Reducing photoperiod

[newfound77951]

I'm thinking of cutting back on the photoperiod in my 30g (36x12x16) reef tank; some of the lower light corals (mushrooms, especially) are not too happy with the light right now, while the rest of teh corals are very happy, so i dont want to 'upset' them. Currently the lighting is 4x39 watt T5s, 2-10000K and 2 actinic. The actinics are on from noon-11 PM and the 10000Ks from 1PM-10PM. My questions are: how fast/slow should I cut back the light, and what might be a good target photoperiod to shoot for?

[lando]

Is this a new fixture? If so, your lower light corals will need to be photo-acclimated. There is a good article in our "Articles" section about this. Cutting back would not hurt. You can safely do it by a few hours if you want. Or just keep the actinics the same and alter the photoperiod of the daylights

[melosu58]

This is one of those questions that will have many answers. I have my actinics on from 9A-9P and my 50/50 from 10A-8p.

[newfound77951]

It is not a new fixture, well, the tank has only been set up since Feb, so i guess it is new in that sense. I am having some algae (macro and cyano mostly) issues and noticed that the shrooms don't seem to be as happy as they should.

[melosu58]

Originally Posted by newfound77951

It I am having some algae (macro and cyano mostly) issues and noticed that the shrooms don't seem to be as happy as they should.

We need to find out what is fueling the macro and cyano.. Check out the nitrates and phosphates and lower your lighting period for a week or two to help get rid of the cyano. The macro will have to be removed manually. Here is an article on cyano.

http://www.aquariumadvice.com/articl...q=2&fldAuto=48

[lando]

I agree. The algae issues are caused by more then just the lighting. Cutting back on photo-period will certainly help with you identify and correct the root problem. FWIW, shrooms are pretty forgiving in regards to lighting. Judging by the size of tank and amount of light, I would turn your attention towrd water parameters issues for your coral's unhappines. I do not think the light is the issue. Good luck as you investigate this.

[newfound77951]

I just checked nitrite, nitrate and ammonia and they were all zero. The tank does get a little sunlight in the afternoon and I am wondering if this is part of the algae problem? It also seems like it is the low-light corals that are unhappy while the higher light corals are fine. I recently moved some of the mushrooms into the shade of a branch rock and they perked up noticeably.

[lando]

PO4?

[seaham358]

check phosphates... Cyno feeds on that. And high PO4 does effect corals.

[newfound77951]

Forgot to mention that one....also 0. Test kits are all pretty new. I use the AP SW master kits for NO3, NO2 and NH3, SeaChem for PO4.

I just shortened the 10000Ks by an hour, will wait a week or so and shorten another hour. I think I need a sheet or screen to keep the sun out of the tank, it gets direct sun for about an hour, I think, in the afternoon. I'm not usually home at that time so I dont know exactly how long it is.