i have been correcting our rainwater ph to 6.9 all season and the girls have started showing distress. on a hunch i flushed the soil with 8.1 ph water from the rain tote last evening. the run off was 5.1ph. i have been feeding on the low end and cal mag also again on the low end. The same thing happened last year but we weren't as attentive to the ph. i suspect the rain water has little to no buffer and as a result ph can fluctuate like in a koi pond. does anyone have knowledge of a buffer (not for koi ponds) that can be added? would a good flushing 2 or 3 time a season be in order? for now i will keep watering at an elevated ph and monitor the run off. thanks every one and look forward to finding out more about the process