Please some advice needed...........First DWC grow

Got a few THC Bomb (indica/sativa) growing in Fox Farm nutes ( 5 gal.bucket dwc , 7inch net pots ) I got two 4inch flat round air stones in each bucket but as you can see in the pics, on all net pots, the roots seem to only be growing a lot more on one side than the other.... ? don't know why???? I have even turned them around.

I check the PH every two days and kept at 5.8 - 6.0. I change out water every 7 days. I am using Fox Farm's feed schedule which I have cut it back 1/4 percent from the start per gallon.
Growing indoors with four 6500k daylight 42/200watt bulbs running 18/6hrs, 2800 Lumens each.
The stems are almost as thick as pencils and leaves feel thick/stiff...But there all dropping downward but they are stiff and hard. The one plant that I used for the pics has had one of its leaf near the bottom, yellowing tip/not brown and hasn't changed any since the last two weeks. I don't think the leaves should been downward, right?????
And here's the main kicker. these plants are 35 days old and are only 1 3/4 inches tall - that's slow as hell isn't it???? and the cotyledon leaves haven't even fallen off yet..????
Any ideas of whats possibly going on here .... am I forgetting something .....? Thanks folks for some feed back.

OH, and one more thing that might be help ... the roots seems to have lots of moisture but only one or two single roots have actually touched into the water for the last 12 days. I thought that maybe since these roots are now in the water the plants will take off, but there not growing much taller just the foliage getting larger/ wider leaves only...?

im no expert but I would try raising the water level to where a couple inches of the pot are in the water. you have plenty of air going threw the water so aeration shouldn't be a problem. im sure others will chime in soon so don't go only on what I say but im having pretty good growth with it partly submerged pots

As Vida says, start with the bottom of the net pot 1" below water line.
Once roots are coming out all over the bottom of the net pot lower water level so roots hang in the water but the net pot sits Just above the water.

As long as you understand the air stone is in the bucket to create turbulence not to add oxygen then One stone in a DWC bucket should good.

Stunted form overfeeding.
Don't give ANY nutrients for the first week.
Once you stunt em, it takes forever for them to recover.

My .02.
Peace.
Tav