my aeroponic set-up took me some fine tuning at first but here was what i ended up with. no yellowing, roots in 8 days average.100% success
i used a medium sized pond pump from lowes ( i cant remember the gph as i dont have it anymore, but it was the middle size of three that they carried if that helps) ran two inches of hose from the pump the a pvc assembly, a figure eight with fine mist nozzels placed every three inches, i did not glue this together to keep toxic chemicals out of my tub and to make cleaning and adjusting easy.
that fit into a 15 gal rubbermaid tub with a lid.
30 1.25 inch neoprene pucks sat in the lid.
i had a $10 aquarium heater from wal-mart that heated to 75 degrees then turned of.
i used an aerator with a one foot air stone at all times.
i placed a clear 15gal rubbermaid container on top of this assembly upside down and held it in place with velcro.
i made sure to cut plenty of vent holes in the clear tub for plants to breath.
i cut a hole to mount the t-5 light in the clear tub to suspend it over the plants
the light ran 18 hrs on 6 hrs off
the pump ran 24/7
the heater was on at all times (but only heated to 75 then turned off)
the aerator ran 24/7
i filled the bottom tub with this solution: Reverse Osmosis filtered water (ppm 12-18 ) adjusted to 200 ppm of Canna's Aqua Flores (part A and B), ph 5.5 - 5.8 twice a week.
between feedings i would top the tub off with just plain R/O water and adjust PH to 5.5 -5.8 daily
keep the air around your clones under 80 degrees at all times to keep your clones green and rooting fast.
you should trim the rooting clones daily getting rid of anything that might be dieing this increases success rate drastically
once a week i took all plants out and cleaned every thing with bleach water use a 10% bleach 90%water solution and thoroughly clean everything, scrub pvc, nozzles, hoses, airstones, neoprene, the tub, the heater, air hoses everything. after that clean it again with warm soapy water, then rinse very well with plain water, pay special attention to the airstone. all this is very important to producing good green clones.
i find that you want to keep rockwool cubes and peat pellets a little warmer to get well rooted clones. around 78-80 degrees.
in response to retired toker