tinytoon,
I've been reading along with this thread with no idea what's going wrong, so no comment so far. But the difference between 23 watts and 100watts may be part of the key. I totally agree with DH, IMHO they need more light.
I ususally have my Ph around 5.4 and ppm around 350(Milwaukee) when I start to convert from coco pot to net/DWC. I wait until the roots start to run up a 6" pot then transfer them to the 6" net in 5 Gal DWC. The level is 1/4 to 1/2 " until they start to take off, then let it drop down to as much as 4-6" before refilling the rez. I let the ph sweep from 5.4 ish to around 6.2 ish then replace, usually every 2-3 weeks. I Increase the ppm gradually and back off at the first sign of over nuts.

7 weeks and they look like this:

[attachment=o231904]

Laughing Buddha roots...

My :twocents:
M.P.