Does pH drift occur in soil as it does in hydro?

[ballplayer 2]

When using tapwater in my grows i notice that after 24 hours the pH had drifted from optimal to the mid 8's. I use hempy buckets for some, and peat based soilless mixes for others. The water going into my hempy's is 5.5-5.7, the output coming from the drain hole ends up coming out in the 8+ range. Is the same thing happening within the meduim of my soilless mix? is that nasty upward drift taking place? Both seemed to be experiencing problems, just wondering if this would explain the problems these plants?

Probably going to switch over to all RO, just wondering about the science of this phenomena.

 

[az2000]

Is the same thing happening within the meduim of my soilless mix? ... just wondering about the science of this phenomena[FONT=Arial, Helvetica, sans-serif]. [/FONT]

The science seems to be that water absorbs carbon dioxide from the atmosphere. I can measure a glass of tap water, let it sit uncovered for 5 days and the PH will go up to close to 9. I don't believe it's anything the water company adds because I've done the same test using RO water.

To your question about soilless. Yes, you'll see some drift up. But, because the medium drys while the water absorbs carbon from the atmosphere, it shouldn't go up a great deal due to this process. (A hempy has a pool of water which is more like the glass of tap water mentioned above.).

I'd be worried that, if you pour ph 6.2 water into your soilless (peat) medium, and get ph 6.6 out, that you're soil's PH is too high (close to 7.0). I.e., that wouldn't be the result of water sitting, absorbing carbon. It would be water affected by the medium it flowed through.

 

[sourpuss]

Use lime, dolomite lime, powdered. Is your peat promix?

 

[FreedomTRAIL]

How do your plants look? Got a pic?

 

[ballplayer 2]

I dont have a pic. This is from a grow last fall. I got discouraged from consistent failures, and have not attempted a grow in some time.

I have several theories as to what my problems may have been. It may have been bugs...but I'm not certain...leaning away from that theory. Need a scope or possibly camera with macro lens.

The problems that seem more likely to me right now are overwatering, dry heat (Vapor Pressure Deficit), and possibly a skyrocketing pH.

The reason why I suspect pH was from my hempy bucket. I would prepare my nutrient mix and apply it at pH of 5.8-6.1. Within 24-48 hours the runoff from the bucket drain hole would be ridiculously high 8+. That is why I asked about pH drift within soilless mediums as well. There was powdered dolomite lime added (real dolomitic limestone, not quick lime). No lime in the hempy's of course, but a 3:1 perlite/vermiculite mix.

I think I may have been overwatering as well, though I did add quite a lot of perlite to my mix. I always watered to runoff...when I have actually been more successful in my situation when limiting runoff until after my roots get very well established. During my recent attempts I have been watering until runoff almost from the beginning, because that is what everyone seems to have work for them. Ventilation and lighting is good, but conditions are a bit hot and dry (usually 80-81.5 F and less than 40% humidity...usually around 35% or lower).

I will describe my symptoms. I will preface my observations by saying that I am a fairly experienced gardener (since 05) and have had some successful grows start to finish. Just not in the last 3-4 years (I know...ouch...that is why I suspect bugs. My outdoor veggies have done pretty well during this period.

My plants just seem to never really hit their stride and take off like they should. They would grow, but in starts and fits. They would develop side branching, but not smoothly. I would get what looked like Mg deficiency. Like a creeping Mg deficiency...that once the plants got bigger really seemed to manifest more prominently. My leaves would be really dark green...like too green...perhaps nutrients are not being uptaken consistently and are building up because of incorrect pH. I would get an occasional misshapen leaf...or scarred looking leaf (think DJ short mutant looking...but only on a few leaves...none of which were of Blueberry genetics) on all plants. My plants would always stall after about 1-2 weeks of flower and herm. Bud development would always look 2-3 weeks behind schedule...never finishing...and I would get pissed and pull them after about 6-7 weeks. The plants would never even begin to start "stacking flowers", not even close. Eventually the plants would stop uptaking water...after decent root development in veg (soilless medium. Hempy's were transplanted from rooted seed or clone to full on bucket).

That about sums it up. Thank you for the interest and help guys. Wish I could show pictures. But no grow going on now...just creates too much stress and frustration. More just wondering about the phenomena of pH drift in soilless. And perhaps other pH and watering tips in soilless. Thanks again.

 

[Hammerhead]

PH doesn't drift in soil do the the buffers that are added(Agricultural limestone). I use RO/DI water it always drops over time when its sitting in the rez. you should check if you have hard water.. PH range for growing Cannabis in soil is 6.3-6.8.. Every time I mix a new batch I let it drift, Nutrients uptake better at different PH values. You can see if I always feed at 6.3 they would never get any P. Hope this helps..

 

[ballplayer 2]

My tap water is extremely hard...about 35 grains of hardness. I would only use a mix with 20% tap water and 80% RO. So you feed at 6.8 occasionally to make sure they get some P ? Thank you for your help.

 

[evertking]

Use lime, dolomite lime, powdered. Is your peat promix?

Do yourself a solid and take his advice.

 

[the gnome]

Use lime, dolomite lime, powdered. Is your peat promix?

Do yourself a solid and take his advice.

sage advice up there

peat is naturally acid, i use promix,
even they say it pre-buffered i add a couple tbs per gallon.
i add that to FFOF too.
you can't over shoot past 7ph with dolo.
i add it regardless
Ive used FFOF and after veg, into flower and using chem salt fertz the ph will drop quite a bit.
my 1st run with promix/FFOF mix i didn't add dolo for for the PM,
3-4wks in flower soil Ph was in the mid 4s and plants showed it.
a few tbs top dressed in the contain and all was good in a few 3-4 days

 

[stoned-trout]

it shouldn't..