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What is a Conversion Bulb?

Smokin Moose

Fallen Cannabis Warrior
A Conversion bulb offers you the opportunity to switch the bulb in your Halide or Sodium fixture without changing ballasts.

Many cannabis gardeners prefer Halide light for vegetative growth and a Sodium light during blooming but a separate fixture is normally required. A Conversion bulb is a convenient option when you only have room for a single fixture but want the advantage of both Sodium and Halide lighting.

Please Note:
High intensity discharge conversion bulbs are system specific. Sodium conversion bulbs are designed to be used in metal halide or mercury vapour fixtures only. Halide conversion bulbs are designed to be used in high pressure sodium fixtures only.


New Member
Conversion Bulbs has a added benifit of having both MH & HPS light specturm, depending on the manufactors you can get more red or more towards the blue specturm, example the "Cool Deluxe" by SunMaster one of my favorites (by experience) for Veg cycle, HPS ballast, a bulb thats puts out 6500k at 50,000lums.(600 watt conversion HPS) and the bulb itself runs fairly cool.
The 600Watt is said to be the most cost effective (per lum) This is why, lets say 1000 watt HPS, the closest you can get your plants for 1000 watt is anywhere around 2 and a half to 3 feet distance to the bulb, you lost almost half or more of the lum that the bulb puts out.(1000 Watt has 115 lum but at 2 ft I get only 28.750 lums, at 3ft I get 12,777 Lums) 600 Watt although puts out less lum, but you can place the light much closer to your plants there by able to give greater lums to your plants ( I have placed my plants a close to 4 inches from the bulb without any damage to the plants using "cool deluxe bulb") the plants are recieving full lums that the bulb is putting out. Iam using 600watt conversion HPS that put out 92,000lums,0 to 1ft you are getting around 92,000 lums ( most plants can be placed within 6 to 8 inches safely from the bulb) at 2 ft it 23,000 lums, 3ft 10,000lums
The 400 Watt HPS puts out 50,000lums at 0 to 1ft, 2ft at 12,500lums, 3ft at 5,555lums, the 400 watt puts out only 30% usuable light and 70% into heat.
You can use one 600watt Hps Conv with cool deluxe( makes lots of branches have to thin) or similar for veg, then striaght HPS bulb or HPS "enhance" for flowering your plants, or as I do it in the green house for flowering, use 2 600, one has Reg HPS and the second runs a enhance HPS (bit of blue spec), both bulbs in same hood, thats 184,000 lums, that cost less to run or just as much from 1000watt HPS, but able to put closer to the bulb and have better control over light tweacking (specturum). What ever your growing this combinations is an eye opener, more fruit more veg and bigger.
Best advice I can give you is talk to your local distubuter, stores, and people like me that have R&D with this type of lighting then make your own decisons based on your needs. There's has been much new advancement made with "Enchance Bulbs"



Well-Known Member
Conversion bulbs are a waste of money IMO. I too fell for the "MH for grow and HPS for flower" hype and spent the big bucks conversion bulbs cost until a very well known grower told me to stop wasting my money. I won't say his name as he writes for another site (no his user name is not a well known animal we hunt here in Montana and Idaho) but I was smoking a fatty with him talking growing and told him i needed a new conversion bulb and he asked me why. I told him why and he almost sucked the roach down his throat from laughing at me. His advice was right. I saw no noticeable difference from using a MH or a HPS all the way through a grow than I did when I was switching out bulbs. I stopped throwing away money and the only thing I switch out now is the time on the timer. I use a 1k HPS all the way through and have extremely great results.
Don't believe me? Do your own side by side trials and you will see exactly the same thing.

Just trying to save someone a few bucks in these trying times.
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Doctor Dread

Nug of the Month: 3rd Place Winner
^ good lookin Racefan. I was lookin into getting a conversion bulb for my brother. I will just tell him what you have just said and save him some money.


New Member
Go with an electronic ballast, no need for expensive conversion bulbs....bulbs for these electronic ballasts cost $110 .....Electronic ballasts burn brighter than magnetic ballasts, approximately 25% brighter. They are well worth the investment...They even weigh alot less :)


New Member
I was smoking a fatty with increasing talk and I told him I need to convert to a new bulb and asked me why. I asked him why and he almost sucked the roach down his throat from laughing in my face. Advice was right.

Bill C

New Member
So what will happen if I use a MH bulb with a HPS ballast, or a HPS bulb with a MH ballast? Will the bulb explode? Will the ballast explode? Will it just not light?

I have a switchable ballast with a bulb of each variety, but don't want to risk damage just to satisfy my curiosity. Anyone ever try this and what was the result?


Active Member
better off getting separate bulbs, the lumen output of conversion bulbs is around half of their fullblooded counterparts.


New Member
I do it in the green house to flowering, and use 2 600, and one reg HPS and the second runs the promotion of HPS both in lamps Hood himself, to be 184 000 University of Lahore, that is less expensive to run or as a lot of hps 1000watt, But able to put closer to the bulb and better control of light tweacking (specturum). What ever your growing these groups is opene eye.


New Member
I have a switchable ballast too. I've had no problems. switched light from MH to HPS, set toggle on ballast to HPS, that was it
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