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homer

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I just aquired a 250 gal tank with only 6 40W fluorescent bulbs. I want to add Metal Halide's but unsure of which color or brand. I was thinking of using two 250W 6500K Iwasaki's along with 2 fluorescent blue moon's for more color. Would 10K be better?
 

Mike and Donna

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10K is whiter and bluer than 6500. In either case I'd add a couple of Actinics to bring out the colors in your corals. You can also time the Actinics to come on an hour before and go off an hour after your MH, thus crudely simulatig dawn and dusk.

From what I understand, in terms of coral health, growth, etc., the color range doesn't matter too much. In terms of wattage, I think the rule of thumb is 2-3 watts per gallon, though it obviously depends on what you plan to put in your tank. (I wouldn't take my word as gospel on the wattage, btw!)
 

MattM

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First, what are the tank dimensions? That will make it easier to answer.

And, offhand, the Blue Moon probably isn't enough blue to offset the 250W Iwasaki, as they are pretty yellow.
 
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Anonymous

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6500K Iwasaki - usually has the highest par for the given wattage however usually needs VHO blue in order to deyellow them enough.

10,000K German - PAR usually just behind the Iwasaki's for the given wattage (can be higher if double ended) very clean white light with a tinge of yellow or green. Looks best with some PC or VHO blues.

5500K Venture (175,250,400) less par than the German's and Iwasaki's but an excellent bulb for the money. Gives a yellow cast that can be balanced with minimal supplemental blue.

10,000K Coralife, Blueline, ALS, 12K Sunburst, 10K "Euro" - horrible par for the wattage when compared to other bulbs. Often so blue and so low on par they need supplemental white flourecent to provide enough energy corals.

14K Belgian and 20,000K Radium - reasonable on par especially when running 400W - generally accepted that corals color up nicely if provided with a high enough intensity i.e. 400W.

As for which would be best for your tank? The general rule of thumb is 1 MH for every 2 feet of tank length. 175's for tanks with a <18" water column, 250W's for 18-23" and 400W for 23"-28" and 1000W for tanks with water columns over 30". Always best to err on the higher wattage as well.
 

homer

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Should I just go for a dual 400W 10K (instead of 250W) setup and leave off the fluorescent bulbs? If German bulbs are a good 10K, what brand should I look for?
 
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Anonymous

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Have a read here. It will answer some questions. Also this site will give some more information. HTH
 

RedneckCowboy

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If you go with single-ended 250s, the Iwasaki is probably the best bulb. It puts out almost as much light as a single-ended 10K 400.

Double ended 250W 10Ks put out a lot of light, and almost everybody likes the color.

If you go with 400W, 10Ks and 20K (radiums) are nice and put out a decent amount of light. 400W Iwasakis are the king of light output. (Some will claim 250W double-ended are near that level, but I believe those that quote it base it off of a study by Sanjay Joshi who measured the double-ended 250s WITHOUT THE REQUIRED UV shield/glass.)

It matters what you are intending to grow. LPS and softies don't need 400W Iwasakis. SPS and clams like a LOT of light.

If you prefer light with a more bluish tint, go with the 10Ks or 20K radiums, but order the HQI ballast that they perform better on.

If you like your tank to look like it is lit by mid-day sun, Iwasakis are for you. Either 250 or 400s would be fine.

If you want SPS or clams and want 10K or 20K, go for 400W, for these bulbs (at least the single-ended ones) put out a pitiful amount of light in the 250W range.

You can add actinic to most bulb wattage combos to get 'bluer' light. However, I've added four 160W URI VHO actinics on my system when I was running 2-400W Iwasakis, and the actinics barely change the color. VHOs will blue up 250W Iwasakis though.

Remember bulb life and replacement costs. I'd say (my opinion):

12K Sunbursts are wimpy, and worthless at 6 months for $85ish

20K radiums last 9 months @ $110ish

10K ushios last a year @ $110ish

6500 Iwasakis last 18+ months @ $60

An 18 month old 400W Iwasaki looks MUCH more bright than a new 400W Ushio.

I've also seen systems with actinics in which you couldn't tell a 250W Iwasaki from a 400W 10K Ushio.

20K radiums color your corals best.

6.5K Iwasakis are the cheapest, brightest, and longest lasting. It wouldn't suprise me if they have the most growth.

10K AB bulbs are bluer than 10K Ushios (my opinion)

12Ks seem to suffer quality control problems, based on posts.

YMMV, IMO, yada yada yada.
 
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Anonymous

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<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by homer:
<strong>Should I just go for a dual 400W 10K (instead of 250W) setup and leave off the fluorescent bulbs? If German bulbs are a good 10K, what brand should I look for?</strong><hr></blockquote>

You still haven't given us the exact physical dimensions of your tank and the sandbed and the type of corals you plan on keeping. Until you provide that info nobody can give you a recommendation, at least not one worth a damn.
 

homer

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The tank is 6'long 2'wide and 3'high. However the actual water level is only 27" b/c of the substrate.
 

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