ebb and flow veg

Well, adjusting the light height will be a little tricky since the mother will eventually be a lot taller than the clones. You'll have to keep the light above the mother. For the clones you could put them on a table with legs (cut from pvc pipe) inside the main tray. PVC is cheap and you can cut whatever length you need.

Personally, instead of 1 mh, I would do a couple sets of T5s (or buy CFLs), one set for the mother and another for the clones. Then you can adjust them independantly. And you won't have the issue of stretching you get with a MH over younger plants.

 

I veg my clones on an ebb and flow table. I start the clones in 4" rockwool cubes and move them to the table when roots show. The table has a layer of hydroton that the roots grow down into. The mothers are in 5 gal pots in pro mix and sit to the side of the table and at a lower level. I hand water the mothers. I have one 1000w MH above them all.
Works well

 

1 drop the hydro pepples more hassle than worth rockwool is best for ebb/flow
ur power goes out for 12 hours kiss ur girls good bye if u do go hp cover top table in bw plastic this will help increase humidty in rootzone if u use just pepples

ur mothers simple train them to grow verticalmines 3 feet tall IF it wasnt trained to grow sideways this increases clone sites leads to much better light disstrbution if using cfl's as they have 2-4 inches of useables light for fast growth

 

Regardless of plant height management, you won't be able to have mothers, clones and flowering plants under the same light schedule. Adding additional hardware will be necessary to have those separate spaces working together, but that shouldn't keep you from getting started with what you've got! The 400MH will be great for mothers and vegging clones, but will be a little under powered for the 4x4 tray (25 watts per sq foot) in the long run. I'd suggest at least a 600w HPS for flowering.

And as painkillerman points out, hydro is not for everyone, but I disagree about it being more hassle than it's worth...and it takes a considerably longer period of time than a 12 hour power loss to kill plants! I pulled a male from my table two days ago, set it on the floor of the garage and it's still in good enough shape to snap back should I decide it needed saving.

As you're getting started, I'd recommend following the ideas of the guy attributed with developing the Lucas Formula feeding schedule (he didn't, but that's not the point). His methods and beliefs are extraordinarily simple and straightforward and really easy to follow. Visit the link in my sig to AskLucas.com for some enlightened reading!

 

Yeah, I think he was saying don't use hydrotron but use rockwool instead. I don't think he was saying don't do hydro. But I agree 12 hours isn't enough to do any harm.

Just to add... started 4 plants from seed a couple weeks ago. Put them in rockwool cubes. Been just emerging them in solution 1x/day by hand for a few seconds. Up to 500ppm veg solution now. Doing this until I get my ebb and flow plumbing setup (hopefully soon). I have to say, never had better looking plants at this age!!! Having done DWC with hydroton before, ebb and flow is a lot easier.