Well it depends on what you are growing but try 250 then use 300 during Veg.i already have two 200watter envirolights dude and started flowering my plants and was thinking of how much bud im gona get i got a 250 mh&hps but alittle hot to put in my grow area!!
In the Uk the largest environlight you can get is 250watt, of which I have both spectrums and grew successfully with them, yielding about .35 g's per watt on the last grow i did with them. They are very cool compared to HPS and as long as you keep them no more than 2 inches away from the tops you will do ok. You really need to use lst aswell so the light can reach the buds equally, if you grow a single stalked plant the lower buds will be very poor.Well it depends on what you are growing but try 250 then use 300 during Veg.