Clueless on PAR

[H2oheartny3]

Hi I have a 105G frag tank. It’s about six months old. All parameters are good and are stable. So far I’ve added about 10 coral frags in the last month or two. Some seem to do well, some of the sps are growing, but the polyps are not extending. What would be the cause of this? I’ve tried messing with flow, made sure my water is stable, but they’re not extending… could it be lighting? I have 2 xr15 blues, running AB+ template 12 hours a day at 50% intensity. Like I said it’s weird, you can see the coral growth, they’re just not happy and extended. Any tips?

 

[BroccoliFarmer]

Have you rented a par meter to actually measure the par? 50% intensity on AB+ is a good start...but how far above the water is the light...how deep are the corals in the water. These are factors that will affect how much light is (is not) reaching your corals. Not extending to me sounds like TOO MUCH light as opposed to not enough..but again, I dont want to guess unless I know more.

 

[gbru316]

No need to rent/buy a PAR meter. There are apps for Android and iOS that are close enough to work just fine for our purposes.

See this post (and the thread it's contained in)

 

[homer1475]

Polyp extension has nothing to do with coral health.

Ever wonder how vendors get those shaggy picture? Stop the flow so the coral has to extend it's polyps to exchange gasses.

Tank inhabitants, and flow could also limit polyp extension.

Before I bought my lemon peel angel, my sticks were relatively furry. I have never seen the angel nip, but they are known for it. It's the reason I have 0 PE except at night when the angel is sleeping.

 

[H2oheartny3]

Have you rented a par meter to actually measure the par? 50% intensity on AB+ is a good start...but how far above the water is the light...how deep are the corals in the water. These are factors that will affect how much light is (is not) reaching your corals. Not extending to me sounds like TOO MUCH light as opposed to not enough..but again, I dont want to guess unless I know more.

I can rent one? Any suggestions on where?

 

[H2oheartny3]

Have you rented a par meter to actually measure the par? 50% intensity on AB+ is a good start...but how far above the water is the light...how deep are the corals in the water. These are factors that will affect how much light is (is not) reaching your corals. Not extending to me sounds like TOO MUCH light as opposed to not enough..but again, I dont want to guess unless I know more.

No need to rent/buy a PAR meter. There are apps for Android and iOS that are close enough to work just fine for our purposes.

See this post (and the thread it's contained in)

An app for iOS that measures underwater PAR? App name?

 

[Mr. Mojo Rising]

I can rent one? Any suggestions on where?

Ask your local LFS, many rent out PAR meters

 

[gbru316]

An app for iOS that measures underwater PAR? App name?

Photone. The app is free but there’s a small fee associated with the LED spectrum option. Still significantly cheaper than a dedicated PAR meter.

 

[damsels are not mean]

What are the inhabitants of the tank?
What does the coral do at night? Polyps out or in?

 

[Tathamet]

Photone. The app is free but there’s a small fee associated with the LED spectrum option. Still significantly cheaper than a dedicated PAR meter.

I heard from an android user that all the features are free on android for Photone. It’s just iOS that you have to pay to unlock the led feature.

 

[Koh23]

Not direct on topic, before i used photone for android, recently i downloaded it again, and have very strange, almost impossible readings....

For example, under 165w black box, 24" at bottom, i get 25par reading, on water line, 8" below lights, with 90 lenses, i get about 250-300 par.

Under 90w rs90, all channels at full, i get about 300 par, few inches below water line, maybe 150, and at bottom maybe 15-20 par...

Not sure why, but these readings seems impossible

 

[H2oheartny3]

Ok so I rented a PAR meter from my LFS. Seems my PAR was WAY lower than I thought. Could too low light cause polyps to not entendres?

 

[Bpb]

I'm afraid that guessing par on one tank based on manufacturer data is the equivalent of guessing your alkalinity based on what your salt bucket says. You absolutely cannot and will not know your par levels to any degree of accuracy at all without actually checking using a decent meter. Your own water clarity, geometry of your rocks and tank, manufacturer variation in the lights themselves, and most of all varying height above water and distance between fixtures can all have massive impact on your par levels.

 

[Koh23]

Allow me to stir a sand little bit

Why i must know exact par? I mean, dont try to say that this information is not inportant, just saying that is not that important.

I saw too much reefs, great looking ones, with all sorts of corals, clams, running on all sort of lights, mh, diy led, t5, comercial led... And not a single person have par meter, or some clue about par levels. At best, we played with lux meters, not calibrated, not even suitable for underwater....

And nobody cared. Corals will adapt. Personaly newer seen dead coral from light. Nobody can tell me that softie cannot be directly under 90 or 150w led, few cm below water. It can.

If your main goal is high end sps, sure, rent a meter, if u can. Here, i dont have that option. Otherwise, set your lights to what seems right, and u will see, if corals dont react good, turn it on a bit. Or set it lower, but, i really have hard time believing that 20% is light setting for reef tank