HPS/ballast issue.

Having an issue with my HPS bulb. MH bulb works fine. Went to 12/12 and changed to the HPS bulb. Was working ok, then one morning when I went out to check on the grow it hadn't come on. Juice was getting to it since when I replaced it with the MH it went on immediately. Contacted the people I bought it from and they sent out a replacement bulb.

Got the new HPS bulb, replaced it the next am and it lit up fine. Went out the next am, same thing not on and when replaced with MH works, fine.

Just to make sure it isn't bulb issues I bought another HPS from a place local. Yesterday before the timer went on I tried the 2nd bulb again and it worked. Went out this am and same thing, not on. Tried the local bulb, again not on. Tried the MH, on right away.

So I pretty much feel it is a ballast issue. I have a 400 watt digital conversion ballast. As soon as my grow is over I'm going to take it to the local shop to be tested.

In the meantime just thought I would run this by everyone in case there is any suggestions other than checking the ballast.

Thanks

Okay, it's a dual ballast that can fire EITHER type of bulb? This is like asking 'is it plugged in', but are you certain you toggled over to the HPS mode before switching bulbs? I've never used one of these but there should be a switch on it somewhere.

Man, I wish it was just a switch. It doesn't have one. Suppose to be controlled by a microswitch, which I'm beginning to think is the issue.

Just curious, how much of a difference of flower time would you say there is between the MH & HPS bulbs?

I have a Lumatek digital ballast that runs both MH and HPS. There was a note included in the box that stated it might not be able to fire certain bulbs because of power draw needed to spark the bulb. The bulb you're using may be border line and only fires sometimes....?

Haven't had an issue with a solarmax MH and hortilux HPS. What bulb are you using?

The bulb that came with it was in a generic box and has no name on it. The one I got local is a GE lucolux.

That power draw thing is interesting. But I would hope they would have sent the right bulbs with the set up.