Help to evaluate some run off pH levels

[1984]

Hi. After some ongoing problems - yellowing tips on upper fan leaves, and that then extending to other leaves lower and fresher/newer growth, I decided to flush potted plant following this procedure:

1 Plant (6 days into 12 12) in 7L pot.

1. Flushed with aprox 6L TW at pH 6.83
2. Flushed with aprox 6L DW at pH 6.63
3. Flushed with aprox 1L TW/DW at pH 6.70
4. Flushed/watered with 1L water mix: 1/4 TW, 3/4 DW and 2/3 tbls lemon juice - mix at pH 3.73
5. The first (half liter) run off measurement came in at 5.46
6. The second half liter and final run off came in at 6.58

Question: what do you think is the true soil pH?

Using exact same water mixes (initial pH solutions as per above), I watered and measured the run off to;

Plant 2. pH 4.70
Plant 3. pH 5.25
Plant 4. pH 5.80

What true soil pH do you think these last 3 would actually have? The meter was washed and rinsed with DW, then dried with tissue paper, before each reading. However, going by the increasing pH in each successive watering I suspect these may not be as accurate as the first flushed plant.

Opinions welcome. I'm pretty new at this pH lark so only have half a clue as to what I'm doing.

PS. The plant in question is the one in my gallery, which is there coz I don't have a clue about how to include a pic here in the text. The plant you can see there has yellow tips on 2 levels of fan leaves but is now between 4 and 5 weeks older, pushing 1 meter high, and the fan leaves affected are now at around 7 or 8 levels. New growth includes the yellow tips and is now extending to node growth - before it was only fan leaves.

 

[Koskesh]

since you said potted plant i'll assume you're in soil... why the lemon juice? 3.73 is not something you wanna drop into any medium... that 6.58 runoff is sexy, leave it alone. and relax the nutes/watering a bit

 

[1984]

Why the lemon juice? As a quick fix solution. Sorry, what I didn't mention was that the plant's soil pH had come in at pH 8.3 and I had read here that lemon juice or vinegar brings it down. Based on what I've read if you put a low solution in the soil, say 3 pH and the run off is then say 6, then the soil pH is going to be somewhere in the middle of these 2 numbers. That's how I understand it anyway, could be wrong. As far as I can tell the pH game is a guessing game, and one I'm not good at. Either way I did put in the 3.73 solution and the run off came in at 6.58 so the people that say this must be right up to a point. On the other hand they also say that the lemon juice/vinegar fix is unstable, it won't last.
Thanks for your input Koshesh.

 

[sirgrassalot]

This looks like fun, yeah right! Here's a video on pHing. I've never had to pH anything, thankfully.

http://ganjaguerrilla.net/PH & Flushing.WMV

 

[1984]

That link doesn't go anywhere

 

[sirgrassalot]

That link doesn't go anywhere

Open a new window than copy & paste it into your address bar or go to lower link, find the streaming videos where you'll find the flushing video. I don't think video links go direct from IC, why the link works but not from here.

http://ganjaguerrilla.net

 

[stinkyattic]

Here's another soil/water chemistry link. It's got a lot of info, and I think it's written pretty straightforward:
http://boards.cannabis.com/plant-pr...-ph-flushing-correct-lockouts-why-how-do.html

Flushing with distilled or RO water will give you a pretty accurate read-out, since by definition, the ionic strength of those types of water is so low that any change in the pH that you see coming out of the drain holes is going to reflect actual soil pH better than a 'harder' water.