Hi, I live in England and currently it's pretty cold. I have 4 cob lights over 4 plants and a 4 bulb t5 over my younger plants. The question I have is regarding whether I continue to use an oil radiator to keep the tent warm or use my 600w hps? I expect the oil rad is cheaper to run (no proof) but I guess the electric is put to better use with the hps. What do you think people? Cheers