Qwick debate about lighting theories.

[caferacermike]

Ok so I currently have a Oddysea 48" fixture containing 2x 175MH 20K (yeah right who makes a 175 dual end? so should I say 150w?) with 2x 96w PC 12k.

This fixture is atop my 75g. In theory it puts out 542W. Lets say 492w to be safe. I just got tons of beautfiul SPS from 2 very pushy and very proud SPS growers, ScubaStevo and Fishy Pets (Thank you both your tanks rock and you both have great attitudes about the hobby and new enthusiasts), I'm hoping all goes well. The pieces are currently all about 4" from the water line and the light is 10" above the water line as I fear I do not have enough light.

My dilemma: I am thinking I could easily take apart the fixture and slide in a 250W DE bulb between the 2 175s. This would tak me all of 10 minutes to complete. Adding a 250DE will that actually increase my light and penetration? I know it will up my wattage but is it useable wattage? Would I be better off scrapping everything for 2 or 3 250w bulbs? Will 250w bulbs really do the trick so that I can put my SPS lower in the tank?

See I realize I can keep adding light but am I adding productive light, that's my problem. I was even thinking of adding another 48" fixture of the same style and set up from Coralife as a friend has a new one not being used. But would 4 150w de bulbs really make a difference like a 250w or 400w bulb would?

Now I am begining to learn about PAR values and such. It's all so confusing. I upped my lighting from 240w PC when I first set it up to my current fixture thinking I was buying a great light set up and now 6 months later I am learning my lighting may be inadequate.

Please, I don't want to let Clint or Steve down.

[alton]

Try starting with a lower kelvin lamp like maybe a 14K to increase your light levels. If you want to change to 250w you are going to have to find a way to get rid of the increased heat that the new 250w lamps are going to add. On your PC's I would go with an actinic and a 10K. And remember PC's work but lose lighting levels every 8 to 10 months. MH does the same. Buy a cheap light meter and check it every three months. If you like the blue look, try 150w DE 12k Reefflux lamps. I am sure you will get plenty of ideas today as people chime in.

[GaryP]

IMO 20K are never suitable for a tank. You just give up way to much PAR for what you spend in electricity. They may be "pretty" but there are better ways to get good color without sacrificing PAR.

I would go to a 10-12K MH and ditch the 12K PCs for some good true actinic PC bulbs. It seems your lighting set up is backwards of what most successful reefers are using.

[caferacermike]

Guys the fixture just came with those bulbs and yes I do not want them. It's not the spectrum that I'm asking about, it's the wattage. Heat is not even a consideration in my setup as I have a 1/2 hp chiller for a 75g. I'm wondering if having numerous low wattage lamps is the same as having one giant wattage lamp?

My question is: Would adding another 250w mh be appropriate or would I be better off with a 400w single?

That's my only question at this time.

[alton]

I wasn't talking about the heat to your tank, but the heat to the light. You are going to be doubling the heat to the fixture. The PC ballast are probably mounted internally and they would definitely start to cook. I have done something similar to what you want to do but I added an additional fan to dissipate the heat. I changed my Orbit light from 4-65w pc's to 2 - 175 SE MH Reefflux and it did a great job on my 75g. One 400 would not give you even light, if you go up in watts, it would be better to go with 2-250's for a better distribution. Keep us informed I am sure a lot of people on this site are thinking the same thing you are in going up in wattage.

[caferacermike]

Will do. I do have an external ballast for the PC lights. The only transformer in the fixture is for the fans. I have already upped the fans as the first ones were to slow. I was going to drill about a thousand holes over the new light just as what was done over the existing lamps. Had also thought about mounting fan directly over the holes forcing air into the fixture as the other fans draw air out. I'm starting to lean more towards just getting a new fixture with 2x 250w bulbs from Sunlight Supply.

[GaryP]

Multiple bulbs are always better in my opinion for two reason. 1. Better light distribution, and 2. multiple lights allow you to use different spectrum for better color balance.

[caferacermike]

Really I just want to know what will penetrate to the bottom of my 75g. I had been hoping someone would say that yes adding a nice 250DE in between the 150s would actually help. So far no one has actually said that.

So I've been looking at the Sunlight supply fixture that includes 2x 250w 10k and 2x 54w T5 actinics.