soil soil runnoff ph too low?

I watered until I got about a half inch of run off in the drip trays to make sure they got a good soak again. I normally only water 2-4 cups of water every 3-4 days, now that the plants are getting bigger I figured its time to water deeper, especially since the Thais are showing some curling on then leaf edges.

The pH of the water going in is 7.7, the runoff tested at 6.2. Which if I understand correctly would put the soil pH around 5.5. That could mean some nutrient lockout of cal/mag and phosphorus, and a slight reduction in nitrogen uptake.

The plants are in 3 gallon grow bags with miracle gro potting mix with a bit of bonemeal added, and some myko's added during transplant besides a tiny bit of mykos added to the seed starting mx. The potting mix is supposed to be 6.5 to start with, and the bonemeal should raise the pH, not to mention the higher pH of our well water, I'm sorta confused why its testing so low unless the plants already ate up that much of the fertilizer.

Should I top dress something to raise the ph or start using a pH adjusted liquid fert?

I would do a slurry test with the water at pH 7.0

I took a sample from the top inch of soil and mixed with equal amounts of distilled water. PH came out at 7.9. That may not be the most representative coming from the surface rather than closer to the root zone, but kind of afraid to disturb the roots. I even double checked calibration, meter was right on.

After doing some further research, I found some information on peat based soiless mixes. The peat is quite acidic, so they add pH high slow release granular fertilizers to counter it. When you test the runoff, it tends to be quite low since the peat affects the water pH much faster than the slow release ferts do. Hence the reading I got. As long as the runoff pH is above 5, it should be ok according to the article I found. Another example of the differences between peat mix, soil, and coco.

I know that a lot of us (growers) tend to be very active in our approach to our grows. We like to tinker and test, tweak and try out new things. You seem to be one of those types !!
 
That said, sometimes the best advise is to just let things alone and let nature do its thing. Personally, I wouldn't worry about the runoff pH, unless you have some serious problems with your plants... like major nutrient deficiencies. Even in that case, you could simply flush the soil with RO/distilled water to wash out the excess. If a good flush doesn't work, well I'd say that you have some epic problems with your growing conditions... and testing the runoff isn't going to help you.
 
But hey, if your just curious and want to learn more about soil... then test away !!!
 
Jeff 
 
 
 
 

I don't use coco or peat because of this....yes it's great but I get better results sticking with a premium potting soil with out coco or peat base or as little as possible.
 
My water is 7.2 out of the tap....The soil is a natural buffer, no need to rethink the wheel.
My nutes automatically drop my ph to 6.2 - 6.5 
 
as long as you are in that area, your soil should be fine.
 
Try cutting your nutes in half at each watering and forget about trying to ph your run off if you're really that concerned.
 
I only get concerned about ph in DWC and similar growing practices without soil.
 
Good luck