Haven't seen this covered, but I'm sure, deep in the archives, it has. Just can't find it! I use 2 - 1,000w HPS lights in my grow room. I was told they have to be changed at certain points as their 'strength' diminishes? Is this true? It makes sense, but don't want to swap out if I don't have to! Does anyone know how often they need to be changed? Should I switch out one HPS for a MH? Someone said I shouldn't be running two HPS....no clue why not...wonky info....Thanks all!
The life of your bulbs will vary depending on the brand. You don't have to swap them out until they die if you don't want to... some people are just picky. As for whether you use MH or HPS, that should depend on if you are vegging or flowering. Most use MH for veg and HPS for flower. Some people use a combination of both spectrums. I am using 2 x 1000W MH for vegging, and I will be using 2 x 1000W HPS + 1 x 1000W MH for flowering.
I swap out mine out every 3 cycles... and if one go's out during and cycle i have a back up until i can order one. just my opinion.