Quote Originally Posted by Photo Engineer View Post
Just measure the pH and be reassured that if you adjust it to where you want it to be, things should work out.
Ron, Then that's what I'll do. I picked up the pH meter today.

The formula I posted recently has a pH of 8.05. The test-strips said 7.8-7.9. You were right: They're significantly off.

Quote Originally Posted by Photo Engineer View Post
Don't forget the toxicity of Boron containing salts to Citrus plants. IDK where you are located, but some of these salts are restricted in CA and FL.
With that encouragement, I decided to try removing the borate. The sulfite becomes the sole alkali, and I added ascorbic acid until the pH dropped to 8.0. Without the PG, here's the resulting simple 1-liter formula:

Sodium sulfite ................ 90 g
Phenidone ..................... 0.15 g
Ascorbic acid ................. 3.5 g
Target pH = 8.0. 7.5 min for TMY at 20C.
That's it! And with a brief exam, I can't tell the difference between this formula and XTOL. I'm surprised. Has anyone before tried this simple PC-plus-sulfite formula?

Mark Overton