Plant stopped growing went yellow.

So I just pulled out the worst plant in my room, I pulled up the roots and had enough to fill half a shopping bag, basically two handfulls. this plant has been in for over 3 months and in a 50 L pot. I was using Roots Accelurator aswell so the root system should have been enormous.!

What causes a plant to do this, are my plants diseased?? I am assuming both of my remaining plants are the same, should I rip them out and start over with the clones I took from the same plants or will they be just as bad?

Ive tried everything I know and some things I didnt know to fix this and nothing has worked, Ive spent loads on nutes, and light bills for nothing so far!

Please help.

What nute levels/strengths were you using? Sounds like a nute lock out. Pics would be helpful to see for sure. Let me know!

Peace

was using CANNA nutes as per my other post you can see pics of how big the plants were, I started off at 800 ppm and gradually made it up to 1400 ppm over 5 weeks. which should be enough but after 4 weeks the plant just went yellow and stopped growing.

Have you flushed them?

Flushed them with copious amounts of fresh water, up to 150 litres each or 3x times the volume of the pot for each plant, and let them run on fresh water for 24 hours. I hahve done this several times.

my new clones are looking very good, they have gone a nice green and are showing no signs of the mothers ailments.