Help me diagnose what is wrong with my light (600 watt HPS)

I got a 600watt hydrofarms light on Craigslist (used obviously). The light has been fine for the past month, but today when I looked in the tent it was much less bright than it normally is. It still has the same colors, just the intensity has gone down. I had an issue last night where it ended up getting unplugged and replugged in several times in a short period of time; could this have caused an issue?

From googling, it sounds like maybe the capacitor inside needs to be replaced? At first I thought it was the bulb, but from what I've read the bulb changes the light color as it dies, and it also happens slowly; this was like an overnight 60% drop in light output, with the same color

could be the bulb dying

Will the bulb just go down in intensity, without changing colors or doing any flickering? It is basically staying at the same intensity it has when it first starts up, instead of increasing in intensity for 15 minutes like it used to

Simple thing to just swap bulbs and see if the bulb is the problem. You should ALWAYS have a backup bulb, even a used one.

Yea I just bought I new bulb, it'll get here Saturday

I like having a spare ballast and bulb around and since I have so many lights it does come in handy often. Have a used spare bulb and you can pop it in for a dead bulb while you wait for a new one. I find bulbs and ballasts always like to go out on Saturday after the grow store by me closes and they won't be open until Monday lol. Plus having spares is handy when troubleshooting as you are. Swap a bulb or a ballast and see whats what. Keep those peepers peeled on craigslist and you can get a spare ballast when they are cheap, maybe a better digital one and make this one your spare if it's still good or repaired with a new capacitor.

Everything you said makes a lot of sense and sounds like the right way to do things!

We don't even have a grow store near me so I have to wait for Amazon; however I'm only growing for myself and I've only got one hps AND I'm still on my first grow so it's hard to invest that much up front.

A capacitor only helps it start. Replace the bulb. With a good one. Eye Hortilux from Amazon. Buy it at a store and pay a hell of a lot more.

EmmaEmma said:

Everything you said makes a lot of sense and sounds like the right way to do things!

We don't even have a grow store near me so I have to wait for Amazon; however I'm only growing for myself and I've only got one hps AND I'm still on my first grow so it's hard to invest that much up front.

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Did it come with a Metal Halide bulb? If so pop it in. Be aware you should not touch the bulb. Use a latex glove or paper towel to remove or replace.

New bulb didn't help, I'm considering getting a new ballast. Current ballast is a Hydrofarm magnetic ballast from 2007, hooked up to a hydrofarm rd luminaire hood. If I get a digital ballast, will that work with my hood?

Skip the digital ballast. Just get a replacement magnetic. Digital ballasts can cause all sorts of issues. Its never recommended to turn a light on and off multiple times in a short period. The ballast and bulb should have time too cool off between each time. I've had bulbs decide to blow and a ballast decide to go out over the years. Both times were directly linked to issues where the light came on and off multiple times in a short period(power outage flashes, out just long enough I couldn't get to my light to unplug it, and then turned back on). From my understanding, this puts a lot of stress on all the active lighting components.

Thundercat said:

Skip the digital ballast. Just get a replacement magnetic. Digital ballasts can cause all sorts of issues. Its never recommended to turn a light on and off multiple times in a short period. The ballast and bulb should have time too cool off between each time. I've had bulbs decide to blow and a ballast decide to go out over the years. Both times were directly linked to issues where the light came on and off multiple times in a short period(power outage flashes, out just long enough I couldn't get to my light to unplug it, and then turned back on). From my understanding, this puts a lot of stress on all the active lighting components.

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I have to agree with the magnetic ballast recommendation.

I just got thru replacing capacitors in 3 old magnetics and dd a lot of research about them while working on them.

A sudden drop in light intensity can be caused by a dying capacitor so I'm getting a multimeter that can measure the capacitance to check mine. I use good bulbs like Hortilux mostly so want to get all I can out of them.

With an HPS ballast that won't fire a bulb at all it could be the ignitor. If you have an MH bulb put that in and if it fires OK then the ignitor is shot as I found out after replacing the capacitor in a 400W HPS ballast recently. I got it dead from a buddy and the guy at the electrical store in the city sold me a 21mf cap instead of the 55mf it needs so that cap went out after a year and while it worked I was likely getting much lower light from the bulb too.

Put the new cap in and a 400W HPS bulb wouldn't fire up but the MH one fired fine and looks super bright with the new cap. So now I need a new ignitor for it. Both my 1000W ballasts packed it in too. One is MH only and after putting a new cap in it still didn't work. I think the coil is shot on that one as I'm only getting 125v at the bulb end when it should be around 550v. The MH/HPS ballast works fine now with it's new cap and is running my 940W Hortilux conversion bulb in MH mode just fine. It also fired a 1000W HPS bulb great too but the Hort has a much better output than the Light EnerG 1000W Super HPS going by intensity measured with a cheapo light meter. It reads 1500 at 3ft while the other reads only 1000 and it's hard to beat a Hort for actual light quality. I did my testing on the 1000W MH/HPS with the old capacitor in it not long before it died so should do it again with the new cap and see what the results are.

I'm using that monster in the middle right now. A lot of money for those so will be getting the standard Hort SHPS when I need to replace it. Will be replacing it with a Light EnerG bulb or maybe that Sunmaster which is another conversion bulb but has only just over half the intensity but is way higher in red according to its spectral chart on the box. At day 21 of 12/12 the stretch should be over and they don't need as much light to flower well.



These PlantMax suck imo but were cheap and OK for backups.



This is the 1000W MH/HPS I bought about 2 years ago used from a hydro store in Kelowna, BC for $70. New cap was $50. lol