I'm not so worried about your light. Tell us about your table.

If it's a flood and drain with large rockwool cubes it should not be running all the time. Sounds to me like your rockwool is staying too wet. A drip system is the only system that can run 24/7 but eveb then you can have problems. Should be running for 15 minute ever 2, 4 or 6 hours or however long it takes to fill the tables.

Getting the heat down will help too.
LOC NAR on probation Reviewed by LOC NAR on probation on . hydro, pump on constant?? first grow, i have some curling in leaves and the bottom leaves are starting to go brown from starting out as brown spots, iv read this is due to heat stress as ther was very low humidity, im using 2 600w sodium, just switched to 12/12, im hopeing this will give them more time to rehidrate, im also thinkin off swaping a 600 for a 400 to take the heat down a bit, i have good intake/exhaust both are 5 inch, big blow fan, using a ikon 18 table with rockwool, temp has been a little high at 30 - Rating: 5