Thought about that yes but its currently no option. I already have a complete 400MH and a 600HPS. Since we have extremely high temps in holland at the moment, I hoped I could just get a 400HPS bulb and use that temporarily untill temps drop enough to use the 600.

For next grow I'll rebuild my setup anyway and will surely consider dual ballast.
HeartCore Reviewed by HeartCore on . Ballast question Hi all I got a 400W MH lamp with a ballast. Also have a 600W HPS for flowering, also with a ballast. Problem is, I'm vegging with the 400W but the weather is just too hot. I can manage temps with difficulty. If the weather doesnt change soon, I will have major problems with flowering once I switch to 600HPS. What I want to do is to get a 400W HPS bulb for flowering, I'll use the 600W exclusively in winter. Question is, can a 400W HPS bulb be safely connected to the ballast of a 400W Rating: 5