Have you considered starting in a small pot and upsizing as needed? I also like runoff in my soilless grow to avoid salt buildup, but I start with a solo cup and work my way up to whatever size I determine I'm going to flower in. I do stop transplanting once my plants are flowering though, so I pick whatever size, transplant, give them a week or so recovery time then flip to flower.
I had thought that fast version means autoflower when I had planted this. So I did not want to transplanting at all if it was an autoflower. This is why i planted in 5 gal bucket and I only found out yesterday that fast version means F1 hybrid witch is a fast flowering photoperiod
It has been in 5 gal bucket for 2 weeks now so I suppose I will just keep it in this bucket until finished.
Although my PPM/ex meter just came in yesterday and my ppm input on the fertilizer I was using was 1300 and run off was 2500
At this stage I read it should be 600-900 range. Going in and a little higher coming out.
I do believe that this is why growth was stunted
and this is what I did to fix
The runoff was 2500 ppm (way to high) I was not diluting solution before feeding. Just using growing chart.
So I flushed all water in bucket until runoff was 600ppm
Then I waited until next feeding time and add the genral hydroponics fertilized diluted to 700ppm and that is current status.
Sorry I should have read back more.
I didnt mean to make you repeat that. ;-)
However. Although i have not used coco i still say that plant is not established enough for watering that often. And it is stunting its growth.
Also the ammendments you added make this more of a soil style grow.