pH questions

[UrbZ]

So I just have a couple questions regarding pH.

1st my cherry pie had a pH runoff of 6.7 last feed. I fed with 5.8 pH. The last 4 waterings/feedings have all been pH in at 5.8 but I'm not getting any significant drop in runoff. Each of the 4 last feeds runoffs were as follows.

1st - 6.82
2nd - 6.91
3rd - 6.88
4th - 6.73 Last nights feed.

So my question is should I flush to get to the range I'm looking to hit around 6.3- 6.5 pH or continue trying to drop it with 5.8?

My second question is my 3 other plants had a runoff of 6.4 and 6.45 on two of them but the third had a runoff of of 6.85. Same water, same soil, same strain and same enviroment. My question is what could cause this?

Third question once I reach a specific range I'm trying to achieve say 6.4 pH runoff what level water should I be putting in to maintain that pH level in my soil?

Thanks in advance everyone.

[gdogfunkly]

What kind of soil are you using? I'm using FFOF and was told that it has pH buffers in it. Something similar might be happening with your soil to cause the offset. Are the plants showing any issues?

[UrbZ]

No no real issues one is showing a little deficiency on the tips of newest growth but its also ready for a feed so im thinking that should work out. No real slowing in growth either. The cherry pie even with the high runoff is on average 1.5 - 2 inches of growth a day.

My mix is local. The mix is roughly 35% perlite, 15% sphagnum, 25% soil and 25% coco. I added extra perlite myself I did not like the drainage without the extra.

[D.A.A.S.69]

If they are doing ok, I wouldn't worry with it, as long as you got it in range, it will all work out in the end.

[UrbZ]

That's kind of been my plan the whole time, sticking to my current groove. Everything seems fine. Just kind of learning the nuances of this. Kind of weird to me that one is so out of range compared to the other two with everything exactly the same.

I just had a few people suggest to try and them into a lower pH range. Few of them i got down. Those few do seem to be the fastest growers in the tent though.

[9fingerleafs]

I would water at ph 5.5 until runoff reaches 6 then keep watering at 6. Use ph down to lower ph. Dilute first in half a cup of water and add slowly to nutrient solution

[D.A.A.S.69]

What 9fingers said above.

[UrbZ]

I will try this on the plants with high ph runoff. For what ever reason ph seems to perplexing me the most of all the growing stuff.

[Iammygod]

Run off tells nothing about substrate ph.
You cant measure substrate ph by measuring runoff ph. All material you named have their own Cation Exchange Sites. Specially Soils have high CEC. When water passes through substrate, the ions in water will exchange with the ions in CEC sites. These exchanges are the main reason that run off ph is not the substrate ph.

if the run off of 6.7 is the reason you want to change substrate ph so let me say that 6.7 doesn't mean you need any change.

Same environment? I dont think so. Each of your plants face different light level, different air temp and humidity(yes, diffrent!), different air movement and diffrent amount of in-out water. You can't reach the same environment without scientific acknowledge and equipments.

make sure your ph meter is calibrated and you always adjust water ph before watering.