HPS/MH and Ballast question

Hi all. I was taking a look around town and I couldn't find a place that sold 150w HPS so I took a look online and I came across a 150w HPS but I also wanted to see if I can find a 150w MH but I can only find a 175w before hitting 250w and my question is, can I use a 250w Ballast with a 150w MH or a HPS?

The ballast I was looking at suports both HPS and MH.

nope the bulb could fail and blow up u could use a 250 bulb in a 150 ballast but it might not fire

no, an HPS and a MH require different types of ballasts, the main difference being that a pulse start HPS requires an ignitor in addition to a capacitor to operate, whereas a probe start MH lamp simply needs a capacitor.

there are certain types of ballasts that you can use a lower wattage lamp instead of the full rated wattage, but you can never swap lamp types on the same ballast.
there is not a MH lamp smaller than 250w available for sale to the general public.... they make some conversion lamps, some reef aquarium 150w mh lamps, and some other specialty lamps, but generally, there hard to find.

ok then why does it say the Ballast suports both MH and HPS?

Certain ballasts allow the use MH or HPS, but only the correct wattage for the ballast. Mine, for instance, will fire MH or HPS in 400 or 600w. You just need to make sure the settings are right. You can't just throw a 400 into it when is set for 600.

ok well I whent to place the order and they only ship with in the US. any one know of any good hydro places in Canada?

some low wattage HPS ballasts are also capable of running MH, the smaller HPS ignitor has enough ass behind it it can safely send a high voltage pulse to start the MH.
the bigger the MH lamp, the more risky this operation is. if you move up into the 400w class, the ballast will have to have a separate ignition circuit to run the MH lamps, there also known as selectable output ballasts. Your ballast is not selectable output, but like i said, the ignitor has enough 'ummmmmpf' behind it to work. Long term operation of a non selectable output HPS ballast with a MH lamp will shorten the lifetime of the MH lamp. Basically, it causes blackening of the arc tube on the MH lamp, which degrades heat radiation, which in turn causes excessive heat buildup inside the glass encapsulated arc tube, which, over time, causes premature lamp failure. Its something that happens over months, not days, so its hard to notice. that makes it dangerous, because when an HID lamp fails due to excessive heat, more often than not, it explodes. that is why there is a capsule within a capsule in every HID lamp, if that lamp blew with just one layer of glass, the sudden exposure to oxygen of elements burning @ 4 times the surface temperature of the sun, explosions happen.........

If I bought a 250w HPS Ballast and a 250w MH ballast can I buy a kit so that I can convert them into a 150 or 175 ballast?