Yap! Hving more MH will result in higher power comsumption which means higher electrical bills!!!
As for the chiller, I think it's a yes and no cos with and without my MH, there isn't much diff in the kick-in time which I think it's partially due to the height of my MH ( ard 1 ft abt water surface)!
Feels like a nvr ending story as it will be a big loss if I upgrade my lighting fixture now taking into acc the initial $ I spend on it!!!