Hi, im havong issues with rust spot. Im in Mother Earth coco/perlite. Was using fox farm trio. 18/6 and ph 5.7-6.0. Ive tried giving extra calmag no reslove. I did a run off test and the ph was 6.8 and 800 ppm. Flushed with 15 gals each and feed normally to no reslove. It seems to be progressing...