Par Meter = More confusion

[ReefBeez]

I recently got a Par meter and was interested in opinions on what the heck is going on.

Lighting is a 60W Razor Nano 16k that is 12 inches over a 24"x 24" x 12" deep tank.

Ive had this light at 40% "white" & 45% "blue" for months now.
Peak for 4 hours and ramp up/down for a toal of 12 hours.

I have LPS, and an anenome that had all been doing well. I also have a monti that has done well. Whenever I have tried to increase light, I get bleaching of the monti and my zoas recede. Even with minuscule increases. The hammers seem to do better, the higher the light.

I got an Apogee SQ-520 to measure my par. Par readings at bottom of tank at those setting are 5 (umol m2 sec) and maybe 40 if cranked up to 100%.

Any help in interpreting these numbers. I was hoping to get some Par info so I can position my corals in areas with more appropriate light.

My assumption is that the meter must be reading low as the corals have been doing well at this setting. From what I have read, I understand that no Par meter is a perfect measure of light but that this meter is supposed to give a decent estimate with LED lights.

 

[gus6464]

For the SQ-520 you have to multiply your reading by 1.32 to account for refraction of water to get the real number. Also those readings are very low no matter what so there is definitely going on with either your light or par meter.

 

[ReefBeez]

I do have the immersion correction turned on which does adjust for the 1.3 you described.

 

[Ron Reefman]

Have you tried taking a reading near the surface? What do you get? It should be around 250 to 400.

Also consider taking it outside on a full sun day at noon and you should get 1200 to 1400.

If not, there is something wrong with your meter.