Update from my previous post; the longer my newly setup cycle ages, the more HS pockets are forming. You really can’t see the black areas on the substrate surface until you remove decor. I’m in the process of slowly removing a large percentage of the sand and mixing small gravel with it which gives it a more natural appearance. I’m doing it in phases so not to shake up my CLs too much. Thus far I’ve got an approx 60/40 mix with the gravel being the 60 (no more than 1” thickness). I don’t think I’ll eliminate all the pockets from forming but I’m hoping for less.