6700k or 18000k
 

The facts

I know 6700K is more in line for fresh water planted tanks but is there going to be that much of a difference compared to 18000K based on the following


20" water depth
Lps and softies

I have run only the 18000k bulbs from the start but wondered what I will loose buy going to 6700K. Also any benefit in running a combination of the two or stick to one or the other.

you will lose any hint of blue you may have ever liked! That will be super yellow...but bright as hell I imagine. This metal halide?

Oops I guess I didn't give all the facts... It's T-5 Hagen lights which I'm stuck with. Unless I can find other 22" bulbs. The choices are 6700K, 18000K or actinic which seem way too blue.

Well the colour comment still applies...not sure how PAR is affected with those bulbs.

Any t5 HO 24W are ~22", Bayside would have them in a 14000K or close. Pair up a blue (actinic) and daylight (14000K) lamp. You may find you have an algae issue with any 6700K. Would be great for macros though.

Mix the bulbs. One of each.

If you can only have one bulb, I'd go with the 18K.

euphyllia and lps really like the blue spectrum from what I have read...

plus, an 18k bulb is much less likely to promote problematic algae growth.



If it were me, I'd do a mix of them if possible and go from there.

I will have to give them a call, from what i've read 14000K seems to be the bulb of choice vs. the 18000K. I know the benefits of actinic but when I tried one with a 18000K the tank seems too dark.

If it was my tank I'd go with 2x 14000K.