whooo now a straight up 6.0 ph is way to low, i can get away with 6.0 in my coco but i usually run right at 5.7-8, man id say theres a culprit right there...at min you should be at 6.4-5 but since youve had probs with low ph id say you need to go arround 6.8 or straight up 7 with a heavy flush...