do you have to wash expanded clay pellets before using?

hello all, I just transplanted 4 seedlings that are two weeks old. they are in 4" rockwool cubes and I put the rockwool into expanded clay pellets inside of mesh pots. When watering, the water that ran off was very dirty, the color of the clay pellets. Was I supposed to wash the clay pellets before putting the rockwool cubes into them? also, when watering, should I concentrate the water into the rockwool? or into the pellets? or a little of both?

please help! THANKS!

YES! You must wash hydroton before using it. Otherwise you get a lot of sediment buildup and it could potentially mess with pH levels.

I just stick mine in an old spaghetti strainer and run it under the sink until there is no color to the water draining out.

Yes. Lots of dust and crap. I throw mine into the bathtub and rinse with water for a while, then onto an old towel for air drying.

It's the same procedure after a grow, except soak them in diluted bleach or hydrogen peroxide first.

thanks guys, much appreciated!