I'm looking at putting together a new lighting setup and had a few questions.
First of all I'm ordering a 400W HPS, a 400W MH, and a 250W HPS.

Do I need to get two ballasts since I'm running HPS and MH? Or can a digital ballast handle both?

How many lights will you be running at one time ?

It works like this;

400W digital ballast will work with 400 MH or 400 HPS bulb. One ballast per bulb. Make sense ?

Can I plug a 400W light into a 600W ballast?

Sure you can, but based on what I have read I wouldn't advise it. Sounds to me like you could blow the bulb or even worse start a fire.

this is a picture of the lumatek dual (hps/mh) digital ballast... it is two ballasts in one, priced accordingly. you can't plug a higher or a lower wattage bulb than any given ballast is intended for, however, you can run a mh out of one plug and an hps out of the other on this pictured ballast, which would make your grow fucking kick major ass...

of course, that promises quite a bit larger electric bill i care to deal with.

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cheers ~LoveIt
check out my current somango/ww grow! (and don't forget my 1st bagseed grow journal- cured and in')