Dimmable Ballast -Questions

Get a 600w ballast and be done the bulb wont be affected just change bulb out ever 6 months and you will have nothing to worry about.
600w will get you huge buds compared to yout 250 use the 250 to veg so you can veg and flower at the same time

you can not run a 400 on a dimmed 600, no way. get the 600.

superstoner1 said:

you can not run a 400 on a dimmed 600, no way. get the 600.

Click to expand...

Wrong information stoner.
Care to tell me why?
I have a 600w quantumn dimmable ballast and it has 50 percent setting 300w, 75 percent setting 450w and 100percent 600w
I run a 400w hps bulb on the 300w setting AND the 450w setting nothings happened.
Lumatek sells 400w ballast and they have the super lumens setting whitch runs a 400w hps bulb at 440 watts so with me running 10
more watts that that it has never gave me any problems probly just make the bulb not last as long. But that doesnt mean any thing because i change the bulb out every 6 months.

There are two types of these digital ballasts.

One the one hand you have dimmables:
For sure quantum and hydrofarm phantoms fall under this category. According to the manufacturers, if you have a 600w dimmable, you should be running a 600w bulb all the time. According to Hydrofarm, even if you are running it on 60 or 75%, you are supposed to use a 600w bulb. The ballast will ignite it as full strength and then dim it down.

Now for some contrary information:
According to the manufacturers of bulbs (Hortilux specifically), Running a 600w bulb (or any wattage bulb) at lower than the listed wattage will "adversely affect the spectral output". Now, this is merely rhetoric, and I've yet to see any bulb manufacturer back up these claims with any quantifiable evidence. Then again, they are the manufacturer and you'd assume they know their bulbs. If you follow EYE Hortilux on facebook, their rep is claiming that he's going to have their lab do a spectral analysis on a bulb running at full capacity vs a bulb running on a dimmer. But so far, no one seems to be able to PROVE that it's necessarily a bad thing.

The other type of ballast is the switchable. dialawatt. whatever they're marketed as.
I believe that CAPs digital ballast and maybe lumatek falls under this category. With these ballasts, you're supposed to switch out the bulb based on the wattage you select on the ballast. ie run a 600w bulb in the 600 mode and use a 400w bulb in 400 mode.

This isnt to say that you cant run a 400w bulb in a 600w dimmable hydrofarm ballast, or that you cant put a 600w bulb in a CAP ballast and set it to 400. I'm sure in either case that you will get light, but this is not in accordance with manufacturers recommendations.


I think the conclusion to draw here is that you should buy a ballast that suits your needs. Dont buy a 600w dimmable and make a habit of running on 60%. The dimmable feature is best suited to be used when introducing new clones to a grow, that perhaps dont need all 600w of power. It's also nice to be able to dial the ballast back on an abnormally hot day. But for the most part, you should try to run your bulbs at full capacity.

i must apologize. sorry. i was going on my exp and what i have read. i have the phantoms and was probably going off that. what i can say is that i agree with getting what fits your needs. dimmable was not a needed option for me and i have not ever tried mine. 100%.

Thanks for the info. I know I should run it at full capacity and I hope I wont even have to dim it.
But since I havent set it up yet, I have no idea what the temps will be.

I was already having problems with my 250w air cooled hood set up, temps would reach 29C (like 86F) or even more. only in rare occasions tho. Usually around 80F-82F.
A big factor must be that I cant get fresh air directly into my closet. The closet just gets passive intake from the air in the room. Also the exhaust isnt directly hooked to outside. The least i can do is leave window cracked open.

Just in case it turns out that 600w will be too much for the bigger tent, i will be forced to tune it down.

So I was thinking, if it wont hurt the bulb nor the ballast to run it at 400 if i have to... then the 600w ballast would be the smarter choice.
The time will come, where 600w will easily work when i get a better spot to grow. It saves me money =)