead to edits in their website. Plus nebula is cool to work/talk with. Really open minded about making edits.
I will say, I have been testing water in hydro power generation since 2012. Growing in DWC for 5 years...I have never heard this about the drop off at 75 in any situation.
i am always willing to learn, but you must be willing to teach me. I’m the type that needs to read this for myself. I have a hard time believing anything else now days.
I know you are a good grower, which is why I am suggesting you submit your information to the website authors. So we can all learn something new.

[Obi-Wan]

If I had any new information for the authors I would absolutely provide it but given that it was this site’s tutorial where I first got the idea that cannabis could thrive with warmer temps I can’t provide anything new.

This is the full write up from the GWE article you quoted above.



What temperature should my reservoir water be?

Here’s the rule I use: If your grow room temperature is in a good range, then your reservoir temperature is also in a good range. You only really need to worry about your reservoir temperature if your grow room temperature is out of the acceptable range.

Many growers aim for their reservoir water to be between 60-68°F because cooler reservoir temps prevent some bad organisms from growing in the first place, and cool water can hold more dissolved oxygen in the 60-70°F range. However, cannabis can grow and thrive in much warmer reservoir temperatures as long as beneficial organisms are present to fight root rot. In fact, I personally have found that hydroponic plants tend to grow a little slower when their roots are cool, and grow fastest around 75°F (as long as you're using a supplement with beneficial organisms to kill root rot).

In short:

Maintain the temps in your grow room and the reservoir is fine

I personally have found hydroponic plants tend to grow the fastest when the temperature is between 73-80°F, with 75°F being a good temperature to aim for. However, with warmer temps make sure you're using a beneficial bacteria supplement to prevent root rot!


I just followed the instructions, by no means did I break any new ground.

[Toker1]

Yes, I know what you mean with faster growth. In fact, that topic was covered briefly in some of the information I linked a few comments ago. It also said shortly after, growth that is happening too fast can kill a plant as well. Since we both agree with the DO being most important factor. And o2 being significantly less soluble in warm water, I think we agree conceptually. We have different approaches to risk mitigation and what’s best for our girls. I’m sure there are several un-discusses variables (such as water source and likelihood of pathogens present) that make each of our actions prudent to our own set of variables. In short, what works with your grows might not work with mine and vice versa.
Thanks for the good discussions on this topic.

[Jsimo]

No progression of the leaf issues after the light cycle. I think that the plants are just sucking everything out and i got a deficiency. Seems like i can no longer go a 2 weeks without a res change or at least replenishing nutrients, instead of plain water. The other bucket is now down to 680 ppm when it started at 1050 when i changed it last week. No deficiencies starting yet but I'll be changing that one tomorrow morning.

Completely different setup than i used my first grow, so a completely new learning experience when it comes to nutrient needs.

[Obi-Wan]

Yup, they tend to display more aggressive nutrient uptake in the first half of flower.

[Jsimo]

Res changed, pumps moved external as it's hot this week and our floor ac units aren't keeping up. Found the water above 75 tonight. I'll be keeping an eye on the roots a bit more this grow since it's my first during the summer. Should be there last summer without Central air as well thankfully. But plants looking healthy as far as i can tell. At least they're a huge improvement from last grow!

[Toker1]

Ouch! Well, they look plenty healthy right now. Just going to get hotter the next upcoming months. In desperate times, I put frozen water bottles in my reservoirs. Change them out 2-3 times per day. It can help in a crunch, but sometimes is a big pain.