Hi, if you have a 240w Samsung lm301h in a technically 3 X 3, me personally I think that is plenty!! In general a 240w Samsung "fixture" whether its HLG, Kingbrite, Invisible Sun, Meiji etc will all veg a 3 X 3 and flower a 2.5 X 2.5 but again this will depend on quantum board or "cob" style. Me personally wouldn't put a mars none Samsung led in there with a 301h fixture (just think the intensity and efficiency of the 301h will over power the Mars) So the question is, what's your end goal? Yield ? - has the Samsung fixture got red, IR, UV etc all factors for flowering, if not then maybe think about supplementing the 240w. Is your space "dialled in" humidity, temps, air circulation etc, personally I would try my "best" at maximizing the "potential" of the equipment I have and proceed from there! Again it's difficult to give solid "advice" without a diary for reference on how your using the 240w or at least a brand name to see what your actually working with! Happy Growing 👍