pH dropping regularly...is this range normal?

[Brother_Antioch]

Hi, folks. Have a question for you hydro growers out there.

So, I've noticed over the last several days that my pH is dropping at a much higher rate than previously. Since this is my first try at growing in a hydroponic environment, I'm not sure if it's normal at this stage or not. I've looked on several sites on the web and get conflicting answers. Currently, my pH is dropping roughly 0.25 every 8 hours or so on average. I'm in the late veg stage of the grow, most likely flipping her to 12/12 within the next 5 days. Prior to a week or so ago, my pH would start off at 5.8 and slowly drift up to 6.2 over a period of 5 days or so, when I'd adjust it back down to 5.8 From what I read, that's normal behavior. EC is staying stable, with a very slight decline in EC/PPM (started at 1.295 and it would be down to 1.1 in about a week) which from what I understand is normal healthy behaviour meaning she's eating at a healthy rate and the solution is in the sweet spot.

Roots are growing rapidly, and are still very healthy. Other than a slight tan colour to them from the Flora Micro and CaliMagic, they are fine. Zero slime at all, no off smell to them, all the signs of a very healthy root ball. The plant herself is looking very healthy. Nice emerald green colour, great positioning, no signs of nutrient deficiencies, no clawing, nice sharp serrations on the new growth, all the signs of a healthy grow (from my limited knowledge).

Here's the readings for the last 5 days. Readings were taken in the morning, mid afternoon, and evening. The ones that have two readings are "initial" then "adjusted up to" numbers. I've been keeping up on it to make sure they don't drop to really bad numbers, and I'm going to do a res change this weekend when I flip to 12/12. These numbers are from the morning after my last res change until this afternoon about an hour ago. I'm trying to keep it so that there's a low of 5.8 and a high of 6.2.

5.89
5.68
5.57 up to 5.89

5.69 up to 5.87
5.71
5.61

5.63
5.44 up to 6.26
6.14

6.2
5.85
5.72

5.53 up to 5.98
5.66 up to 6.23

I'm using distilled water only, and using Botanicare Silica Blast, CaliMagic, Flora Trio nutrients and H2O2 to maintain a sterile environment (adding 16.9 ml with res change and 12.5 ml every 3 days after that). I'm making sure to mix them in the right order, and to leave some time after Silica Blast (about 30-45 minutes) with an air stone in the change bucket before adding the CaliMagic, then waiting another 15 minutes before adding the Micro, Grow and Flora (in that order) and stirring well between ingredients. Res temps are now holding at a steady 66.2F all day and night. Air temperatures are 72-72F at night and 80-82F during the day, VPD is right on 0.9 kPa during the night and 1.2-1.25 during the day.

Bottom line, is this somewhat normal behaviour or is there something more sinister that I should be looking for? I've posted a few pics here of her so you can see how she looks for visual clues on the canopy. On a secondary note, does she look ready to flip to flower within the next 5 days? I am aiming for 65-70% canopy filled but don't want to over do it and have a jungle when the stretch happens.

Appreciate any and all help, advice and information on this, so please, feel free to chime in, ask any questions you have, or thoughts from your own experiences.

Overhead:

Straight on at canopy height:

General overall shot:

Again, thanks to all who chime in and know that it's immensely appreciated.

Cheers,

BA.

 

[Grownsince95]

If you've ruled out root rot it sounds like a buffering issue and it's totally normal in distilled water. If your EC is dropping it's just the metabolism of the plant doing its thing. Increasing the feed will bring it more under control.

Unless you decreased the amount of silica (your main buffer) or added another air stone (more carbonic acid) I would keep rocking what you're doing.

 

[Brother_Antioch]

If you've ruled out root rot it sounds like a buffering issue and it's totally normal in distilled water. If your EC is dropping it's just the metabolism of the plant doing its thing. Increasing the feed will bring it more under control.

Unless you decreased the amount of silica (your main buffer) or added another air stone (more carbonic acid) I would keep rocking what you're doing.

Thanks for the response, Grownsince95. I'm now 100% certain that's what the issue is and after a couple of days of babysitting the levels, it seems to have stabilized itself. This morning I was back up to 6.15 and by late morning, up to 6.22, which is much closer to the slight upward drift I'd had prior to this issue. I've brought it back down to 5.85 as of noon today, and will see how it trends this evening. She is drinking like a recently divorced single dad who lost the house, though, with a stable EC, so it looks like all is good.

Definitely not a root issue, as I did a good inspection of them yesterday evening. Zero slime, rot, smell, nothing to concern myself with. I then gave them a very gentle massage to loosen up the ball a bit without doing any damage to them. Seems it was, to quote Shakespeare, "Much Ado About Nothing".

I appreciate the help, as always.

Cheers,

BA.

Edit: you mention air stones. I currently have 4 in the reservoir to keep it super oxygenated. Do you think I'd be better off by removing one? Each is on its own feed line with shut off valves, so it'd be as simple as twisting a knob.

 

[Grownsince95]

Thanks for the response, Grownsince95. I'm now 100% certain that's what the issue is and after a couple of days of babysitting the levels, it seems to have stabilized itself. This morning I was back up to 6.15 and by late morning, up to 6.22, which is much closer to the slight upward drift I'd had prior to this issue. I've brought it back down to 5.85 as of noon today, and will see how it trends this evening. She is drinking like a recently divorced single dad who lost the house, though, with a stable EC, so it looks like all is good.

Definitely not a root issue, as I did a good inspection of them yesterday evening. Zero slime, rot, smell, nothing to concern myself with. I then gave them a very gentle massage to loosen up the ball a bit without doing any damage to them. Seems it was, to quote Shakespeare, "Much Ado About Nothing".

I appreciate the help, as always.

Cheers,

BA.

Edit: you mention air stones. I currently have 4 in the reservoir to keep it super oxygenated. Do you think I'd be better off by removing one? Each is on its own feed line with shut off valves, so it'd be as simple as twisting a knob.

Nah don't fuck with them if you've had them in the whole time it could make it worse you don't wanna give yourself more things to adjust. I only mentioned it because if it was recently changed it could explain a change in pH but ur good. You just have a heavy cation exchange going because of very hungry plants.

 

[Brother_Antioch]

Nah don't fuck with them if you've had them in the whole time it could make it worse you don't wanna give yourself more things to adjust. I only mentioned it because if it was recently changed it could explain a change in pH but ur good. You just have a heavy cation exchange going because of very hungry plants.

Sounds good. I'm doing another res change this weekend anyway when I flip them to 12/12. Hydro certainly is a different beast than growing in Promix!

Cheers,

BA.

 

[NairnM16]

I’ve had a similar problem to this, what ph up/down are you using? When I was in hydro,

I was using organic ph up/down,
My h202 would strip it from my tank nd
It was binding to my sylicone and creating like a small film gunk layer,

No longer use hydro but switching to synthetic up/down fixed this for me

I could be wrong just a thought

 

[Brother_Antioch]

I’ve had a similar problem to this, what ph up/down are you using? When I was in hydro,

I was using organic ph up/down,
My h202 would strip it from my tank nd
It was binding to my sylicone and creating like a small film gunk layer,

No longer use hydro but switching to synthetic up/down fixed this for me

I could be wrong just a thought

I'm using Technaflora pH up and down, which is a synthetic ph u/down. There's no sign of any film on anything, so I don't think that was the issue. The first 4 res changes never had an issue, so I'm thinking it was just a shift in the plant's metabolism as I get to the end of the veg stage. I'll most likely be flipping her to 12/12 tomorrow afternoon, so I'll be remixing the solution anyway. For now, though, it seems to have stabilized, and gone back to a slow and steady upward drift while the EC continues it's slow and steady downward drift.

Thanks for chiming in, though. I had no idea that there could be issues with the ph up/down solution being organic vs. synthetic. Guess I just got lucky when ordering the solution! Even a blind squirrel finds a nut once in a while, right?

Cheers,

BA.