I'm growing a crop that likes it cold, around 14 to 16 deg C. I thought that leds would be the way to go but my ducted cooling system is struggling to keep up. Then I realised that while there is less radiant heat output from these, there is actually more conducted heat (vs hps) which means there's not that much difference with the total amount of heat going into the grow area, to be removed. To run as a sealed room/ tent I'm now thinking that water-cooling the fixtures may be a way to take the load off the ducted air system. I used the grow things with water-cooled HPS bulbs and heat removal was not such an issue, using a combination of venting to out doors and chilled water (fan/ coil unit for some air that was recirculated). I wasn't running CO2 but did use multiple lights with 1000w SE Hortilux for each sq.m (single plant per light btw). So has anyone done water-cooling with LEDs?