pH Crashes and EC Spikes in DWC - is this the issue?

Hmm...I thought I could see some little fried tips there on the second pic. Plants that size shouldn't burn at 1ec, they should be able to handle 2ec without stressing.
Can't remember if it's P or K that causes the tips but its one of them.
What exactly are you feeding them?
Just checked but couldn't see it.
Using pk booster by any chance?
Yep, some fried tips.

Here's the nutes I'm using: https://lotusnutrients.com/pages/easy-guide-and-recommended-hydroponic-feeding-schedule

Bloom and Boost are what I'm using right now.

So, a couple things:

* There are two different strains - both supposedly Indica-dominant, but one is definitely tall and lanky and the other short and stubby
* The shorter, bushier plants do NOT have nute burn; taller ones do

My interpretation was the shorter plants are hungrier and the taller ones get burnt way before the shorter ones do. Some of the lower leaves got burnt a few weeks back on the tall ones.

Right before the flip I was rocking along about 2.2 EC (feed schedule called for 2.8) and relatively stable pH when I noticed the tips on the taller plants got fried, so I backed it down to 2.0EC, - THIS IS ABOUT THE TIME I STARTED HAVING BIG PH DROPS (for whatever reason typing this out made me see that more clearly) but overnight it jumped to 2.9EC, so another res change and backed it down to 1.5EC - it was relatively stable for a couple days, EC dropped to 1.3 so I topped up with nute-water (probably should have just used plain water until the res change) to 1.6, then another pH crash to 4.6pH.

Res change to 1.5EC - next day was stable pH and 1.3EC, topped up with nute-water to 1.4EC; 12 hours later another pH crash to 4.7 and EC up to 1.6.

After that I've been walking down EC all the way to currently 0.6EC, which keeps the EC relatively stable and good water consumption, but pH drops into the 4s every 12 hours.

After reading what I typed, it almost seems like when I top up with nute-water I'm locking out at least some of the plants - which sort of makes sense, as I understand EC only indicates the level of TDS, not what KIND of TDS, so the plant may uptake X and Y, but have a lot of Z left in the res, then when I top up with nute-water I'm adding more of X and Y, but also more of Z - which could raise Z to lock-out levels, then somehow that makes the pH crash.

Wonder if I do a rinse with pH'd water for a few hours, then a res change with fresh nutes to like 1.0EC (and walk up from there to maybe 1.4 if it is stable), then only top-up with plain pH'd water between res changes would fix the issue...seems worth a shot.
 

principlesarelife

Active Member
TLDR: get a bigger reservoir. more water = larger buffer to PH swinging


this is why i went to a 30 gallon tote for my 1 lady under my 200w cob in my 2x4 space

I started dwc recently... in a 5 gallon stand alone paint bucket.
i began experiencing the same problem of ph dropped in the 4's and the ppm unchanged/increasing. if i added ph up to the right PH... within 12 hours the issue returned

PH drop wasn't an issue for me until she got to a respectable size in veg

after some research i discovered PH swinging down means water drinking & nute leaving.
so i upgraded to a 30 gallon tote. no more ph issues :)
 
TLDR: get a bigger reservoir. more water = larger buffer to PH swinging


this is why i went to a 30 gallon tote for my 1 lady under my 200w cob in my 2x4 space

I started dwc recently... in a 5 gallon stand alone paint bucket.
i began experiencing the same problem of ph dropped in the 4's and the ppm unchanged/increasing. if i added ph up to the right PH... within 12 hours the issue returned

PH drop wasn't an issue for me until she got to a respectable size in veg

after some research i discovered PH swinging down means water drinking & nute leaving.
so i upgraded to a 30 gallon tote. no more ph issues :)
Good input, thanks. It's starting to make sense why you see so many single plants in buckets that size.

Can't move the plants for this grow, but definitely taking that into consideration when I build my rig for the next one.
 
Yesterday I dumped the res and filled with pH'd water (RO) only, then dumped it again (to get the stuff at the bottom I couldn't get the 1st time) then filled with pH'd RO water and let it bubble overnight. EC was 0.15 last night (net 0.1 as my RO water had 0.05EC base) and pH 6.3; when I came back today it was 0.18EC - not a huge change, but it looks like some nutes leeched out overnight. That supports the lockout theory somewhat. pH crashed again from 6.3 to 4.8 -not sure why but hopefully these steps fix it.

Res change this morning to 0.62EC (will increase if they handle it well) and 6.14pH. Buds are forming nicely and starting to thicken up. However, I do have burnt tips. Will see how this holds over the next 24 hours or so and prepared for another res change.
 
Yesterday I dumped the res and filled with pH'd water (RO) only, then dumped it again (to get the stuff at the bottom I couldn't get the 1st time) then filled with pH'd RO water and let it bubble overnight. EC was 0.15 last night (net 0.1 as my RO water had 0.05EC base) and pH 6.3; when I came back today it was 0.18EC - not a huge change, but it looks like some nutes leeched out overnight. That supports the lockout theory somewhat. pH crashed again from 6.3 to 4.8 -not sure why but hopefully these steps fix it.

Res change this morning to 0.62EC (will increase if they handle it well) and 6.14pH. Buds are forming nicely and starting to thicken up. However, I do have burnt tips. Will see how this holds over the next 24 hours or so and prepared for another res change.
10 hours after res change EC rose from 0.62 to 0.67; pH dropped from 6.14 to 4.75 (wtf?). They drank a lot more than usual.

I'm new to this, but it's odd to me that I'm seeing over-feeding signs at a 0.6EC going into the 3rd week of flower...

So I topped-up with pH'd water only (no nutes) and brought EC to 0.55 (since EC was rising and pH falling, which signals over-feeding and calls for reduction in EC) and pH to 6.0. Will check again tomorrow. Burnt tips, but otherwise plants seem OK and buds forming everywhere.
 
Plants are healthy, I'm colour blind so see just fine under blurples lol.
Nutes should be around 1.5ec for plants that size.
Calmag helps balance the ph swings. 0.2ec worth of that would be about right. Even if you've got hard water it's best to add a little just for the buffering.
Trouble you for a second look?

Two things - 1 is a top-down shot which showcases the burnt tips. I can't for the life of me figure out why I'm frying the tips when I'm down to EC0.5 in the 3rd week of flower...does this look like over- or under-feeding to you? My thoughts were over-feeding and locked-out, but I have the EC so low I don't see how I could be over-feeding them.

Next - I"m unable to pull the top off the res (scrog, etc.) but I jammed my phone down into one of the empty net cups and took a couple snaps. There's a little bit of "slime" on one or two of the roots, but I am not experienced enough to know if this is root rot or just from the nutes. Appreciate your thoughts.
 

Attachments

Further update:

Changed res yesterday morning to 0.62EC and 6.14pH. Nine hours later it was 0.675EC and pH 4.75. Added pH'd water (no nutes) to EC0.55 and pH6.0.

Today at noon it was EC0.6 and pH 4.1.

Added pH'd water to EC0.5 and pH 6.0.

I can't for the life of me figure out why EC is going UP when it's already so low. Seems like an over-feeding situation by the rising EC and plummeting pH, but I'm at 250PPM/0.5EC in the 3rd week of flower, which is WAY less than everyone says it should be.

ALTERNATE THEORY: Any possibility the EC could be too low, resulting in a higher EC/nute content in the plant vs. the res, with the plants leeching nutes as a result of the imbalance, and the nutes being leeched are lowering the EC?

I could bump the EC up to 1.0 or 1.5, but even at 0.6 or 0.7 I'm seeing fried tips, EC raises and pH drops. Ordered some cal/mag should be here tomorrow, so will try that as well - seems like that would NOT be a silver bullet to fix all these issues though...
 

desol

Active Member
pH crashes and ppm spikes. This is exactly what my system does. It's because of transpiration. The plant is using lots of water...a little nutrients...but nothing else. The plant doesn't use pH down. So when the water drops the concentration of pH down increases and pH drops. At the same time the concentration of ppm's goes up. You need to find a way to keep the water level consistent. This is why in my system I'm going to hook it too a bigger res, and autofeed pure water into the system as needed. This will keep the levels all more stable.
 
pH crashes and ppm spikes. This is exactly what my system does. It's because of transpiration. The plant is using lots of water...a little nutrients...but nothing else. The plant doesn't use pH down. So when the water drops the concentration of pH down increases and pH drops. At the same time the concentration of ppm's goes up. You need to find a way to keep the water level consistent. This is why in my system I'm going to hook it too a bigger res, and autofeed pure water into the system as needed. This will keep the levels all more stable.
Sorry to hear that - definitely a frustrating issue. My grow has gone from fun and enjoyable to tedious and laborious...I'm spending 30-60 minutes at least twice a day just to keep the pH from dropping into the 3s...

I hear what you're saying, but that's not what is happening to me. I don't use pH down, so it can't be increasing. My pH never raises to a level where it needs pH down. I change a res and leave it at 6.2 and it's 4.2 12-hours later. I do use pH Up, but if what you say above is true, it should be concentrated and raising my pH through the roof - instead it's always headed down into the 4s.

I do agree with you on the larger res. Definitely switching up for the next grow, but not possible now as I have two trellis nets, LST ties and 5' plants that I can't move around very much. Also agree that the plants are using water but not much else - the 420 Mag chart says to lower EC, but I'm already at 0.5EC/250PPM in the 3rd week of flower which seems really low.

On a positive note, 20 days into Flower my buds are forming and the plants generally look healthy (other than the roots, which appear to have some root rot starting). Temps are an issue for me.
 
UPDATE: People have mostly stopped replying here, but in case someone else has this issue down the road, I will keep posting my efforts and progress (or lack thereof).

Same issues persist. I am doing res changes and lowering EC per the 420 Mag chart (and per my burnt tips) - I am topping off with just pH'd water (to try to avoid excess nutes of X, Y or Z since we can't tell exactly what type of nutrients they are drinking), so the EC goes down slightly each day as I dilute the mix. Then when I change the res I bring the EC up a little higher - but so far just more of the same.

Today I drained the res, filled with pH'd water, drained it again, then filled about half-way with pH'd water and let that run for about 8 hours. When I left it the EC was 0.19EC at Noon and 8pm it rose to 0.27EC. pH dropped from 5.5 to 4.5. Somehow nutes are still leeching (or otherwise EC is rising) even at 0.19EC/100PPM...

5-Way Punch - Today I:

1 - Added hydroguard to the fresh nute mix at 2ml/gal - I have been doing this for a week or so to fight what I think is a start of root rot (high temps)
2 - Added Cal/Mag (Botanicare) to the fresh nute mix at 3ml/gal (I am using RO water)
3 - hooked up a new air pump (I was using EcoAir2 at 126 GPH)- found a new one that pumps out 332 GPH. Immediately noticeable difference in bubbles (hopefully oxygenation too to fight anaerobic bacteria) - hopefully this will eliminate the acid rain issue as a potential cause of the pH drops - air pump is outside my grown tent
4 - res change and pH water rinse (trying to get excess salts and any other nasties out)
5 - added the dehumidifier and adjusted downward - my RH was previously in the 70s and is now between 55-65%. Temps have increased a little from the dehumidifier, and are in the upper 70s and low 80s - hopefully this is OK under my LED, but res water temp is in the 70-76 degree range, which is high

If this doesn't work, future efforts likely to include:

* Great White
* H202 - this seems polarizing - some people swear by it, others say they lost their whole crop
* Adding tap water to the nute mix (although my tap water TDS is pretty high in San Diego (like 300-400 PPM) - not sure about this one)
* Somehow chilling my res water (not buying a $1,000 chiller - maybe ice cubes or frozen water bottle)

Will update with results.

I have a new theory on the burnt tips if interested: plants are doing well, so I don't think it's overfeeding and nute lock (in the traditional sense). If you look at a pH chart and see what nutrients are absorbed in what amounts in the 4s pH-wise, there are certain things the plant is getting a lot of, and others it is not getting much of. My theory is the stuff that's readily absorbed at 4.5 or 5pH is causing the burnt tips, since my plants sit in that water for some time on the daily (despite my 2-a-day efforts). I think they're still getting some other stuff and developing, but if I can keep the pH stable I think the burnt tips issue will go away.
 
Now that you have experienced the downside of not using calmag in ro water you should be ready to start growing some buds now.
Company I bought my DWC rig from and the nute company were quick to dismiss cal/mag, but I've seen a noticeable difference in just a day. Thanks to the bright folks here for the advice!
 

desol

Active Member
Sorry to hear that - definitely a frustrating issue. My grow has gone from fun and enjoyable to tedious and laborious...I'm spending 30-60 minutes at least twice a day just to keep the pH from dropping into the 3s...

I hear what you're saying, but that's not what is happening to me. I don't use pH down, so it can't be increasing. My pH never raises to a level where it needs pH down. I change a res and leave it at 6.2 and it's 4.2 12-hours later. I do use pH Up, but if what you say above is true, it should be concentrated and raising my pH through the roof - instead it's always headed down into the 4s.

I do agree with you on the larger res. Definitely switching up for the next grow, but not possible now as I have two trellis nets, LST ties and 5' plants that I can't move around very much. Also agree that the plants are using water but not much else - the 420 Mag chart says to lower EC, but I'm already at 0.5EC/250PPM in the 3rd week of flower which seems really low.

On a positive note, 20 days into Flower my buds are forming and the plants generally look healthy (other than the roots, which appear to have some root rot starting). Temps are an issue for me.
Hmmm yeah. Temps aren't an issue for me. I don't use a tent and my buckets are directly on the concrete. Keeps my water temps pretty cool.

"I change a res and leave it at 6.2 and it's 4.2 12-hours later."

How much water have you lost in that time as well?
 
It sure looks like you got the dreaded root rot. Note the tangled, clumped together, orange color on roots. I had near identical symptoms: EC "sweet spot" kept dropping, pH swings, growth stopped. I didn't notice the pythium issue because plants were doing well in a scrog, by that time I checked they were much worse than yours. Likely cause was DWC water temps too high and marginal air. I used Southern AG Garden Friendly Fungicide (Bacillus amyloliquefaciens), addressed the temp and air issues, and they recovered nicely.
 
Hmmm yeah. Temps aren't an issue for me. I don't use a tent and my buckets are directly on the concrete. Keeps my water temps pretty cool.

"I change a res and leave it at 6.2 and it's 4.2 12-hours later."

How much water have you lost in that time as well?

So with four plants they are drinking about 1,800-2,400ml (my math is rough but say 1/2 - 2/3 gallon) every 12 hours or so.

The tent makes it tough to control temps, but where I live there isn't another option. I could buy a portable A/C, but the exhaust would just be going back into the room where the tent draws its air, so hot room = hot tent, seems like it would be a waste of $300 for A/C. I'll move the tent or figure something else out for the next grow - just want to get through this one.
 
It sure looks like you got the dreaded root rot. Note the tangled, clumped together, orange color on roots. I had near identical symptoms: EC "sweet spot" kept dropping, pH swings, growth stopped. I didn't notice the pythium issue because plants were doing well in a scrog, by that time I checked they were much worse than yours. Likely cause was DWC water temps too high and marginal air. I used Southern AG Garden Friendly Fungicide (Bacillus amyloliquefaciens), addressed the temp and air issues, and they recovered nicely.
Hey there - yeah, I think it's starting. I've been fighting it with bacillus (hydroguard), with not a lot of effect. Maybe holding it from getting worse, but not really clearing it. I just got some Great White today, so I'll include that with the next res change and see what happens.

I had a 126GPH Eco2Air pump and just replaced it a couple days ago with a 332GPH pump - definitely more bubbles. Not sure how soon I would notice a difference with that - also, the water temp is making oxygen use an issue.

I'm at a loss on the water temps. I could try throwing some ice cubes or a small water bottle in there, but wonder how much effect that would have/how long it would last when it's 79-82 degrees in the tent.

If Great White doesn't help (in conjunction with hydroguard and the bigger air pump), I think I'm forced to try a sterile res and H202 everything for the rest of the grow...which I'm on the fence about as some say it's great and others say it killed their whole crop.

What did you do to address the temps? Air temp and they water temp as a result thereof? Or did you just address water temps?
 
Water temp is crucial in dwc. 68f is considered ideal, 72f ok, 75f+ danger zone. I had to turn on my AC which I was trying to avoid. One heat wave was all it took to light the pythium fuse. Use a liberal dose of the hydroguard and great white bennies. Southern AG GFF is very similar to hydroguard but is literally a million times more concentrated. Ultimately, you have to get the water temp in check. Summer and dwc is bad combo for many.
 
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