I have a friend the bought the 10k coralvue bulbs and had a bunch of corals beach from the bulbs swicthed. he put a post on reefcenteral and many others had the same problem. he then call the people who made the bulbs and told them about his problem and they said that they were working on a new bulb design. they thought the bulbs where letting too much UV though and needed thicker glass. this happen about a month ago and the post sould still be on RC. so be careful
CoralVue bulbs(Single Ended) does not give out as much as UV compared to other bulbs in the market. Resulte are in ReefCentral
Whenever you change/upgrade to MH, intensity acclimation is the KEY not duration acclimation, some of people switching bulbs by turn of the MH ballast, replace the new bulbs and turn it back on (or sometime some people switch the bulbs after the light was off at night). Coral bleached, die and start flaming ...
The problem with the old design CV bulbs was they did not have the build in igitor, thus it is harder to fire on magnetic ballast.
When you replace new bulbs/upgrading, you acclimating agains the new intensity of the new bulb not so much with the "how many hours a day" and slowly increase it.
Some hobyists acclimation by start it with 4-5 hours and slowly increase it. Your corals still get shock from the intensity different within those 4-5 hours. And some of hobyist switching the bulbs as I stated above.
The different in intensity in a short period of time will shock your coral, when SPS corals shocked, they are stress out, slimmy, bleach, STN, RTN, die anything can happen.
How about a little experiment with MH(I have done this with 5 different SPS frags). Let's move one of the SPS from the BOTTOM of your tank up to the highest point in the tank and/or move one of the frag from the highest point to the bottom of your tank, let them seat there for couple days. Your SPS WILL bleach. Why, because of intensity different shock.
In the past I have used
Ushio, Venture, Hamilton, CoralVue etc. SE and DE bulbs I do not experience any corals bleaching.
It's took me about 2.5 month (yes, about 8 weeks) to complete 100% acclimation to the new light. I used window screens (6 screens), acrylic/glass top. My photo period do not change. After I switch bulb/upgrading, I add the screens and acrylic and glass top on the tank. I remove 1 screen per week, remove acrylic 2 weeks later after the last screen and finally remove the glass 2 weeks later. I have open top tank and 95% SPS dominated.
I have SPS bleached, STN'd, RTN'd and died in my tank. I'm the one should be blame at because of my poor husbandry, irresponsible or just simply slacking off.
I don't tend to offend any one, just an informational post.