Need help, was yellowing do to high pH?

Hello all, I started my first dwc grow and need some input. My seedling is a 7 days old today and is sprouting its 2nd set of true leaves. To me the color looks a tad bit yellow. I’m thinking it may be pH issues, any suggestions?
Setup: 1.5’ x 2’ x 3.5’ cabinet
400 watt MH @ 18/6
4" inline vent exhaust running through my light housing to vent heat.
120mm computer fan intake
4-gal tote with 4.5" net pot running a drip system until the roots grow
10-gal aqaurium air pump connected to a air ring
Temps run 75-83 with 60% humidity.
I also made a gallon of CO2 with sugar and yeast in a milk jug.
Today I just checked my pH with a pen tester, and it was around 7.9, I know that’s high so I downed it to 6.3.

You did the right thing, you want to keep your pH at 5.8 - 6.0 if at all possible.

I read a lot and saw between 5.5-6.5 was tolerable. I’ll down it a little more next reservoir change. I didn’t think it was nute deficiency as the plant is so young still. Thanks for your input.

Target for hydro is 5.8 and I would rather err on the 6.0 side rather than too low. Below 5.5, at about 5.4 root damage will be caused by the acidity, and yes you probably wouldn’t see too many problems as high as 6.5, but in hydro I’d try to keep it well below 6.3 for optimum results.

Per Robert himself in this article http://www.theweedblog.com/what-is-the-best-ph-level-for-marijuana-plants/

He states keep pH between 6.0-6.5. I feel ok with my water at 6.3. Didn’t mean to undermine your advice. I just could’ve swore I read that the upper and lower limits were 5.5-6.5 and this is where is saw it.

That is a broad general description. The target range for hydro is 5.8 and for soil it is 6.5, Latewood and others can confirm this.

Another thought, some types of rockwool in flood and drain tables might need to be kept a bit more acidic to compensate for the alkali properties of many of the “rock” minerals found in the melted rock and then spun like fiberglass material. If you notice, in that short fragment of his comment, he almost contradicts himself, probably just an on the fly response and he didn’t explain himself as fully as he could have, but he says about a hydroponic solution at 5.5 and then he says it grows best in water(same thing as hydro) between 6.0-6.5?

Normally you shouldn’t have many problems as high as 6.5 in hydro with a good balanced nutrient system, but it is still not an ideal pH for your hydro, again, you should try and keep it much closer to the 5.8 and yes, the max range can be between the low of 5.5 and high of 6.5, this is the max range, but not the ideal target.


Day 10 now. I’m not sure if 5.7 pH water helped, or the 1/4 strength sea kelp nutes that I gave did her the trick? Maybe combination of both? But my plant was a bit pale green two days ago, and now she’s bright, healthy green. Thanks Mac for the advice.

Question: why is she leaning like a gangsta to one side? The light is directly above, walls are painted white, no reason for it to reach sideways. Also her leaves have no space whatsoever In between her first set to the second. Light too close? I don’t mind growing a shrub, I only have 3’ of height to grow anyways, then she’d touch the light.

It doesn’t seem to be showing any other characteristics as if it is reaching toward anything, such as a light source. I’m not sure, did it just get nudged or bumped?

Also in a recirculating top drip DWC, like what I think I’m seeing in your set-up, you do want to be very careful the stem’s “trunk bark” isn’t getting or staying too wet, so as to avoid a pythium stem rot infection.

I’m also noticing the slightest hints of nute burn in the tips of those leaves, so keep an eye on those, it might be just related to the pH being off if your EC/PPM isn’t too high.

Yes it is drip for now until the roots grow to the reservoir. I also noticed the tips a little burnt, but that was from several days ago before I corrected my pH problem. Thanks for the advice on keeping the stem dry. I have the water tube off to the side, it’s not directly on the plant. Maybe I might’ve nudged the plant while adjusting the water. But it wasn’t leaning like that yesterday. We’ll see. I’m just happy it’s healthy and getting bigger everyday.

I think it’ll do just fine.

And I don’t see any reason to very carefully try and get it pointed upright in the right direction again.

And can you rotate it’s container or adjust the tube to have it a little further from the stem?

Yes I can rotate it, the drip tube will end up at the edge of the pot. And I’m not too concerned about the “gangsta lean” it’s LST’ing itself for me lol. I was just wondering what may have made it reach to the side.
I’ll go ahead and rotate it this afternoon, the plant is in its dark period right now.

Yeah, that’s fine, don’t interrupt the dark period.

If there is not a better light source or something obvious, I’m not sure why it is leaning. I couldn’t see very low in the angle of the photo that you show, but I don’e see anything that looks damaged that could cause a plant to lean over either.

Letting it right itself as a sort of LST is also perfectly fine.

I’ve been combating a constant pH battle. Everyday it climbs up about 1.0 and I have to down it to 5.7 if I miss a day it’ll be up in the 7.0-7.2 range. Like I found it this morning. Any reason why? I can’t imagine my plant is making it fluctuate that greatly. I mean it’s barely 3" tall and just sprouting its second set of leaves at day 16 since sprouting. I’ve switched the lights from my 400watt mh to something a little less intense. Two 26 watt cfls about 5" away. It actually looks the best it’s ever looked so far. I have that little burn, and what appears to be N deficiency, from my pH being way off early on. But roots are finally showing through the bottom. Any advice to handle the pH swings? Or is this normal?

The weird twisting is probably from the pH as well.

The only things I can think of, is for one, aerating water can and usually will change the pH more towards the acidic. But normally you shouldn’t be having such a drastic quick change, the other things that might be contributing is the type of rock, maybe if that rock has a lot of iron in it or some other mineral/chemical composition that is leaching into the water and could contribute to a dropping pH and the other, probably more likely, thing is most of that CO2 from your set-up is being sucked in by the air pump and fed through your water, with likely none of it doing much good for the plants, especially such small plants. Higher levels of CO2 bubbling through water will certainly create carbonic acid. And you want high oxygen levels in your water, not high CO2 levels.

Aiight, thanks man. I’ll ditch the CO2 for now. Hopefully it’s not the rocks as its a bit too late to change it now. Also, my aquaponics is not experiencing any pH swings. And I have like 24, 3" net pots with the same black cinders. But I only got lettuce green onions and cilantro growing in that bad boy. I wish I could clone and slap all 24 with cannabis. But my wife would kill me, not to mention it would stink like a mofo during flowering. Maybe it was the co2 like you suggested. Thanks Mac!

I would say if your aquaponics is doing pretty good, it probably isn’t the rocks.

Something to think about when the plant gets bigger, if it is the CO2 that seems to be causing the problem, is aquarium air pump hose is pretty cheap, you could try putting the pump outside the grow room, so it only has access to the highly oxygenated air outside the grow room to pump into the water.

ive come to grips with the fact that my plant just raises the pH as it consumes nutes. I check the pH daily and adjust accordingly. The 3rd set of leaves are coming in and they are looking nice and green. The roots are also showing out the sides. I will be stopping the drip soon as I feel it is no longer necessary. Thanks for all your guys help. I’ll continue to seek help and provide updates along the way.

Ahh, I’ve been thinking about this and did not mention before, and also I am not entirely sure of exactly what nutes or concentrations you are using and so, yes, absolutely, depending on the mixture, if it doesn’t have enough stable minerals in it like calcium and silicon, pH will often slowly move towards the acidic or go down.