Ideally, coco should not need a dry / wet cycle like a dirt grow. When it drys out your ppms and ph can get out of whack, it should be thought of more as low tech hydroponics. That said, I totally understand why people have to let their coco dry up a bit between waterings......
The problem is, there are so many inferior brands of coco on the market and - just varying properties that each brand has to be learned on its poristity.
Of course, the best stuff will have decent porisity and can be kept moist (not water logged) 100% of the time. But most brands I have bought will need some 'help'. With
grotek blocks, I use 50% perlite, and hydroton at the bottom. It works great, plants grow fast but I have needed a constant drip.
Another big mistake people make is they dont squeeze the water from it and put it into the pot 'fluffy', and then they end up with a low oxygen water logged hell. ----then its actually easier to over water than
promix!!
I keep hearing people say you dont need to rinse coco anymore but all the coco I have bought has had insane ppm run off and so I put it in a burlap sack and rinse the hell out of it. Its unreal what comes out. I have noticed a real difference in my plants ever since I have made these changes.