Best Kelvin/Spectrum MH for Zoa Growth

wattson · Feb 17, 2018

Curious to hear peoples experiences with using Meatla Halides for zoa growth..
I have a 250 watt MH fixture with a 20k Radium bulb over one tank on the system and everyone is doing great but feel possibly lowering the Kelvin to spark more growth..
Been reading til my eyes go cross wise on the net but would love to hear peoples experiences and preferences..
I like the blue look of the Raium 20k and have blue led suppliment lighting on the sides of tank..

Broadfield · Feb 17, 2018

I have the same exact bulb/wattage combo x 2 and my zoas love it. I also have four T5 bulbs... Super Actinic x 1 , Actinic Blue x 2 and Super Purple x 1.

Pile of Zoas by Toby Broadfield, on Flickr

wattson · Feb 21, 2018

DSC reef · Feb 21, 2018

20k spectrum with our halides has been great. I don't notice any difference when we ran 14k spectrum halides. I prefer the bluer look.

wattson · Feb 21, 2018

do you see any better growth gains with 14k/17k bulbs 250watt over the 20k radiums?
been reading that 14k with blue light supp. is preferred but rather hear first hand experiences

joshporksandwich · Feb 23, 2018

I've tried 20k, 14k and 10k and i haven't seen a major difference.

wattson · Feb 23, 2018

thanks for the reply,,which k do you think has the edge of being the better of the 3 you listed ?

A. grandis · Feb 26, 2018

No doubt that a 6500K will punch more growth than a cooler spectrum IME.
But... any changes will take time for the zoas to adjust first. The results will be noticed after a while.
Their colors will change also, and the appearance of the whole system will be yellowish, as we know.
Some times the extra growth happens faster to some species than others, but you will need to be careful during the changing so you don't shock them.
The Radiums already provide a nice growth rate and will give you nice coloration!
If you really want to try I would suggest to get a 17.5K or a 14K bulb first and then acclimate the system under that, before going to the 65K. You will need to have the actinics with the 65K, so it doesn't look terribly yellow.

Is it worthy?
I would say not at all, specially if you like the 20K look! Your Radiums are one of the very best of all lighting options for the majority of the reefs kept at home.
Grandis.