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View Full Version : Impact of Changing From XM 20K to 10K


mtp
12/18/2007, 09:22 AM
RC Community,

I have a SPS dominated mixed reef system. I have been running 250 watt XM 20K single end bulbs supplemented by two URI Super Actinic 110 watt VHO bulbs for several years. The lighting runs on a HQI ballast. It is time to replace my MH bulbs.

I have been satisfied with the overall appearance and growth rate of my corals. The one area I would like to see improvement in my reds, purples and pinks. My reds, purple and pinks are not as bright and crisp as I would like. I am considering trying the 10K bulbs this cycle. I would not like the yellow hue I read about but thought that perhaps the actinic supplementation would overcome that issue.

Does anyone have an opinion about this? It would seem I may address my objective, get even faster growth rates, and not have the yellow appearance I want to avoid. I like the blue aspects of my historical lighting but like the rest of you I am always looking to tweak appearance and performance.

I would appreciate your thoughts.

Happy holidays, Mike

OranguTang
12/18/2007, 09:26 AM
I believe you may need to acclimate the corals because the 10k will be delivering more PAR into the tank. You will be good with the VHO for supplimental.

SuperAWE
12/18/2007, 09:32 AM
You will need to raise your lights and gradually move them back down, or use some layers of screening to block the light, removing a layer at a time over a month or so.

mtp
12/18/2007, 09:51 AM
I looked at Sanjay’s plot of the 20K versus 15K and did not seem much difference. So that is why I was asking about the 10K lamps. On acclimating the corals to the hotter lamps could I do that by reducing the photoperiods? I currently run the 20K from 11am to 10:15 PM. Could I cut back the MH photoperiod to 5 hours at first and add 30 minutes a week? Obviously the safety of the corals comes first. I can’t raise the fixture. I could rig up some sort of layered screening material but would prefer to avoid the hassle.

OranguTang
12/18/2007, 09:53 AM
I think anything that blocks the light should work. Glass panes, light diffusers etc.

There is no reason to reduce the photo period if you are blocking enough light.

mtp
12/18/2007, 10:10 AM
Is it the consensus of the group that my objectives for increasing brightness of my reds, pink and purples could be accomplished without the yellow hue with this change? Clearly I have to acclimate the corals in some fashion over a 30 day period to the hotter lamps.

Paulairduck
12/18/2007, 11:06 AM
if you can't raise or lower the light's, deffinitely start with a six hour photo period and increase it throughout the month( I think six is a minimum for SPS tanks) Go get some screen from home depot and use this to filter some light for the first two weeks. I would try to be @ a 8 or 9 hour photo period when you get to the the two week mark, after that remove the screens and continue to increase to your normal photoperiod.

The par is almost double on a XM 10k from a XM 20 k, I just went through this change and it worked great

VaderWS6
12/18/2007, 12:32 PM
I always start out with a 3 hour photoperiod on new bulbs.

day 1-3 3 hours

day 4-8 5 hours

day 9-12 8 hours

day 13 10 hours


You'll love the growth rate you get from the XM 10k. I run mine on a HQI ballast, and its ultra white, no yellow at all. They stay nice and white for about 5-6 months on the PFO HQI ballast, and then begin to yellow a little. Looks very natural though. I also supplement with 440 watts of VHO actinic.

JPMagyar
01/08/2008, 03:40 PM
I'm actually in the process of doing the exact opposite :) Recently, I have been running 4 x 250 watt XM 10k on PFO-HQI ballasts with 4 URI VHO actinics as supplementation, and now I switched to XM 20k's. When I was using 10k's I did not use any glass between the bulbs and the tank, and I placed my PFO hood only 8 inches off the water with no ill effects to my corals. Even more strange I am now moving my hood significantly higher to see what happens. Based on what I have seen at the Greenwich Aquaria and read about Steve Tyree's opinions on lighting, I am interested in trying less light and focusing on all the other aspects of coral health. So far I'm about 10 days into my experiment, and I haven't noticed any changes, but we'll see. ;) I'll be interested to hear what your thoughts are once you've tried 10k for a while. As for the 10k being "too yellow", I agree wholeheartedly that you will find the 10k XM's on an HQI ballast are "white" in appearance, and with the VHO actinic supplementation the color will be superb. I've included some photos of a few of my corals for future reference. Should be interesting! Have you considered adding a URI VHO Actinic White bulb to try "popping" the red's? I'm actually contemplating that myself. Be sure to keep us posted.

Joe

http://www.bluefrags.com/images/gallery/pictures/20ktest1.jpg
http://www.bluefrags.com/images/gallery/pictures/20ktest2.jpg
http://www.bluefrags.com/images/gallery/pictures/20ktest3.jpg
http://www.bluefrags.com/images/gallery/pictures/20ktest4.jpg