MH Help, Please...

[fsn77]

I could use a little help and some clarification about some of the things I've heard regarding MHs... Several questions...

I have this PFO 175w electronic MH ballast. (http://www.marinedepot.com/ps_ViewItem~category~PFO_175_Watt_Single_Electroni c_Metal_Halide_Ballast_Saltwater_Aquarium_Supplies _Lighting_Accessories_Ballasts_Metal_Halide_175_Wa tt_Electronic~vendor~PFO_Lighting~SearchStr~~actio n~view~idProduct~PF1491~idCategory~FILTACBAMHHSEB~ tab~1.html)
It came with a PFO basic parabolic reflector and a PFO Krystal Star 11,000K bulb. It was a retrofit kit I won at the neighboring club's picnic last year, and I'm just now getting around to using it.

A) I wanted to mount the retrofit kit into a basic rectangular pendant, but the reflector is too big to fit properly (by a few inches), so I'm considering purchasing this socket (http://www.hellolights.com/index.asp?PageAction=VIEWPROD&ProdID=532&strVarSel=&strCompare=) and mounting it straight into the pendant's hefty aluminum housing without a reflector (inside of the housing is freshly painted white). How much will I be hurting myself by not having a reflector? It's going over a 15g tank (roughly 24" L x 12" W x 12" H) to grow out frags, most of which belong to the local club and I'm growing out to frag and propogate further for the club to raffle off or give as door prizes at future meetings.

B) While I don't neccessarily need a new bulb at this time, I could surely use a little help understanding the difference between 175w mogul base bulbs. When I look at item descriptions for some bulbs on HelloLights.com, I see this note:

We highly recommend a Pulse Start (ANSI M137) or ARO 150/175W ARO Electronic ballast for this lamp. An ANSI M57 ballast may not start the lamp or burn it properly.
What is the difference between a M137 and a M57 ballast?
Does the fact that I have an electronic ballast make that note something I need not worry about?

C) I also see in the item description of the 175w 20,000K Hamilton bulbs (http://www.hellolights.com/index.asp?PageAction=VIEWPROD&ProdID=1410) that the bulb has a self-starter -- is that a plus vs. a bulb that doesn't?
And, does that matter with an electronic ballast?
I've seen some comments about Hamilton bulbs not lasting as long as other MH brands -- any known reason for that? Considering the purpose for this MH set-up, I'm not looking to replace the bulb every 6 months, so I'd like to avoid bulbs that have longevity issues.

D) Anyone have a preference for a certain 175w MH mogul base bulb in the 14,000K - 20,000K range? I'm not going to have any actinic supplementation, but would still like good color without sacrificing too much in terms of growth.

[archer772]

I believe that electronic ballasts will fire all of the MH bulbs but not positive, with that size tank I would consider running a 20k XM and I know they can be run on an electronic ballast. The 20k XM will not look extremely blue on smaller tanks and you will still get good par from it at least IMO.

[kcress]

How much will I be hurting myself by not having a reflector?

A) Probably 40% over a proper shiny reflector. The pendant may also run hotter as what is not being reflected is absorbed by the paint pigments and will add to the pendant heat.

From a tank perspective... A tank that small with 175W over it will still be lit up pretty bright.

B) C)
I am not an authority on these but let me pass what I know. Originally all bulbs had igniters in them. This is a bimetal flipper in them. You can always see it in the bulb if it's not frosted. Power is turned on. A small heater heats the bimetallic strip as current rushes thru the flipper. When the bimetal strip gets hot enough it snaps open. This results in an inductive kick that creates a high voltage spike across the tube. This ionizes a path across the tube long enough for the arc to strike and the bulb to start.

To improve efficiency, bulb life, and lumen maintenance electronic ballasts came out. A short step from having an electronic ballast is to provide that high voltage spike electronically in the ballast.

Here's where I get sketchy. I think some bulb makers are ditching the in bulb bimetal igniters. So if you get a bulb that has no internal igniter then your ballast better have the provision.

Now in the internal igniter case the high voltage arc stike is created in the bulb. With external pulse start electronic ballasts the pulse is created in the ballast and hence has to be conducted to the bulb thru the power leads and the socket. I know for a fact that many standard sockets will not handle this. It could just not allow reliable starts or it could cause fire issues. A regular mogul base is maybe 2$. A pulse start 5kV rated socket may cost $8.

D) Not I.. FOWLR for a few more months.

[Amphiprion]

I agree with kcress. Depending upon the reflector, 40% will likely be a conservative estimate. It is almost as much waste as not using reflectors on T5s. You can see dramatic differences with a PPFD meter. For color, have you tried the Reeflux 12K bulbs?

[fsn77]

Thank you for all the info!

This is the reflector that came with the retrofit kit. (http://www.marinedepot.com/ps_ViewItem~action~view~idProduct~PF2631~idCategor y~FILTACRAMH~category~For_Metal_Halide-Reflectors-Accessories-Lighting-Saltwater_Aquarium_Supplies~vendor~.html) Any real harm in trimming off the last section from each side to make it fit into the pendant housing? I'm guessing a trimmed reflector would be better than no reflector.

To be honest, this is my first go at MHs, as I really like T5s. This is one of those situations where I have this light, so I might as well be using it.

Amphiprion -- You're the second person to suggest the Reeflux 12,000K to me, so it seems that I should take a closer look at them.

[Sploke]

I'd agree with that...a slightly trimmed reflector would be a lot better than no reflector at all.

[Amphiprion]

The 12K Reeflux bulbs do a decent job--reasonable intensity and good color without actinics. Just do some searches for photos and you'll see that they are a good, rounded bulb (my only "complaint" is, when run on standard magnetics, the light they emit has an odd overall color--hard to describe). Some reflective material is better than none. I figured you probably have, but I thought I might check to see if you have looked at all the various reflector/socket combos available. At least one is likely to fit your application and give you bang-for-your-buck.

[kcress]

Yeah, I'm a vote for trimming..

[fsn77]

I searched for some photos and think the 12,000K Reeflux looks like a good choice. It's a pretty reasonably priced bulb, too.

I did just a little bit of searching for a more compact reflector, thinking there must be something just a tad smaller in size, but didn't see anything that would fit without some sort of modification. So, I think I'll trim down what I have (especially since my financial investment in it is rather small) and see how it works. Unfortunately, I don't really a scientific way of determining how well it's working, but I do agree that it has to be better than just using the white paint. I guess the proof will be in the pudding -- by how well the frags grow and the quality of their color.

Thanks again!