Hey Rasta,
Used to be a long-time aeroponic grower, in fact, held a petty patent on an aeroponic design for a few years. A few points to keep in mind when designing a unit:
1. keep it simple, the less things to go wrong the better -- and yes, micro sprayers will get clogged if you don't use adequate filters on your power head.
2. Use smallest diameter tube you can get away with (helps to keep psi in the system high).
3. Most important consideration is not lph of your power head but how high it can lift water, obviously the higher the better.
4. You must consider the root chamber as two strata -- the net pot (especially before roots come through) and the exposed root mass. To that end you should have a direct flow to the pot that you can switch off once roots hit the bottom of the root chamber. Use largest orbital sprayers you can find to sprinkle the root mass once roots are well developed.
5. Run the pump 24/7 and rig a drain system that retains at least an inch of water at the root chamber bottom -- yes you will get a power outtage sometime and this will save your crop!
6. Rig a ball valve on your reservoir to keep water levels in it constant -- aeroponics, properly designed, allow your plants to breathe like nothing else and assuming you have adequate light and ventilation your plants will DRINK like nothing you've seen, so keep reservoirs constant.
No, you won't need to do res changes any more often than other systems (less in fact). Your pH tends to be more stable. Don't use too many organic additives that can clog the system. And though it can be a fiddly business over a large scale, the rewards more than compensate. Honestly man, I've used every hydro system there is (and some only now starting to gain popularity -- the vertical setups the Chinese are playing with) and nothing beats a proper well sorted aeroponic setup -- not DWC, not flood and drain, rockwool, not NFT -- absolutely nothing! But watch out, if shit goes wrong it'll go wrong so quick it'll make your head spin--!!
