Plants not doing well part 1 of 2

[Baffled and confused]

Plants are grown in rockwool, fill and drain system. PPM is around 800. I'm using Technaflora plant products. lights are on 24 hrs. during veg. As you can see by the pic's, it's not a big problem yet, (I don't think!!!) What I have noticed is that my root system is not really growing. Stunted growth, I beleave I have a deficiency with my nutes. I need a course of attack to fix my problems. Any help would be greatly appreciated

[postmandave]

i dont know much about hydro but root growth stunt is down to a phosphate deficiency.hope this helps . postie