First problem; stop taking advice from soil growers. You're not growing in soil, so their practices don't apply to you.
Second, you don't flush coco grown plants....ever. So stop.
Third, you don't water coco grown plants with plain water...ever. So stop.
Fourth, you need to manage your pH @ 5.8...always. So do it.
Fifth, you need to get a handle on your nutrients. Coco plants need to be fed daily...always. So do it.
If you'll follow those simple little rules, your experience in coco will be what you hoped for. Don't, and it most likely won't. Good luck friend.