Burning and yellowing leaves

think you were right about light-related. without efficacy, hard to know from watts to make a suggestion. if the lights have an accurate umol/s rating on spec sheet, you can divide that by your area in m^2 and then use that value along with hours of operation to reference a Daily Light Integral table. DLI is the key measurement for light. 35-40 is a good starting point for a lights output if focused well on a specific area in a tent. This calculated value is probably higher than actual, but just an offset. it'll be consistent. In either case, you still have to adjust based on what the plant does. the calculation just puts you wthin a +/- 5% in most cases. if calculating from total light power, shoot for 40 DLI. This is safely high enough that you won't short yourself. If you have a 500 usd quantum meter taking measurements throughout at the canopy, lol., you probablay want to shoot for 35 to start. hanging distance should be about best coverage from end to end possible without sacrificing too much in the middle. Average umol/s of PAR at of measurements throughout canopy. Not saying you should do this, but explaiing general concept of understanding light applied to a plant. Use dimmer to adjust based on plant behaviour from there. If dimmer not possible, then you have to adjust height, but hopefully up and not down as that sacrifices the corners and edges, and up improves it slightly, but costs a bit more per gram. no matter what the plant dictates it all.