Hello Izzie1701,
First, do you have any pictures? A picture is worth a thousand words... 3-4 pictures are worth 3,000-4,000 words...
1. How big are the plants?
2. What is the water temp (day and night)?
3. What is the air temp (day and night)?
4. What
nutrients are you using?
5. How are you mixing the nutrients?
6. Are you growing them inside with
lights, or outside?
7. What are you using for your water source?
8. What is the pH?
P.S.
If the rockwool is saturated the roots could be suffocating, and/or the plants could be developing stem rot.