Help me to understand PH and coco coir soil.

hey all,

I've decided to take control of my PH and have bought myself a bottle each of PH Up / PH Down and a nice digital tester.

I use tap water and let it sit in 2 Litre Coke bottle for at least 24-48hrs. At the moment i'm not adding nutes so it's just plain water that comes out at around 6.5 - 7 PH.

I had recently germinated some seeds in rockwool and i gave them PH 6.0 water and let them go until they had roots. I've since transplanted the rockwool cubes into 1 gal pots and i am using coco coir as my soil.

I need to understand if i am maintaining the correct level PH for use with coco coir.

i have read that when using coco coir you would need your water at about 5.8 PH but i also learned that you should be testing your run off and that your runoff should be in your target range required.

I had to flush one of the plants so i set my water to 5.4PH, flushed with 2 litres of water and tested the runoff and it was 6.8. i believe this is too high??

anyway, going on instinct, i decided to flush the plant again today and set my water to 5.0PH and flushed with 4 Litres of water. this flush seemed to be better as the water was very dirty after the first 1-3 litres and quite clean when i tested the final litre of runoff. i tested twice during the flush. but anyway, the runoff looked much cleaner and the PH was 6.3.

6.3 is a bit better than the previous result.

what i really need to know is, am i on the right track with the way i'm doing things? e.g. lowering the PH substantially more than i think i would have to so that my runoff is in the required target PH range.

and...

my next watering i am thinking of lowering the PH to 4.8 or really it should be 4.6... is this an alarmingly low PH level to water your plants with?

it seems 4.6 will put my runoff at 5.8 which is apparently ideal for coco coir.

if anyone can offer some helpful advice that would be greatly appreciated.

thx for reading.

remember when flushing that proper P.H. and a to use a mild dose of nutes so you dont leach out all your nutes with clean water only.. 5.7 - 6.3 is in the ideal range for P.H.

thx walli. i'll remember that thx.

anyone got anything to add ??

i used 4.5 to water and killed 2 plants...stunted 4 more.. totaly ravaged my garden.... be careful with such low ph... way acidic! tryin to figure this stuff out also. im in coco as well

good luck, i've subscribed.

im interested to find out as well as i have never used coco but am about to try it.

i would assume though that you might have misunderstood what that person was telling you about the runoff being in the ideal ph range. I think what they may have meant was to make sure to test your runoff to make sure your root zone is in the ideal ph range. the median between your water ph and runoff ph would be the root zone ph from what I understand. So if you were watering at 5.0 and runoff was 6.3 your root ph would be 5.7 which is about perfect.
and if you did find yourself with a very high runoff ph you would probly want to bring it down over a couple of waterings.

Again, thats just from what I understand so dont take it to the bank just yet lol.

anyone able to clear this up?

mossad420, i have heard as well to lower the extremely high ph slowly over a couple of waterings. also you brought up something that i had not thought of with the ph run off being the median, this makes sense to me. although i still would like to know for sure all this ph stuff.

do we have any experts with ph and coco here that KNOW this for sure? im sure we do, we just need them to chime in.

i really need to find out this info too guys, i think my pH is too high as my jack herers and jock horrors have seemed a bit slow. they are flowering now and i have just got my ph up/down so i'm trying to figure this out. i think i need a digita ph meter though hmm... i have got a liquid indicator test , is this accurate enough?