LED Grow Light

Good question. At that height of your box, there is not a lot of vertical space, with respect to the recommended distance to canopy. If you successfully grew healthy plants with the HPS light, then following the same pattern with LED should be equivalent. - - - > Lots of LST, topping to keep low. I too have a low ceiling on my box, and I did buy a 300w LED array, but it has dimmer function, to account for that extra power. I have not used it yet, and history has shown me, that using my previous 240W LED (fan cooled), that I could get to within 8" to top of plant. That was the limit before I saw any discoloration or crispy leaves. But that might depend on strain, as my Blueberry ate up the intense light. Hope this helps.