DB - let me know if you want to try a 300W PSU with same fixture for another test run - I can send you the PSU and a dimmer. The channels can actually each be driven with more wattage to increase PPFD but I think a dimmer would help a lot controlling light (especially early on). We will be adding this to our line-up in the spring as well as a 480 W with 5 channels for use in 4 X 4 or 5 X 5