What do you trust? Par Meters or Eyes?

[revhtree]

Thank you to @Sleeping Giant for the QOTD idea!

When it comes to measuring lighting for your reef tank the most common tool available is a PAR Meter. But just because you can "measure" your lighting doesn't mean that you will automatically know what amount of light is best for your particular reef tank. For that you need to factor in many things like tank dimensions, types of corals and other variables. So what is a healthy amount of light for your reef tank? Do you trust the PAR meter or your eyes? Let's talk about it!

When it comes to knowing what the right amount of light is for your reef do you go with what a PAR meter says or what your eyes see?

Please explain your answer and why you choose one over the other.

image via @HKAVR45

 

[Reef and Dive]

PAR meters for sure! Our eyes are perfectly made to fool us.

But… there’s much more than just par: coverage, distribution, spectrum and ramp configuration seem to matter a lot to me.

 

[Waters]

Well, PAR meters initially.......but every tank is different. If the coral aren't responding to the "ideal" PAR levels, then I change them.

 

[alton]

PAR meters for sure! Our eyes are perfectly made to fool us.

But… there’s much more than just par: coverage, distribution, spectrum and ramp configuration seem to matter a lot to me.

True and that Par meter can tell you where you have coverage, and where you don't. So many times aquarist will have one coral doing great, while another not so well 4" away. Then they use a Par meter and find out the Par level at the second coral is must lower than the first. Our eyes cannot tell when a lamp or LED is going bad. This happened to me many years ago with MH lamps. My corals started looking poorly only after 6 months, went back with a meter and they had dropped 50%. I never used those lamps again.

 

[BroccoliFarmer]

Whatever BRS Investigates tells me to?

 

[PeterC99]

There is so much that the naked eye can’t see and gauge.

Get a par meter and your eyes will be opened!

 

[blaxsun]

Neptune PMK for the win!

 

[Forty-Two]

Its a pretty essential piece of gear IMO. That being said it's not data that is going to immediately solve your problems for you.

While you do get the PAR data - which is very helpful - most corals are on a range. I have a favia that I think is allergic to light. Even though the PAR is around 50-60 - and that should be ok for the species - really it probably prefers 30-40.

What Im trying to say is PAR meters will help you troubleshoot the problem and figure out what PAR the coral is in - but you still have to learn to read the coral in terms of what it wants.

 

[MabuyaQ]

I said other because you need both. A PAR meter can tell you how much light there is but you gone need to use your eyes and look at the coral to assess whether or not if it is the right amount and at what spectrum for long term coral health.

 

[Dkmoo]

Par for sure. After I got a par meter a couple of years ago, I have had 0 frag loss from introduction and acclimation to my tank.

 

[Reefin Aint Easy]

Whatever BRS Investigates tells me to?

And we found out from BRS that even some pros couldn't tell the correct par with their eyes.

 

[HeyLookItsCaps]

I picked other because I’m super proud of myself. I rented a par meter because I keep hearing about them, but I have always used my eyes in the decade + I’ve reefed. I was SHOCKINGLY spot on. So I used a par meter to confirm my eyes, and now I have my “prescription”.

 

[DeniseAndy]

I used a PAR meter many, many years ago to test my lighting. I gauged about where everything was. Then, I rebuilt the tank completely. However I still use MH and T5 lighting and figure the PAR must be close to way back when since still same lighting.

I mainly use my eyes to gauge how the corals are doing and adjust as needed. I rely on the corals to tell me. Not my view of the lights.

If I had the energy to do a PAR reading (or the ability to - no meter) I would use it to get a good gauge again. Mostly for curiosity.

 

[Koigula]

4 54W t5 bulbs and 2 250 halids radium for main tank.

8 54 w T5 on frag tank and done.

I sold all ecotech and done with them.

 

[redfishbluefish]

Normally I'd simply say PAR meter. However, I found it hard to justify 300-400 dollars for a piece of equipment i'd use for ten minutes. Fortunately an R2R member, @saltyfilmfolks , was extremely knowledgeable and did a fair amount of testing to come up with the correction values for using an inexpensive LUX meter. I was willing and ready to spend 15-20 dollars to dial in my lights....and it worked perfectly.

 

[LRT]

Whatever BRS Investigates tells me to?

They definitely nailed it with photon v2+ reccomended settings. Id reccomend anyone running a led that brs has done the work on to give the settings a shot. They won't be disappointed. With a 50/50 blend of whites and blues it should make most folks happy.

Par meter for me all the way. From there I try to find sweet spot for my corals. The guidelines help keep things safe.

 

[BaghdadBean]

PAR meters are pretty darn essential, but you still need to watch your coral to see if they’re responding well to your placement of them. I thought about just renting a par meter during the aquascaping part of the build, but decided I would rather purchase one used since they come in handy at several points over time, and I live in a remote rural area. Not a lot of access to equipment out here. I don’t really see PAR measurements as a set and forget thing, since it’ll change as corals grow and shade each other out, as lighting systems break in or break down, or even from changes in water quality and clarity. Watching your corals closely is a great indicator of how they’re doing, but parsing what is affecting polyp extension and so on might take more than blind guesswork. That said, I spent a lot of years prior just gauging light needs by coral growth rate and type, so I had to vote other. They’re a vital tool if you have them, but observation and experimentation are pretty vital too.

 

[Crustaceon]

It depends. We use the par meter to gauge par values. We use our eyes to gauge aesthetic value. You can have great par, but really terrible coloration. We really need a par meter and our eyes to achieve a good balance. That being said, I can tell with my eyes whether or not my tank has enough par. I have no clue on exact numbers, but I know it’s enough.

 

[James_O]

My eyes! Never had/used a PAR meter.

 

[NoahLikesFish]

eyes, if my corals dont like their lighting, then they can die. i dont want to blind myself and my cat. i already removed the light in my room because my tank is brighter than my room light