Gl you've just gone and grown them babies too big.

I think your plants are rootbound. If you aren't using a zyme product then start asap and consider flushing to help get any excess crud/fert build up, old dead roots etc out.
This is something that all of us with waterfarms have run into sooner or later which is why everyone drills extra holes in all their w/f buckets and there STILL seem to be issues which is why I went to 8 inch net pots instead.

There isn't anything you can do really except use your zyme products and try to keep drainage and 02/water flow open for the roots inside your red buckets. If you don't develop root rot problems they may finish ok.
Weedhound Reviewed by Weedhound on . First Time DWC W/ Water Farm Buckets This is my first Bucket grow ever. I have done tables before and had great results Soil ect... Then I seen the excellent results People were getting out of 4 bubbler plants with LST. So I Just purchased 2 8 pack Water Farm Bucket Systems. After 5 days I can see that I need to buy a stronger pump and more line cause I cut it all down. I'm running tap water 7.8 dropping it down to 5.8 to 6.3 W/ PH Down. I set up the system without washing the Hydrotone and balancing the PH level of it. I did Rating: 5