Pretty obvious to see the Coco is too acidic and the Girls have locked out.
Now the next problem..... my equipment.
I have a Bluelab Guardian, a Bluelab EC Truncheon and also their pH pen....all about 6 years old, except the pH pen which is 3 yrs old.
As I said in post 1 of this thread, the Guardian's pH pen is out of action.... I haven't pulled my finger out and sent the whole unit back to Bluelab in NZ.
The reason why.... I still use the EC bit. My Truncheon gives a lower reading, so I only use that for mixing.... an expensive mixing rod!
The pH pen, well I had to calibrate it on Wednesday... it wasn't far off, so I think the pH's are reliable.
Then I remembered, I have some Bluelab 2.77EC conductivity solution..... yep the Guardian is spot on and the Truncheon is EC 2.3. As far as I'm aware, it's uncalibrateable.
Back to the tests...
Later on Wednesday, at 7.00pm I did a plain water flush... it was pH 5.9 straight out of the bucket, so I didn't bother fiddling around with pH down to get it to pH 5.8.
Water temp 27°C Tent temp 29°C RH 74%
I gave them 5 Litres each, standing by with the big 50ml syringe to catch the first 250ml and an aquavac for the rest of the run off.
Here's the run off details..... not good......
- Des Frans pH 4.8, EC 1.5, 27°C
- Gorilla pH 4.4, EC 1.5, 28°C
- PAK2 pH 4.6, EC 1.8, 27°C
- PAK1 pH 4.5, EC 2.2, 28°C
As you can see, at my current pH nothing is being absorbed.
I decided to fix this by re-alkanising the medium.... it has to be a gradual process without stressing the plants out. The idea is to increase the pH of my feed by 0.5 every day until the run off becomes pH 6.3.
So on Thursday, I made up a strong Sodium Bicarbonate solution. I got a litre of my usual EC 0 base rainwater, heated it up and dissolved as much Sodium Bicarbonate (Baking soda) as possible to make a supersaturated 'Molar' Bicarb solution.
I managed to get the pH of the Molar solution up to pH 7.9. I asked the eminent Scientists at Google, and they reckon the pH of a freshly mixed Molar Bicarb solution should be around pH 8.3, so I wouldn't be able to get it much higher than that.
I also made up 40L of an EC 0.8 pH 5.8 feed, got it to pH 6.3 (using the Molar solution as a pH up).
I gave them 6 Litres each, and here's the run off details...
- Des Fran pH 5.0 , EC 1.2, 29°C
- Gorilla pH 4.9, EC 1.2, 29°C.
- PAK2 pH 5.1, EC 1.7, 30°C
- PAK1 pH 4.7, EC 1.9, 30°C
So it looks like the pH is rising, and the EC is dropping. Woo Hoo!
Visually, there was no change, obviously. This was the first pH adjustment, so there's a long way to go yet, but at least they are heading in the right direction!
Last night I gave them the same EC 0.8 feed as the night before, with a bit more of the Bicarb solution to make it pH 6.8.
Here's the run off data....
- Des Frans pH 5.6, EC 1.2 32°C
- Gorilla pH 4.9, EC 1.2, 32°C
- PAK2 pH 5.1, EC 1.2, 32°C
- PAK1 pH 5.3, EC 1.5, 32°C
The PAKs continue to look very healthy and green, but the DF and Gorilla look much the same, if anything the DF looks worse.
Still, the data for the DF looks the most promising, the pH is rising the quickest, and the EC's are dropping for all of them.