what should i feed my plant

didnt realise that rookwool was so hard, dont wanna run before i can walk. I was after the EC/PH testers there about £10 each or about $20 off ebay local to my area. 90% of my kit is home made, i was gonna use and ebb and flow system on a timer to feed my plants and have clay pellets in the base of my pots so the water would run off quickly without the soil filtering throught blocking my pipes and pump 'see pic attached'.

Oh you are going to use the RW as starter plugs only and do the actual grow in HYDROTON.
It's super easy. Run your Cannazyme with your nutes and take what they say about pre-soaking the pebbles and RW to pH 5.8 SERIOUSLY!!!!!

cheers for the advise fella, all noted and taken on board. ded excited for my first proper grow.