Hi, When 'new' I just rinse the dust off the expanded clay (hydroton) and use it as is no worries. When I recycle it though I rinse it and use a dilute bleach solution to sterilize them in, Then I rinse again and use the washed ones over and over. Note of caution, always let your clay pebbles air dry before storing them otherwise molds may still strike.
The way I've been working my hydroponic system is this: made a mother from seed to take clones off of. I would use one of your feminized seed starts for this, it'll give you the strongest possible cloning energy. Clones are rooted in 3" rockwool cubes (they provide stability in the clay pebbles) for 2 weeks under a dome until roots start to show. Clones get transplanted into 6" 'Emily' pots with expanded clay, leaving a half inch of rockwool cube exposed to prevent crown rot and stunted growth. I use top watering drip system with adjustable 180 degree 1/4 inch threaded sprays connected to algae resistant 1/4 inch tubing on a stake.(you can turn them off and direct the stream) This works easiest for me especially when moving things around.
Watering depends on how fast the planting medium dries, how big the plants are and the type of lights you're using. Expanded clay dries pretty quickly. I've had good results watering 6 times a day, under a 400watt HPS light, your pattern may vary. Main thing is watch your plants they'll let you know what they like.
Sorry I don't know what an arrow dripper is...main thing is get water to the roots whatever way you can and as thoroughly as you can, bigger roots = healthier plant & bigger buds.
Hope this helps, Happy gardening! GrowIT!
