PAR versus Photoperiod

[Makenna]

A quick question for you all and perhaps some experience.

I am in the process of moving around some corals to different tanks and one of the variables will be lighting. Many of these Corals, mainly SPS, are currently in a 12" deep tank lit with 2-250W MH 8" off the surface. The PAR as you would imagine is quite high but the Halides are only on for 5 hours a day and growth is strong (tank has been running for 4 years).

I am moving some of these corals to a 30" deep tank lit with T5's and LED's. The PAR will be adequate to support the coral, but certainly not as bright as the halides over a 12" depth.

The question is, Can the increased photoperiod of say 8-10 hours versus the 5 of the halides compensate for the decreased PAR.

Thanks in advance for your thoughts.

 

[mike_cmu04]

It should help because they will be exposed to more light throughout the day

 

[camaroracer214]

yeah, the increase in photoperiod will help. however, you will still get color changes and you may have to keep relocating certain corals to get them in the ideal spot. this is really unavoidable when changing to a different lighting setup.

btw, are you actually testing your par or making assumptions as to what the par should be in certain areas? i'm just curious because a lot of the time you'd be surprised at the par levels at various depths and distances away from lights.

 

[Makenna]

yeah, the increase in photoperiod will help. however, you will still get color changes and you may have to keep relocating certain corals to get them in the ideal spot. this is really unavoidable when changing to a different lighting setup.

btw, are you actually testing your par or making assumptions as to what the par should be in certain areas? i'm just curious because a lot of the time you'd be surprised at the par levels at various depths and distances away from lights.

Thanks for the feedback. yep, I am using a PAR meter and not neccesarily trying to make it exactly the same. As you mention, there are a ton of other things that will make the coral adjust.

 

[ruprecht]

The question is, Can the increased photoperiod of say 8-10 hours versus the 5 of the halides compensate for the decreased PAR.

Compensate for what is my question. In a very general sense, less intensity will increase pigment. More pigment with longer light period could equal less pigment with higher intensity. As you say there are a ton of things that are involved in the the balance between photosynthesis and coral health/growth and it will take your coral time to adjust. Will they adjust? My guess is yes. Will growth be as strong? After four years in a 12" deep tank I would assume you have fragged as few times? As flow is a main contributor to growth, is flow in the new tank equal or better? I could go on but I have a feeling that you know what you are doing and you get my point. Coral are resilient, just keep your water tip top and I am sure things will work out fine.