I have a Roc it Fuel in a 2x4 by iteslf now. It is filking the space well. Good luck, I have 2 different phenos. Just starting to preflower. The 1 pheno has AMAZON jungle fan leaves. Has some massive fan leaves and grew out of the giant ones eventually. The other Roc it Fuel was tsller and more narrow, but they were grown under seperate spectrums. 6500k makes bushier and more bendy plants. 3500k makes denser stalks and less bushing out. The Red spectrum in Veg creates different structured plant than 6500k. I typically use a Mixed spectrum. But in a 2x4 if you run 1 6500k and 1 3500k, it becomes 1 plant per light and not a mixed spectrum. You need 3 t create mixed spextrum in a 2x4, but need Gorilla tent for height when using 3 Cobs in a 2x4. My Light Bar light is super bright. I hope not too bright, I have it on about 80% and 18 inches away. I was told 12-18 inches is good with air movement. But when you switch lights mid grow, plants can react. Lets hope it is all positive reactions. Only been a few days with new light. I might do 20/4 to give the plant a little rest. True test will be next run. From start to finish. I will.know how the plants grow and how far to keep light away for my needs. Peace, slow