Hi friend
It depends how much they are drinking
My advice is that with coco don't treat it like soil coco should be watering more regularly than soil what size pot are you using? Why i ask is people make a very common mistake with coco they treat it like soil with coco you dont really want it to dry out I would say what your doing is nearly correct but I imagine you were feeding to much one time the way I think coco should be fed is say your using a 16litre pot and plants big drinking fast in veg feed 400ml 5 times over the18 hours if they are drying out before the 3 hours between feeding up400 to 500 start as soon as lights on and feed just before lights off they drink very slowly in dark so that little will hold them. in bloom the plants are going to drink more but think over the 12 hours light every 2 hours hit them with 500 ml if they dry in-between feeds up the feeds 600 or 700 with cocoyou don't want totally dry ever like you would with soil it will make you work coco's coco wants small pot 5-7 feeds per day and I think soil bigger pot and every 2 day feeding i hope your OK with my answer im going to follow you and please follow me let's share the knowledge and experience and become π