Radium bulbs underdriven

[Chad_P]

I’m new to MH, bought a giesseman spectra 72” for over my 180g SPS tank. Ordered 250w bulbs. Installed the bulbs and set up in November. Just yesterday one of the bulbs went out. Took it out and realized it’s a 400w bulb, somehow overlooked it labeled on the bulb as the sticker said 250w. Obviously having the 250w in hand there is a noticeable size difference. Now makes sense why I was probably frying some corals.

My question is do I just stick with the 400w? I’m thinking so just to be consistent. Ive got the fixture about 12” above the tank and everything is doing well.

Also, I’m worried the other 2 bulbs will be messed up. By thinking they were 250w I’ve been running them on that through my luxacore adjustable settings. So basically they’ve been under driven for some time.

 

[jda]

It is a good idea for them all to match. Unless you are really covering a large area, there is no need to run 400w bulbs. 250w MH can handle a 30x30 area at 30 inches deep in that fixture. There is no harm in running 400w, just more power - if you have a well-stocked tank full of light loving stuff, then they might really love it. Only you can really decide what to do here... no wrong answers.

When under-driving or over-driving bulbs, the spectrum can really shift. This is not a huge deal in the usable range, but if the spectrum shifts to include too much UVB, then this could be bad since the glass on the bulb was only made to filter out what the bulb produces when run to spec. I would say that a 10-15% difference in spec is not a huge deal, but 400w bulbs being driven by 250w ballasts has bad stories for a long time. Another real problem is that there are few anecdotes and nearly no real info on this since nobody wants to test and experiment.

 

[billwill]

I didn’t realize a 400w bulb would run on 250w ballast. Maybe that’s why it didn’t last long?

 

[Chad_P]

It is a good idea for them all to match. Unless you are really covering a large area, there is no need to run 400w bulbs. 250w MH can handle a 30x30 area at 30 inches deep in that fixture. There is no harm in running 400w, just more power - if you have a well-stocked tank full of light loving stuff, then they might really love it. Only you can really decide what to do here... no wrong answers.

When under-driving or over-driving bulbs, the spectrum can really shift. This is not a huge deal in the usable range, but if the spectrum shifts to include too much UVB, then this could be bad since the glass on the bulb was only made to filter out what the bulb produces when run to spec. I would say that a 10-15% difference in spec is not a huge deal, but 400w bulbs being driven by 250w ballasts has bad stories for a long time. Another real problem is that there are few anecdotes and nearly no real info on this since nobody wants to test and experiment.

Thanks. I’m gonna replace all with a 250w. If I’m thinking about it correctly, under driving a 400w bulb obviously isn’t giving me 400w. It would be limited by the ballast which was set in the 250 HQI setting. So I was probably really only running 250w but maybe with a screwed up spectrum.

 

[Chad_P]

I didn’t realize a 400w bulb would run on 250w ballast. Maybe that’s why it didn’t last long?

That’s what I’m thinking. I was there when it blew, did it right at startup. Saw a flash then a little pop. Filament busted.

 

[hybridazn]

I would pull the bulbs and replace them with proper 250w bulbs. Yea the 250w ballast will fire and light a 400w bulb, but its severely under driven killing the spectrum and not properly lighting your tank. You are basically wasting electricity at this point.

 

[hybridazn]

I didn’t realize a 400w bulb would run on 250w ballast. Maybe that’s why it didn’t last long?

Correct, the bulb died because of being under driven. Over driving and under driving bulbs always affect bulb life.

 

[jda]

The only real data and anecdotes that we have is overdriving bulbs non-HQI on HQI ballasts - this seems to limit life to about 6 months of useful spectrum and output gets a tad whiter and output jumps quite a bit. This appears safe if you change the bulbs on time.

The only under driving event is people who run 250w radium on electronic ballasts (non-HQI). The output gets lower and spectrum is bluer, but the bulbs seem to last. Radium has indicated in the past that the bulbs can handle this.

Remember that if you get 250w Radiums, they need to be on the HQI setting.

 

[Chad_P]

Thanks all really helpful. Gonna replace all bulbs with 250w and run on HQI setting.

 

[A. grandis]

I would get the M80 ballast to run the Radium 250W.
If you want to run electronic ballast you can get the Hamilton 20K 250W.
Those are the best matches for those 20K bulbs with very similar results.
Run them accordingly to what they were designed for and get the very best out of them.

 

[Chad_P]

I would get the M80 ballast to run the Radium 250W.
If you want to run electronic ballast you can get the Hamilton 20K 250W.
Those are the best matches for those 20K bulbs with very similar results.
Run them accordingly to what they were designed for and get the very best out of them.

Maybe, unfortunately I just bought these e ballasts. Is there that much of a difference? I see the Hamilton M80s you mentioned.

 

[hybridazn]

The 250w radium was designed to run on a m80 magnetic ballast. The m80 ballast runs at I believe 300w, which us obviously overdriving but that is what the bulb is designed for. Running it on an electronic ballast is doable as well, but needs to be hqi. That is around 275w.

 

[Chad_P]

The 250w radium was designed to run on a m80 magnetic ballast. The m80 ballast runs at I believe 300w, which us obviously overdriving but that is what the bulb is designed for. Running it on an electronic ballast is doable as well, but needs to be hqi. That is around 275w.

Thanks. My e ballast has HQI and when I run it at that my Apex is telling me it’s just under 300w. I know the Apex may not be 100% spot on but seems like it’s driving at the same Watts as an M80?

 

[hybridazn]

Thanks. My e ballast has HQI and when I run it at that my Apex is telling me it’s just under 300w. I know the Apex may not be 100% spot on but seems like it’s driving at the same Watts as an M80?

Hqi is adequate for running the radiums. It's close enough in wattage that there isn't much to be concerned with

 

[A. grandis]

The spectrum won't be the same because of the difference of wattage.
The difference isn't that much when you compare the M80 magnetic ballast to the HQI or Super Lumens settings on electronic ballast, but isn't still what the bulb was designed for. The electronic can be used though.
I can tell the difference here when I use both to compare. It's visually different.
With the M80 the Radium is still brighter (whiter) at ~330W.
Using the Lumatek electronic, for example, it will draw ~270W on regular "250W" and ~310W on "Super Lumens".
The Radium is called a 250W bulb but is designed to run at ~330W, so it's not really a 250W lamp.
I think the Hamilton 20K 250W will run better with the electronic. I tested the new Hamilton 250W here and it's beautiful. I also have 175W.
They all work. It's a matter of getting the best out of the bulb you want. If you get the right ballast then you will get the right spectrum.
Prepare yourself for growth when using a 250W Radium with the M80!