Hey guys

I have recently started my first hydroponic grow. I have attached pics. I started my seeds in rock-wool and have since potted them in clay pebbles. In hindsight i think i should have started them in clay pebbles in an aerocloner. I used to have them above the clay pebbles and have since buried them deeper to cover the rock-wool. I think my setup is technically a drip system? I have been watering 8 times a day at 1 min intervals (only when the light is on). My question is can i run it more? I'm worried about root rot because of the rock-wool?

Also i am using a 400W HPS and MH combo for my grow. My tent is 800mm x 800mm x 1600mm I recently bought a 300W full spectrum LED (link below) Will it do the job and can i swap it out now?

http://www.ebay.com.au/itm/311635510040?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


Any tips and advise is appreciated!