Dimmable Ballasts

PJ Diaz

Well-Known Member
OK, I just ran some numbers for you. Prolly not exactly what you're looking for because I'm already running a mismatched lamp (250w) in my 400w dimmable ballast. Also, my 600 ballast isn't dimmable. I was gonna swap through a bunch of different bulbs and take photos and do an extensive test for you, but then I got lazy and remembered I have to trim a couple small plants tonight too, so anyway..

The tests were done using the following lamp/ballast combo -- the 400w is a dimmable revolt ballast with 50%, 75%, and 100% settings -- the 600w is a galaxy non-dim:

Reflector A:
400w ballast @ 75% setting w/250w HPS lamp (this is how I normally run my 32"x32" tent) = 6500 foot candles @ canopy level
400w ballast @ 50% setting w/250w HPS lamp = 5100 foot candles @ canopy level
400w ballast @ 100% setting w/250w HPS lamp (no, I'm not afraid to over-watt) = 8000 foot candles @ canopy level

Reflector B:
600w ballast w/600w HPS lamp = 9500 foot candles @ canopy level
400w ballast @ 100% w/600w HPS lamp = 6200 foot candles @ canopy level
400w ballast @ 75% w/600w HPS lamp = 4400 foot candles @ canopy level

Hope this helps.
So You're getting more foot candles at canopy level running a 250hps on the 400bally than you do off of the 600 watt bulb on reflector B? Thats wild. Kind of confuses me too...:?::?: +rep for the test thats very interesting
Keep in mind, the two reflectors are different types and what I'm calling the canopy level is just where I measured at for each reflector and those distances for each separate reflector are different.

At some point I'd like to do a more controlled test all with the same reflector.
 

dgaf757

Active Member
yeaaaaah. theres a reason why they make 400 watt ballasts with 400 watt bulbs.

better lumens, bigger plants this round...next round your house is up in flames.
im good.

i run my 1000 watt thunder dim able ballast at 50%-500 watts.
although i have different settings
50%-500w
75%-750
100%-1000
SL 115%-1150
...but my question is am i going to hurt anything if for the final 3-4 weeks flowering i turn it up to 115%...will it give me significantly more lumens thus creating more bud?
 

vilify

Well-Known Member
It's not the ballast buzzing I'm talking about, it's the lamp. Something in there seems to be oscillating at an abnormal frequency. It only happens when I underwatt, but not when I over watt. I've actually been wanting to take some light readings at different dim levels, so maybe I'll do that soon..
only time i hear it is when i run a non E-bulb on an e-ballast.
doesnt really answer the question, but maybe that info will help you come to some kind of conclusion.
 

BrewsNBuds

Active Member
my question is am i going to hurt anything if for the final 3-4 weeks flowering i turn it up to 115%...will it give me significantly more lumens thus creating more bud?
I want to know the answer to this too. :lol: I just built my set up in the last month with a new ballast that's dimmable, and I only turned it down today to solve a temperature problem (I just launched my flowering room last weekend, still tweaking it). I also still have fans on order and I will add another intake to increase air flow and get the temp down. I want to flower at 100% otherwise its pointless to use a 1000W light. Right?
 

Sencha

Active Member
My environmental controller has a sensor with a built-in light meter. I have Phantom 1000w dimmable ballasts. From what I've noticed using HPS, the 75% setting is just about exactly 75% of the 100% setting. However, the 60% setting is only about 40% of the 100% setting. Also with MH/HPS bulbs, I do lose a noticeable amount of blue spectrum at 60%, but not that much at 75%. So basically, I avoid the 60% setting and just use 75% and 100%.
Phantom ballasts rock!! I have a 600 and I'm waiting on my 1k. Can't wait.
 

daalma

Active Member
Ive used the dimmable 1000 watt lumateks for a couple years and dimming doesnt seem to mess with the life of the bulbs. Ive done whole rounds at 750 in the summer,and i usually dim down to 750 for the last week or two of flowering sometimes. The guy at the hydro shop (yes I know probably full of shit) told me the thing that can run them down faster is when you run them at superlumens/1100 watt mode for long periods of time.
i can tell you for sure superlumens will cut your bulb life by at least 30 percent. it is good to get a bit more out of an old bulb . i am also finding that some of the cheaper bulbs are as good as anything. peace out
 

cxper

Member
I am planning to run a 600 w ipower ballast dimmed 50%. It should draw around half the usual amperage no? I have a very limited circuit and I want to make sure it's safe as possible.
 

phlopalopagus

Well-Known Member
I can say Ive been running both my cheap ipower digi ballast with horti bulbs at 50% for almost a year now with great results. In my 5x5 tent 2 six's at 1200 was to much and two 400's at 800 was not enough. I chose this configuration and ballast for its 50% over 60% from the get go to get exactly 50 watts psf. Works for me!
 
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