Water Changes, Rockwool and germinaten!

I hopefully will be growing White Rhino and Big Bud in a 8 plant EBB and Flow system. From the net pots to the glass they will have 2 feet of growing space. 10 inches above the pots will be some poultry wire for a SOG. I have 2 55 watt Compact Flouresent Coral Life bulbs 3 35 watt floursent bulbs and a 400 watt HPS bulb in a closed off light box with glass. 6 80 MM fans and an OZONE Generator.

I have a few questions:

I have PH strips just incase, but my plan is to buy 30 1 gallon spring water and pre mix my nutes in them according to a scedule I made out. Also having back ups for evaporation and what not.

If I weekly do a water change and with my plant nutes, also while adding the water that evaporates weekly will I have an major PH fluxs? i am an experianced saltwater aquarist and understand the importance of PH and what not. I know it is slightly wasteful to do water changes but if I do them weekly and consistantly I forsee that i should not have any problem with the PH. Keeping in mind I mix the nutes right and am consistant with the water changes.

Also can I make plugs out of normal rock wool and insert them into the bigger slabs once I see roots protruding from the small plug. When should i begin my flood and drain on the plant and for how long each day? since rockwool holds so much water.

Thanks

 

Thanks yeah I plan on just doing water changes i know that with my salt tank if I keep up with water changes I never have to worrie about anything.

I am hoping that with the inclosed light I can keep my room in the 80's hopefully.