too much par?

[slammin]

Hey guys/gals,

so i finally got a hold of a par meter last night and tested out my tank. I've had this feeling that i am blasting my sps with too much light for awhile now.

I've bleached a few very nice montis, and my red planet went completely white (polyps still come out). thing is it take a few months for them to bleach, so i didn't catch on right away. i think what made me realize was a purple plate that fell onto my sandbed a couple weeks ago, and now has a nice growth ring.

anyway, here are my numbers:

i'm getting 200 on the sandbed just about everywhere, and the top of my liverock structure is getting 400-600

my lighting 3.5" above water line, and is a 6 bulb ATI powermodule with only 4 bulbs on (one ballast burnt out, bulbs are coral +, purple +, 2x blue plus) and 2 reefbrite led strips (front and back of fixture).

is this too much par? what can i do to lower it? replace the blue + with actinics? i can;t really raise the fixture and i keep a skirt around the light to minimize light spill into the room...

whats the ideal par numbers i would want on the top of the rock structure? 2-300? and 50-100 on the sand bed?

 

[karsseboom]

Nope that's perfect. I have the same light and the same par numbers.

 

[gbru316]

Water movement plays a role in the amount of light a coral can tolerate.

Feature Article: Water flow is more important for corals than light. Part II: The science of corals and water flow

 

[slammin]

really? good to know, maybe i'm just not acclimating new coral to the light correctly? i have had a few sps frags on the sand bed for the last week that are doing great (held colour and good polyp extension), but i'm afraid to mount them higher up without light shocking them..

i think i have lots/good flow. i have 2 mp10's running, both at almost max (one on reefcrest/ one on lagoon)... my tank size is 24x24x18.

do you think my numbers are acutally higher than the par meter reads? i remember reading that royal blue leds read lower then they actually are...

thanks for the input guys...when i get a chance (probably the weekend), i'm going to test the par on a 250w halide (electronic ballast and luminarc mini) and a ecotech radion (gen 1 no tir) over the tank, very curious to the numbers...

 

[jerpa]

The apogee meter reads all blue light lower than it should. The difference is only about 20% and is only applicable to the light generated under 500 nm. You may have slightly higher, ~5-10%, PAR than the meter reports but you can have larger errors based on how you held the sensor.

That's my long-winded way of saying you can trust those numbers.

 

[nvdiz]

I failed

thanks for posting the par numbers with 4 lights.

I have the 6x24w and have been wondering about the possibility of bleaching my corals as well.

 

[slammin]

its a 6x24 Ati Powermodule with 2 24" reefbrite strips on either side of it..one ballast burnt out, so i'm only running 4 of the 6 t5 bulbs.

here is another pic of the light: