Changed VHO Bulbs-question on corals

[basssnake]

I changed out my VHO bulbs about 2 to 3 weeks ago. The old bulbs were 10K(3 of them) and one blue actinic and about 5 years old. I finally decided i better change them since i was having some issues in the tank with a little hair algae and slime bacteria(cyno). I replaced with the same brand bulbs but went with 12k on the main three and the same type of blue actinic. So, the light spectrum is for sure a lot different(also i am sure the old bulbs lost a lot of their color).

Now, my zoanthids and mushrooms are not opening as good as they were. In fact, some of my fast spreading zoanthids were before having clumps of them with lots of "bumps" on them(which are spots where new polyps would grow off of). They would be really swelled up and the stems would be long. Now they are short and don't seem to be as full and i don't see any of the big clumps that were just swelling with potential growth. Could it be the light(with the old bulbs) was not as bright therefore they were trying to get closer with the longer stems and made them look fuller? I can tell that the new bulbs look a lot brighter.

I am just wondering what is going on. Does it take awhile for the corals to adjust to the new bulbs(especially when going from 5 yr old ones to new)? If So, how long normally? Approximately how long til the corals will open like they used to? They open now just fine(besides mushrooms don't get as big as they did with the old bulbs), But i want the mushrooms and zoanthids to be fuller like they were.

Thanks for any help......

[Mattik]

You might want to shorten the light cycle a bit to see if it helps with the "shock" from such brighter lights. If the old bulbs were 5 yrs old, then switching them out could have the potential to shock the corals a bit.

Since they are opened up now, it may just take some time for them to completely settle back in, but the shorter cycle may help as well.

[basssnake]

So, after two or three weeks of them being on the same amount of time, i should shorten the cycle now? If so, how much should i shorten the time to?

[Mattik]

Whenever I adjust my light cycle, I do it in 30 min increments, where each week I change by 30 mins until I get to where I want to be.

Also, it may take more like a month for the corals to completely acclimate. At least when I introduce new corals to my tank, I can pretty much count on them starting to grow at the 1 month mark.

Granted, they are also adjusting to new water params, new flow rates, etc...but it still may be relevant, especially in cases where signs of stress are apparent.

[Still Wet]

next time you do a bulb change hopefully not in 5 more years LOL but anyway try changing one or two bulbs at a time. wait a week and change two more. that usually works for me

[Dave Harms]

+1 to what has been said: stagger bulb changes and cut back photo-period at first, especially after changing SERIOUSLY old bulbs like that.