rockwool stays to wet for my likeing,if I use it I only use the 1 1/2 x1 1/2 to put germed seeds in,as soon as I get roots showing out the bottom I put them in 4" or 6" net pots with pea gravel,actually its gravel from a fish tank and it works for me, no hydro stores were im at.I see you have 1 wrapped in insulation,I did the same thing,Im just putting the final touches on a rdwc set up I made myself,I want to have my buckets linked togeather with a res to make things easyer as you will find out when it comes to changing your nute mix and keeping temps in line,also I dont see a water level tube on your bucket,this will let you know where your level should be and also let you know how much the plant is taking in. good luck your off to a good start keep an eye on you nute temps,I lost a plant 1 week from havest because my nutes got to warm.