CMH bulb replacement

Bumping up my grow a little this time around. I currently have Growers choice dual 315W CMH with just their bulbs it came with (3K-R) red enhanced. Have only done 2 grows with these so far. I’ve read where some people use different bulbs for veg & flower. Wondering on thoughts about doing that? I have to buy an extra bulb just incase one blows so If i am going to buy new bulbs i want to get what’s best. I also added a Spiderfarmer SF4000 so i will be running both lights for 10 plants covering 4x8. Thanks for the help.

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CMH for veg and HPS for flower is what some people will do.

ohh i thought it was just a different wavelength. I will have to check if my light can do both. I wouldn’t think so. Just looked all the HPS are screw in so im not buying a 3rd light. I’ll just stick with what i got and buy an extra bulb. Thank you

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Don’t quote me on this as I’ve never used bulbs, but I believe that CMH and HPS are interchangeable in the same fixture. @dbrn32, true?


Doesn’t change work for veg and flower without changing…

I’m pretty sure you can’t. Just because there is 315w HPS bulb.

I’ve listened to a few podcasts that say 4100k CMH bulbs can grow KILLER weed. Super terpy and great for extractions.

I don’t grow under a CMH, but if I did it would be a 4100k Cultilux bulb or a Hortilux CMH bulb.

I don’t think I can post YouTube links on here but look up this episode of Growcast for more information on CMH.

Negative. At least I have never seen ballast compatible with both. Most digital ballasts will run both metal halide and high pressure sodium, but ceramic metal halide requires its own.


Cmh is definitely different. Different wattage bulbs and the ballast puts out different wattage. Mh and hps won’t work on a cmh and vice versa


Is these a good place you guys like to get bulbs at or just a google search? I’ve found recently best price isn’t always the best place to go. So now i try and ask for recommendations on pricey items. Thanks again for the help.

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I’m surprised no one has responded to this! So sorry for the delay.

Go to Cultilux dot com. Contact them via email or by phone to place an order. (A pain in the butt but worth it) Mention you heard them on Growcast and you’ll get 10% off

Yes, ONLY if you have a switchable ballast, I have a few old dogs in storage, that you have to toggle the HPS/MH switch.

Thank you

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