Had to fly to OK this week and leave the plants to take care of themselves. When I got back the poor THCB was looking even worse. A couple of lower branches off the main stalk had died completely, all the leaves were limp like I hadn't watered it in days. If it hadn't been after midnight when I got home, I probably would have tossed the whole plant, but decided to wait a day, and maybe try flushing one more time.
Last night I started flushing, and checked run off PH. I hadn't checked it in the past because I always watered with PH 6.0 water with nothing but a little cal-mag. I expected it to be pretty close to 6, so was surprised to see 4.4 on the PH meter! I got my back up meter which read 4.3. I guess the MG soil was even worse than I had thought. This was the forth, I think, flushing since I up-potted from 5 to 10 gallons and used that awful MG soil.
I flushed the 10 gallon pot with 12 5 gallon buckets of PH 7.0 hose water. I pumped the run off out as fast as I could, but by the end there was water all over the floor and I was soaked from slipping and falling twice. I got the PH up to 5.7, but after that it wouldn't budge. I'll give it a week, and if there's is some recovery I will try flushing again.
This morning I watered all the flowering plants to run off, and checked PH. These all have some of the new soil, but mixed at least 50/50 with the soil I had left over from the spring. The lowest PH was 5.8, but there is still some leaf damage on all of the plants that looks similar but not as severe as the damage to the THCB. I'm thinking they need to be flushed as well, but they are too big to move at this point. I will have to figure out a better method that doesn't end with water all over the floor.
It's hard to believe how much damage a couple of bags of potting soil caused. I still have an unopened 50 qt bag that went in the trash this morning. It makes me wonder about similar issues I've had in the past that might have been caused by inconsistant soil mixes. Next grow will be all hydro, or at least coco-perlite.