Actinic or 20k bulb?

[EQCM2B]

I plan on putting in a 250 watt MH in my 44 gallon corner tank. My question is do I still need actinic lighting if a get a bulb that has more blue than white in it or would it be better to get a whiter bulb and still use actinic? I understand that my corals need the blue spectrum but is this the same thing or is it different?

[dakar]

IMO the problem with 20K bulbs (lump in the 14K and most 10Ks) is they completely lack coverage of the red end of the spectrum. They may be pretty to look at, but I personally feel there is a price to be paid for running less than full spectrum lamps.

In the simplest terms, when I look up I see the sun as being yellow/white in color, so my tank lamps are the same, so supplementing them with actinics gives us the dawn/dusk effect and makes up for any defficiency for the shorter wavelengths.

[perpetual98]

Very well put dakar. Also, while the higher spectrum bulbs really make things fluoresce nicely, they aren't very good for coral growth, especially SPS.

Then again, if you don't have any SPS and are mainly softies and fish, you should go with whatever pleases your eye the most. My .02

[EQCM2B]

Thanks alot folks. I suppose I need to squeeze in some more actinic somehow after I get my 250 going. Any reccomendations as to how much actinic I would need to go along with a 250 watt say... 10k bulb? Right now all I have is a 10k 15 watt and an actinic 15 watt bulb. Would two 15 watt actinics be enough or do I need to increase that as well? And yes I do want the option of having SPS.

[dakar]

There is no hard and fast set % for actinic lighting as it's mostly for our eyes, but 1/4-1/3 of the total halide wattage seems to be average for most. So with 500 watts of halides around 150w or so actinic should give you a a pretty good staring point... you can always work up or down from there (if you are DIY'ing them)... if it's a fixture then you may want to go a little higher... 2x250 halides with a pair of VHO or quad PC actinics makes a good balance.