Par testing and target numbers

I was just curious if there is a certain par range that will not only improve coral growth but also the color. I just recieved our clubs par meter and am testing my lights. I have a 6X80w T5 setup, 2 4X80w setups, and an LED w/T5 supplement setup. So far I have tested my 3 T5 setups and am somewhat surprised at the results, now I have to take everything apart and re-install the LED/T5 setup and test that. As of right now here are my results.

100g tank, all T5 lights are 9" off the water surface. I took readings just below the surface, midway down, and at the bottom. Midway down is 9" from the water surface and the bottom is 17" from the surface.

LED w/2X80w T5

Surface-580
Midway-252
Bottom-220

6X80w T5
Surface-611
Midway-330
Bottom-262

4X80w T5(setup 1)
Surface-407
Midway-232
Bottom-201

4X80w T5 (setup 2)
Surface-370
Midway-206
Bottom-194

What are your thoughts on these numbers? Any help or sugeestions would be appreciated.

 

It's tough to assign general number to being "good" or "bad". Corals come from all sorts of depths and water conditions, with all sorts of lighting and have adapted accordingly. You can't really say what's good for a shallow water coral is good for a deepwater coral, or even a mid level coral. Also, there are lots of other factors, such as flow, nutrition, trace metals that have an effect on how identical corals will tolerate or respond to light in different environments.

To overly generalize, a bit, it looks like good "SPS" numbers. There are exceptions, some SPS like a lot more and some like a lot less, but 200-500 is usually good target for a lot of SPS (at least acros - some montis, for example, may bleach out at that range, if not acclimated carefully). Many Soft corals will probably also tolerate that range, but some will like less. Some LPS corals may tolerate that range, but many will be quite stressful to many. Some LPS such as war-coral favia, acans, chalice corals etc... seem to often have trouble with much over 100 IME. However, that can be very different for a given coral. Some chalice corals for example, actually like a lot more. Really depends on the coral, so, these are very general recommendations...