Quick Question: (I've tried searching)

Smaller the better as you don't want it to be your main medium for more than 2 weeks. You'll veg the rest of the time in the buckets.

I like the 40mm sized grodan brand. It holds enough moisture so that I have to check/water once a day and its not so huge that it takes forever to fill it up with roots.

1x1 or 1.5x1.5 R/W cubes are all you need for seed starting then place rooted cube in medium of choice(ie Hydroton in net pots).
Warning:R/W can easily be oversaturated,you want moist so shake off excess and do not squeeze.What I do personaly is remove wrapper (each cube) and soak ph corrected water (no nutes) 5.5-6.0 for half hour.Drain and soak an additional 15 minutes in fresh solution.Then remove and give about 15 shakes/flicks of the wrist till no more drops of water comes out for each cube.Then I take a sterile razor blade and cut a slit 1/2" deep opposite end of preformed hole.I place a seed in middle of slit on it's side 1/4" deep then rip a small piece of corner and very gently/lightly pack over slit.Cubes are kept in humididome (for moisture retention only) at 75F-80F (80-90F faster germ but higher risk of seedling fizzle) till sprouted then placed in medium of choice (healthy sprouted seedlings do not need a dome) with PROPER temps,light intensity and 1/8th strength (ph 6.0) nutes keep cube lightly moist till roots take hold.
Most people will keep sprouts in dome till fully rooted leaving dome 1/4-1/2 open to harden them off.#1 problem is cube oversaturation inwich chokes out taproot of oxygen.I shake off excess and gently press cube on top of wrist for a tiny beeds of sweat look.Youtube:Grodan 101
know before you grow.

Yea I use 1.5 inches work good for me in 3.75 net pots.

ive used 4" rw blocks with no problem. i had to veg in them for a couple weeks so it made sense. just lay a layer of hydroton in your net pot (i use 6in pots btw) then set you cube on top and fill it in.

You dont even need RW if you startes your cuttings in an aero or bubble cloner.

Originally Posted by Shivaskunk

You dont even need RW if you startes your cuttings in an aero or bubble cloner.

Yeah I was thinking of that also, but I've never used net pots and it seems like it'd be a real pain in the ass to situate bare roots inthere, right? Would the hydroton just have to be more moist until the roots creep into the water? Sorry for the Q's, but I'm making the transition to hydro haha

you can make the holes a bit bigger to pull the roots through. If the roots are not long enough to reach the water yet just keep the water level right at the bottom of the netpot until roots drop ito the water.

Just say no to rockwool!!