The 1000w hps mh combo lamps are 60% hps and 40%mh.....according to their data that combo percentage will produce the best results for people seeking "blue" light.
Didn't know we were talking about the lamps with both bulbs built in.
And the university of Michigan explains different types of plants need different amounts of blue/red light for best production results.
Leafy greens would require more percentage of Blue to make the best leaves. Cannabis requires more red when flowering to help yield and flowering response.
So there is no one perfect horticulture bulb just because Hortilux made a product.
And the 400 and 600 need to be at different heights to be effective. I think that is why the double bulbs are not very popular.
Do some research. Most growers that mix bulbs go 2 to one with single ended. Or 1 1000 de to 1 315.
Going with more mh or cmh hurt my yield 30%. And the quality was not better.
Also one of those sides of the dual bulb may burn out prematurely. Expensive replacement for half a bulb.
This is what I have found from extensive research and testing.