Strange PH problem - first grow

[stokesy]

I'm using rainwater, ph 7.26. In order to take it down to 6.3 (soil), I've tried adding ph down, bought from an aquatic supply shop.

I have 20 litres (5.25 US Gallons) in the watering bin, I also have nutrient in the mix, 8-2-6 npk (Bio Grow) as I'm deficient in Nitrogen right now...

Problem is, that adding the ph down, reduces the ph to 6.99.. adding more, RAISES the ph! It also increases the EC from 1.00 to 1.4.

I've tried small test runs, using say, 1/4 pint of rainwater, no nutrients, and the same thing happens. The ph lowers a bit, and then adding more, increases the ph.

I've checked the ph meter, and it seems to be ok... (checked it using Milk of Magnesia, AND buffer solution, and both are almost spot on).

I've just tried substituting fresh lemon juice, and that seems to do the job.. don't have the facilities to check it with the full 20Litres right now, but that seems to be the way forward.

Can't figure out why the ph reverses after a certain amount..

Anyone have any experience of this?

Thanks!

 

[BWC BayArea]

Never heard of anything like it. You ever get to the root of the PH fluctuations?

 

[stokesy]

Never did, with the ph powder adjustments. Just used lemon juice - that was ok. However, I did have a major problem keeping the ph down.Watering with water at 6.00 - the runoff would inevitably be over 7.00. Soil I was using (Biobizz Allmix) was too rich in nutrients to start with, in my opinion. Second grow, I'm using Biobizz Light. That seems to be working a lot better, ph wise.

Thanks!

 

[jammie]

hey there stokesy- i use rainwater exclusively in my 5 gal dwc. my ph starts a little lower, usually 6.4ish, after adding nutes it drops to 4.9. a couple of drops of liquid silicon brings the ph back up to 5.8. it usually stays stable for 4-5 days. different nute companies use different quality buffers in their fertilizers. i use ionic because its so stable

 

[stokesy]

Now on my second grow, and still having the same problems.

6 plants, PPP, Northern Lights, AK-48, in Biobizz Light soil, mixed with perlite. Using Biobizz nutrients - Bloom, Grow, and Top Max. In the 8th. week of flowering, and watering with adjusted water + noots, at around 4 - 4.,5 ph, the runoff is 7.5 or so. completely flushed each 3 gal container about 10 times and eventually got down to 7.0 - still too high, but I ran out of time.
Since the flushing, I've got sever cupping of some of the leaves, which may be due to heat - but the heat is the same as it always is - 75 plus or minus 5..The cupping I think, is a separate problem from the ph problem...
Using lemon juice as a ph down.
Seems odd to me that the ph runs high - most people seem to have the reverse problem..
Anyone tell me what the problem is here?

Thanks!

 

[3apata]

Hey, I am having the same problem, mate! Only difference is I am not using BioBizz soil, only nutes - Bloom, Grow and Algamic. My soil is rich in nutes - the worm castings, I guess - so they grow fast, and I can't bring the pH below 7. Not even if I flush a 1 litre pot with 4 litres of water. I get to the point that water starts passing much more slowly through the pot, when flushing - saturation, I guess....

 

[willoby]

How long do you let it sit before testing the Ph??

 

[stokesy]

Me? I've tested the first runoff, and the final runoff. It seems to me, if the soil is a bit dry, the if you just blast 2 or 3 gallons in there, then the first ph runoff will be mainly that of the water. - due to the water passing through the cracks, air holes, etc...(This contradicts most of the theory I've read). So - I go by the LAST r1unoff. Seems to me this makes more sense. But of course, i'm open to learn differently...

 

[3apata]

Hey mate,

He means the nutrient solution, after you mix in the nutes and before you test it's pH and begin correcting it. I've read that sometimes it takes up to 40 minutes to stabilize. In my case it showed no changes over time the first time I checked it, so I stopped waiting that long. But I guess repeating those tests is a good idea, especially now that I've started using different water (RO).

Before watering or flushing, it is recommended that you cultivate the top layer of the soil in your pots - break it up with your fingers or with a fork. Careful not to harm the roots that are close to the surface. This will prevent the water from running through your soil without interacting with it, which is undesirable. Having done that, you should give the plant about 25% of the total quantity of water you intend to give it (like, I give 2 pints to a plant that's in a 3 gallon pot) and wait for 15 mins. I repeat it again after that. In addition to preventing 'run-through', it will also allow the stuff in the soil to dissolve and be flushed out or leached out.

3>

 

[stokesy]

Ahh,...! Nutrients... ok, Ill check this next time. In a few days.

Tks!

 

[Captain Kronic]

I tell ya what... maybe you got some funky PH down?

It should not be affecting your electrical conductivity, as far as I know!
If the PH down you are using is Nitric Acid... it will raise your EC. Get the phosphoric acid type and try it then... let us know how it turns out for ya... ciao baby!

 

[3apata]

Anything that gets dissolved in water affects the EC. Well, not everything, but even the substances that don't will raise the TDS level, and that's what's important, AFAIK. I am guessing that a stronger acid will achieve the same results pH-wise with a smaller increase to the TDS level.

But what about the pH?