If I were to keep my plants under 24 hr light but only use the HPS light for, say, 18 hrs and use fluros for the other 6hrs, would this be ok? The reason I ask is a, just thinking about cost of running HPS24/7 and b, to allow the area to cool slightly,
It would be ok, but probably pointless. Just keep them under hps 18/6 or even 20/4 and don't bother with the fluoro. good luck