pH runoff is lower than the pH of the medium

[stinkbudd]

I placed a few seeds in some Canadian Sphagnum Peatmoss mixed with perlite. After I poured some neutral RO water through it to wet it, I tested the soil with two seperate rapidtesters and both showed pH of 6.8. The runoff, I tested with my hanna tester (which is calibrated and accurate) tested at 4.9 pH. It's been 36 hours since I did the test and the seeds did sprout but I'm not sure what my pH is. Or what it should be since I am growing them in a soilless medium.

stinkbudd Reviewed by stinkbudd on 01-06-2007. pH runoff is lower than the pH of the medium I placed a few seeds in some Canadian Sphagnum Peatmoss mixed with perlite. After I poured some neutral RO water through it to wet it, I tested the soil with two seperate rapidtesters and both showed pH of 6.8. The runoff, I tested with my hanna tester (which is calibrated and accurate) tested at 4.9 pH. It's been 36 hours since I did the test and the seeds did sprout but I'm not sure what my pH is. Or what it should be since I am growing them in a soilless medium. Rating: 5

[mc-blaze21]

soilless mediums should be a ph of about 5.5 hope that help's u can also read kp's cannabis collage at the top of the thread list it has every thing in there you will ever really need laters peace!

[dutch.lover]

i think the runoff water you tested would be more accurate than testing the soil itself. just my two cents, but i think you need to raise the pH.

[stinkbudd]

I experimented with a sample of some peat moss. I ran some RO water with a pH of 8.3 and the run-off came out at 5.6. So given that, from now on when I water it with a pH of 8.3 will that be sufficient? Will the peat moss' pH be permately changed or do I have to continally water with a high pH?

[stinkyattic]

Hey sup[ stinkbudd you have a major problem.

This is what you need to do:

THROW AWAY YOUR MEDIUM!!!!!! Peat moss has a pH around 4.5, and that is a guaranteed KILLER. Take it from me... I've killed an entire crop trying to be cheap and use some leftover peat moss from my outdoor gardening activities for a soil amendment... it's nasty stuff.

Now I'm a bit confused, how does your RO water have pH of 8? That makes no sense! Pure water with atmosheric gases dissolved in it should show a pH just BELOW 7... from the carbonic acid...

The reason your runoff os so low is that the water is reacting chemically with whatever is in the soil, and some of the natural acids in the peat are leaching out into the water as it goes through, and it's just a big mess... you want to start with a medium that is not only already at your desired ph, but is BUFFERED there. I have said this a million times if I've said it once, there's an easy way to guarantee NO ph probs ever, and that's to use a mix that includes a shitload of nice decomposed leaf humus.

On the up side, you are checking your pH correctly using the runoff method.

[stinkbudd]

Now I'm a bit confused, how does your RO water have pH of 8? That makes no sense

I used pH UP to make my RO water higher ( I guess I should have said that in the beginning)

I really want to try a soilless organic medium but not go totally hydro. I remixed my peatmoss/perlite mix with some lime today (about a teaspoon per quart). If my plants show some problems due to the pH, I'll switch to some coco based medium (if I can find it) unless someone could suggest another good soilless mix