Upgrading from two to three Radion G5 XR15 Pro fixtures

Geventh · Jun 18, 2021

Hey guys,
Last year I bought two XR15 Pro fixtures and I'm really happy with them.
My Acros on the top are starting to shadow themselves and so I ordered another fixture.

Tank: RedSea Reefer 425XL (Mixed-reef)
Currently running the two fixtures at 90% intensity. (and the fans sometimes do get noisy)

Once I install my third fixture, should I start all three at 60% intensity and go up from there to maybe 80%?
I'm kinda trying to linearly scale the par values from the BRS data sheets for 2 / 4 fixtures.
At 80% I should be in the 300 par at the top half and under 200 par level bottom half? Does that sound reasonable?

I just don't want to shock my acros (top half) and my LPS (bottom half).

Thanks for the replies!

lazlodawg · Jun 18, 2021

I would just rent a par meter and take the guesswork out of it. It cost me 15 bucks for a one day rental from my LFS when I made lighting changes. Not directed at you OP, but I'm always surprised how someone will spend hundreds to thousands on coral and take risks that could be avoided for just a few bucks.

Geventh · Jun 18, 2021

lazlodawg said:
I would just rent a par meter and take the guesswork out of it. It cost me 15 bucks for a one day rental from my LFS when I made lighting changes. Not directed at you OP, but I'm always surprised how someone will spend hundreds to thousands on coral and take risks that could be avoided for just a few bucks.

I agree but here in Switzerland / Europe?
it's all kinda place/move corals and monitor until the corals are satisfied. Have yet to find a store here where they measure par numbers.

And buying a par meter for over 600$ is not in my budget. (which I will maybe use once)
I would have to convince my LFS to first order and then make it rental...

Hope someone else with three XR15 can share some light.

lazlodawg · Jun 18, 2021

If you are simply trying to match the intensity of the current two fixture setup with three fixtures to start with, could you just use a lux meter app for your phone? It sounds like the current light intensity and spectrum is working well for you and you only want to increase coverage and reduce shading so a lux reading could give you a good idea of where you want to be and reduce your margin of error.

Geventh · Jun 19, 2021

lazlodawg said:
If you are simply trying to match the intensity of the current two fixture setup with three fixtures to start with, could you just use a lux meter app for your phone? It sounds like the current light intensity and spectrum is working well for you and you only want to increase coverage and reduce shading so a lux reading could give you a good idea of where you want to be and reduce your margin of error.

Nice, I will try that out.
I assume I will measure lux value above water level at multiple points to get a rough idea?