You may not be getting much dumping because you top-dressed the CRF into the buckets, and the top 2-3" of the perlite stays a lot drier than farther down.
It may well be that your flushes are giving them what they need, not taking it away.
It's pretty damn hard to overwater a hempy. Why not try smaller flushes more often and see how it goes?
If your temps are high though, it would cause evaporation in the perlite to increase leaving the medium to dry to create an environment for osmosis like SS mentioned. Either way more water = better results so the heck with it.
good points!! i will have to try this and water every day and not only every 2 days. i do have SunShine #4 mix in the buckets, so it dose stay moist. but i see what ur saying since i only toped dressed them they not staying as cool or moist as they would mixed into the medium.. makes sense to me..