First I HATE Rockwool. I never use it because I hate that crap.

Ok....my hydro systems are 100% grow rocks or lava rocks they are 2 different things.

I run my drippers 24/7 no emitters full open. Grow rocks don't hold water for longer then a few hours. It's just a 1/4" drip line with a 526gph pump driving them all so I just let it run.

I clean my rocks in between each grow and I use a small cement mixer I got from Harbor freight tools for 130 bucks. You drill a shit load of holes like 3/8" all over the tub for drainage but it makes it easy to clean them that way.

I don't throw them away, sometime they get to small and fall through the holes in the mixer but that's about it. They don't ware out or anything if you keep them clean then they will last years.

You can make one with a 5 gallon bucket full of holes. Fill it about 1/2 way with grow rocks put the lid on. Lay it down and roll it around the yard for about 5 min or so wash it some more and do it again until they are clean. If you want to sterilize them and sometime I do. I have a turkey fryer and just fill it with water and boil them.

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