Should I rent a PAR meter for first tank setup

[puddleglum]

To what end? just knowing some number under some coral gets lower as it grows and produces more shade? What is the purpose?


Same light, same settings… yes the PAR measurement between the two is relative and can be of use to match things up. Different fixture or settings? Then we are back to less meaningful number. But, this is one area where they can be useful and is a far cry from PAR meters being needed or generally useful gear for most.


Correct, a wide range of the visible light spectrum. We can have 10 different lights with 10 different settings, all with the same PPFD readings… some will be good at growing corals and some will be terrible. It just depends on the spectral content and peaks.

I see what you are saying about the numbers themselves not telling you if a light is good for growing coral.

If one is working with a light that is known to have a good track record for growing corals, then would you see value in knowing the readings, at various locations and depths in a tank, of the intensity of a light that has a proven spectrum?

In the context of a newbie, like me, who has a high likelihood of making rookie mistakes, would having those numbers be useful for asking questions? If I report to people here "I have a Kessil A360WE, and there is a spot with PAR of 160 that I would like to put a coral, but there is another spot with a PAR of 100 that I also could put it."(assuming flow, proximity to other corals, and other criteria are the same) Do you think I could get meaningful feedback if either spot will be a better location?

Thank you,
-pg

 

[BeanAnimal]

I see what you are saying about the numbers themselves not telling you if a light is good for growing coral.

If one is working with a light that is known to have a good track record for growing corals, then would you see value in knowing the readings, at various locations and depths in a tank, of the intensity of a light that has a proven spectrum?

Not really, unless you are running the same settings as the person who gave you the numbers to reference….. but wait for it….

If you are running the settings that are working for them, why do either of you have to measure? You set the light at the same settings and height above the water/coral.

In the context of a newbie, like me, who has a high likelihood of making rookie mistakes, would having those numbers be useful for asking questions?

No. People will pretend (or convince themselves) that some magic number is or isn’t your problem. If 300 at some random spectrum isn’t enough, is 311 or 325? They don’t know.

If I report to people here "I have a Kessil A360WE, and there is a spot with PAR of 160 that I would like to put a coral, but there is another spot with a PAR of 100 that I also could put it."(assuming flow, proximity to other corals, and other criteria are the same) Do you think I could get meaningful feedback if either spot will be a better location?

No, but people will give you feedback anyway, as they are convinced those numbers are super important. Pretty expensive tool to tell you it is darker in the shadows.

There are uses for these tools, but (again) the vast majority of this hobby does not need one or gain any real benefit to using one.

 

[Ziggy17]

The disconnect is that the number really doesn’t say much about the quality of light or how accurate the reading was even if it did.

It is like putting a meter on your driveshaft and telling somebody how many RPMs it spins at…. Without gear ratio or tire diameter, the number really means very little.

Incorrect. In this case, the meter is telling you what your RPM is, not your speed. The difference between a good running motor and your con rods turning into taffy, in knowing your RPM, never mind the other components like cam bearings. So bad example.

Low, mid or high compared to what? The last thing anybody new to the hobby needs is to worry about some random PAR number. Top of tank high energy, bottom lower, shadows even lower.

Even new hobbyists should know what PAR levels are in their tank to properly place corals. If you know what the top is and the sandbed is, you can have a good idea what everything else is. Not exact numbers but you will have a good idea what the light levels are in different levels in the tank.

Some people measure 400 at the surface, and some people 800…. Both have wonderful coral and growth. What is “low” or “high”??


Compared to what?


Your corals did better with more light, in most case they usually do outside of extremes… but again, the PAR meter really doesn’t tell you that because it does not take into account the suitability of the spectrum. Your windex blue 400 PPFD and my crisp white 400 PPFD are nowhere near the same with regard to coral growth or health or coloration. The number is meaningless.

Not coincidence that my corals began to grow better once I learned that my sandbed was actually 5, not 50, and my top was 100 not 250. Adjustments were made, corals started to truly blossom. I over-guessed what the PAR was, and my corals weren’t thriving, just surviving. Without the meter, I wouldn’t have thought to increase the intensity on the lights as much as I did. I would have thought increasing as much as I did would have had my top at 450, but it didn’t. Again, helpful data for me.

And I took my spectrum from a BRS video that experimented with all the lights we generally use, and they experimented with spectrum, intensity (PAR) and light height to get the best spread to avoid unwanted dark spots and hit spots.

I understand the point you’re making, but information is always useful , it just depends how you interpret said data and apply it, or not, accordingly . To blanket say that this data is meaningless is false, and we should encourage hobbyists to gather as much data as possible.

Edited for spelling, grammar.

 

[SliceGolfer]

@puddleglum - Check your local reef clubs or FaceBook groups to see if someone has a PAR meter you can borrow. I often seen other hobbyists lending their meters out if it means you get to meet another reefer in the area, visit their tank, and share a cold snack.

I find a PAR meter to be helpful when setting up a tank, or anytime I see corals not looking well. Example: my Raja Rampage chalice was loosing color, but only the black rings in the coral. Everything else on the chalice, and all surrounding corals appeared fine. I couldn't pin it down. After measuring the area for PAR, I learned that I had inadvertently changed my light intensity and the coral was getting bleached. There isn't much visible difference in going from 20% intensity to 30%, but the chalice felt so.

It's a tool you will use once or twice when you get new lights or set up a tank. The rest of the time, that multi hundred dollar investment will sit in a drawer. I would say yes, it is a valuable and necessary tool.

I recall my prior LFS before I moved rented theirs out for $20 a day.

 

[Cichlid Dad]

Incorrect. In this case, the meter is telling you what your RPM is, not your speed. The difference between a good running motor and your con rods turning into taffy, in knowing your RPM, never mind the other components like cam bearings. So bad example.

This is a bad example. What does shaft rpm have to do with cam bearings ? And no drive shaft rpm does not tell you your rpm it tells you your drive shaft rpm only, which is controlled be transmission, rear gears and tire diameter. Just knowing shaft rpm doesn't tell you engine rpm, vehicle speed ect with out knowing engine rpm, transmission gear ratio, rear gears, tire diameter. It doesn't tell you the engine HP, RPM limit of the engine

 

[Ziggy17]

Incorrect. In this case, the meter is telling you what your RPM is, not your speed. The difference between a good running motor and your con rods turning into taffy, in knowing your RPM, never mind the other components like cam bearings. So bad example.

This is a bad example. What does shaft rpm have to do with cam bearings ? And no drive shaft rpm does not tell you your rpm it tells you your drive shaft rpm only, which is controlled be transmission, rear gears and tire diameter. Just knowing shaft rpm doesn't tell you engine rpm, vehicle speed ect with out knowing engine rpm, transmission gear ratio, rear gears, tire diameter. It doesn't tell you the engine HP, RPM limit of the engine

I misread his post, I thought he mentioned crank shaft.

Let’s not turn this into an engine debate. It’s about properly using PAR data.

 

[X-37B]

Well I have never needed one in over 30 years of this hobby but I have one. Maybe because I ran halides all those years.
When switching to all led, 3-4 years ago, and running several different brands the meter was helpfull to determine how high to hang the fixture. This way you know the general energy your corals are getting across all systems.
In my current large display I used it to get an even blanket of light across the entire tank.
Running 2 Photon 50's on said system the par meter was used to dial in the crossover light between the 2 to create a par map that helped overall distribution with little to no hot spots. Not sure how you would do that without one.
same was done on my smaller 30×24×16 system where 2 xr15's were not enoigh to create a even blanket of light. I added another and the tank now has a much more even coverage throughoit the tank. Again this helped with the crossover and how far to space the 15's for even distribution.
When I setup my first led system a local said AI primes wont grow coral. I did not have a par meter but chose 2 over 1 16's for my nano cube.
I have no idea how much par I was getting but I did prove that they grow coral as well as my halides were doing at the time. Within a year all my systems were led.

So do you need one, no, but as a referece tool they can be a worthwhile investment.
I have a few high end frags that cost more than a par meter, lol.
The 18" nano cube.

 

[BeanAnimal]

Incorrect. In this case, the meter is telling you what your RPM is, not your speed. The difference between a good running motor and your con rods turning into taffy, in knowing your RPM, never mind the other components like cam bearings. So bad example.

I think you missed the point and made my point at the same time. Wrong tool and wrong metric for the information being conveyed and weighed upon.

PPFD is mostly useless without other information. In the case of the PPFD measurement, spectral information as well as a valid target reference.

Even new hobbyists should know what PAR levels are in their tank to properly place corals.

You are not seeing the forest for the trees.

Can you tell me what "proper" par level is for any given coral? Don't forget to include specific spectral information (power at key wavelengths will do) and indicate what the reference target it.

Consider this simple spectral plot (Sanjay Joshi)

Both lamps were prolifically used in the hobby until they were discontinued. Both are output 125 PPFD. They have insanely different (not even close) spectral outputs and grew coral insanely differently, growth rates, coloration, etc. As insanely different that they were, they were both far closer to "full spectrum" (another misnomer and misused concept) than any LED fixture on the market today.

Likewise, I can show you plots of two different well know lamps with one being 80 PPFD and another being 200 PPFD and grow coral about the same. We can also look at countless examples of high PPFD lamps being absolutely blown away (growth, health) with lower PPFD lamps.

It is all about spectrum, not PPFD.

The point is, that you (and everyone else) has been misled into putting misplaced value in "PPFD" as a metric for the purpose of coral "placement", as if the actual value means anything. Also note the sun in the graph and its spectrum and "PAR".

If you know what the top is and the sandbed is, you can have a good idea what everything else is. Not exact numbers but you will have a good idea what the light levels are in different levels in the tank.

Again, what number is the target and why, exact or not. The sandbend will have less spectral power than the top of the tank...but we don't need a meter to tell us that.

Not coincidence that my corals began to grow better once I learned that my sandbed was actually 5, not 50, and my top was 100 not 250.

Respectfully, you did not need a "PAR" meter to tell you that you had no light on the sandbed. Likewise somebody with 4 300W halides over a 90 gallon tank does not need a PAR meter to understand that they are blasting the top of the tank with 5x more light than most successful reefers.

And I took my spectrum from a BRS video that experimented with all the lights we generally use, and they experimented with spectrum, intensity (PAR) and light height to get the best spread to avoid unwanted dark spots and hit spots.

Yes, a "par" meter or "lux" meter or your any cheap light meter (handheld or app based) show you relative "hot spots". Accuracy means nothing, just readings relative to each other. Far from being a must have tool for new reef keepers, or most in general.

I understand the point you’re making, but information is always useful ,

If the information is understood, maybe. The issue here is that the overwhelming majority of people in this hobby have no idea what the information actually means or how to apply it. The "PAR" reading is almost universally misconstrued as a meaningfull number in regard to what a coral "needs" and it is not.

Let's keep context here though. The tool is touted as "must have" daily on these forums and elsewhere. People are told that they can't be successful without one and that having one will make them more successful. It is hooey.

They have uses, for sure and are great for matching levels between multiple systems with the same fixture and settings. But, um... same settings and fixture and height... well then you don't need a meter :winking-face-with-tongue:

Back un the T5 and MH days, bulb degradation was a thing. The PAR meter could give you a pretty good indication of when your lamps started to degrade. Not needed, as timelines were pretty well know, but interesting. With LEDs this really is not an issue, at least to the extent that it is worth the purchase of a meter to check the 5-7 year emitter output.

Why do I spend so much time on stuff like this? My goal is to inform people and remove misinformation and misconception that spreads like wildfire in this hobby... as well as save people some money.

This is not a personal attack against your understanding, but rather an attempt to get people to take a half a step back and think about the big picture.

Yes I own several Apogee par meters.

 

[TangerineSpeedo]

Why do I spend so much time on stuff like this? My goal is to inform people and remove misinformation and misconception that spreads like wildfire in this hobby... as well as save people some money

Why don't you say then, "With the proper application and information Par meters can be useful, But without that, Par values can be erroneous. Until you understand the differences between PAR and PUR, Par values are just a number, and information that is gleamed from that is assumptive. No, IMHO I would not recommend a Par meter for a beginner until they have a rudimentary understanding of light, spectrum and how it affects your corals."
Or, I guess you do you...

 

[BeanAnimal]

Why don't you say then, "With the proper application and information Par meters can be useful

Because the use usefulness cases are rather limited, regardless of the popularity. My stance, based on basic fact if what PPFD is a measure of, is that most people don't need one and not that a bit more understanding resolves the issue.

Par values can be erroneous. Until you understand the differences between PAR and PUR, Par values are just a number, and information that is gleamed from that is assumptive.

That boils down the issue but does not provide that the PAR meter gets you closer to PUR in a meaningful way. Even if the average hobbyist was wielding a $30,000 state of the spectrophotometer, most would have no meaningful way to interpret the data other than "Ohh look bluer with some red peaks" kind of analysis.

We don't really have a way to measure PUR and to some extent it is not only coral dependent, but different wavelengths may have different overall effects with regard to what they drive.

No, IMHO I would not recommend a Par meter for a beginner until they have a rudimentary understanding of light, spectrum and how it affects your corals."
Or, I guess you do you...

More like: MHO I would not recommend a PAR meter for a most reef aquarists, beginner or advanced. Even with a modest understanding of light and spectrum, the PAR meter does not provide significant benefit with regard to proper light level or spectral information for growing coral. Those with advanced understanding, already understand this.

Me doing me? In this thread (and countless others) - people are told they must have a PAR meter to setup their tanks. It is absolute hooey.

 

[Formulator]

Back un the T5 and MH days, bulb degradation was a thing. The PAR meter could give you a pretty good indication of when your lamps started to degrade.

Ya, that’s why I use one! ;)

I’m still living out the glory days and will continue until they stop selling bulbs or someone pries my MH fixture out of my cold dead hands! :rolling-on-the-floor-laughing:

 

[puddleglum]

Ya, that’s why I use one! ;)

I’m still living out the glory days and will continue until they stop selling bulbs or someone pries my MH fixture out of my cold dead hands! :rolling-on-the-floor-laughing:

We need a "Come and Take it" shirt with a picture of a MH/T5 hybrid fixture on the front for you

 

[kyreefville]

I’m not informed enough to pose why or why not. Instead of renting a cheap par meter for 60 bucks I used the Photone app and paid $6 for 30 day upgrade. It gave a decent level of understanding of light readings at various spots in the tank and how moving light up down and intensity changed those values. Do I have a detailed spectral analysis? nope! And doubt I would understand one. But it made me feel good and cost less than a happy meal.

 

[puddleglum]

I’m not informed enough to pose why or why not. Instead of renting a cheap par meter for 60 bucks I used the Photone app and paid $6 for 30 day upgrade. It gave a decent level of understanding of light readings at various spots in the tank and how moving light up down and intensity changed those values. Do I have a detailed spectral analysis? nope! And doubt I would understand one. But it made me feel good and cost less than a happy meal.

Now that is interesting. Could get me in the neighborhood, help me get an idea of intensity to set the Kessil at, and let me know if I have any hotspots in the tank that I am not expecting.

 

[saullman]

I’m not informed enough to pose why or why not. Instead of renting a cheap par meter for 60 bucks I used the Photone app and paid $6 for 30 day upgrade. It gave a decent level of understanding of light readings at various spots in the tank and how moving light up down and intensity changed those values. Do I have a detailed spectral analysis? nope! And doubt I would understand one. But it made me feel good and cost less than a happy meal.

Agreed, I consider myself a novice to this hobby. I am running 2 x XR15's over a 4 ft Red Sea tank and my corals are struggling. I found out I had to turn up my intensity on my lights. At the same time I was curious about my par levels in my tank as I had never measured par before. I learned about the photone app to measure par. I know it won't be very precise like a Apogee will, but I just wanted a general idea. So I made a paper diffuser for my front camera (iphone 15 pro) and I already had a waterproof pouch for my phone. For just a few bucks I was able to have a general idea of what kind of par readings I am getting in my tank.

Btw- if you try the Photone app. Iphone users have to pay $$$ to use the different spectrums.
Android users can use the app and different spectrums for free.
Lucky me has both iphone and Android phones.

 

[Hooz]

Yes. Getting your hands on a PAR meter when setting up a new tank can be invaluable. You will hear people (mostly ONE person) talk about them being meaningless, etc., but here's the thing...

Most every LED reef light on the market from the $1000+ lights down to the $100 Chinese lights on Amazon have LED choices that put out useable light for coral (PUR). Are there some that are better than others? Sure. But, FOR THE MOST PART, even the "knock-offs" are dialed in pretty well, since they just imitated the "big names".

No. We don't know if a specific coral prefers 300 PAR or 286 PAR, but we DO know there are accepted "ranges" of PAR for certain coral TYPES. If you want a happy LPS tank, shoot for 50-150 PAR. For SPS try to land in the 250-350 range. There are exceptions to every rule, but you can set yourself up much better out of the gate if you have access to a PAR meter.

Now... I WILL say that LED "reef light" PAR does NOT translate to Metal Halide PAR or T5 PAR, because the overall output of each light type varies a LOT, as does the percentage of that light that is actually beneficial to coral. But, comparing modern LED fixtures and PAR readings provides useful information.

 

[SliceGolfer]

Btw- if you try the Photone app. Iphone users have to pay $$$ to use the different spectrums.
Android users can use the app and different spectrums for free.
Lucky me has both iphone and Android phones.

I paid for one month of premium use of Photone and found that their kelvin meter capped at 10K. Was hoping for better than this but maybe it's a limit of the iPhone or the app itself. The iPhone wasn't designed as a spectrometer and I'm expecting too much ;)

 

[BeanAnimal]

Most every LED reef light on the market from the $1000+ lights down to the $100 Chinese lights on Amazon have LED choices that put out useable light for coral (PUR). Are there some that are better than others? Sure. But, FOR THE MOST PART, even the "knock-offs" are dialed in pretty well, since they just imitated the "big names".

Is that an argument for or against? If a light is “dialed in pretty well” why does somebody need to measure it?

Now... I WILL say that LED "reef light" PAR does NOT translate to Metal Halide PAR or T5 PAR, because the overall output of each light type varies a LOT, as does the percentage of that light that is actually beneficial to coral. But, comparing modern LED fixtures and PAR readings provides useful information.

You lost me there. Are you saying that LED spectrum does not vary a lot from fixture to fixture or over infinite adjustment of settings on the same fixture?

 

[Hooz]

Is that an argument for or against? If a light is “dialed in pretty well” why does somebody need to measure it?


You lost me there. Are you saying that LED spectrum does not vary a lot from fixture to fixture or over infinite adjustment of settings on the same fixture?

I am saying that here is the spectrum (all channels at 100%) of a popular, PROVEN, $1000, 215w LED reef light.

And here is the spectrum (all channels at 100%) of a new $100, 30w Amazon LED reef light.

I feel like the spectrums of both lights are pretty darned close, and the "proven" light has grown hundreds of thousands of coral frags an colonies in just about every coral farm there is... so "PUR" is not an issue with either light... They're not identical, but I'm confident that any idiot can take either light out of the box, put it over their tank, turn it on and be satisfied that the "PUR" will grow coral.

Agreed?

So if, as I posited before, modern LED reef lights have the "PUR" part covered, then the only thing left for us to really "dial-in" is intensity, right? Height, spread, overlap are all functions of intensity, and the only accurate means of setting that is with a PAR meter.

 

[BeanAnimal]

I am saying that here is the spectrum (all channels at 100%) of a popular, PROVEN, $1000, 215w LED reef light….
I feel like the spectrums of both lights are pretty darned close…
Agreed?

…then the only thing left for us to really "dial-in" is intensity, right?

The spectrum between these two lights is not “pretty darned close,” even if it seems so at a glance. Moreover, most people are nowhere near running all channels at 100% anyway.

PUR is not just automatically "covered" by any modern LED light. PUR is a subset of PAR, and it’s a scalar value tied directly to the spectrum. Because every fixture has a unique spectral output, PAR numbers don’t offer what you think they do. That has been the point all along.

Will both grow coral? Maybe. That does not mean they will do so the same way or that the PUR is the same.

You can’t assume two lights with different spectrums but similar PAR readings will have the same effectiveness for coral growth. Even small differences in the spectrum can lead to significant differences in PUR. While intensity is important, relying solely on PAR meters to "dial in" intensity overlooks the fact that these meters don’t measure the efficiency of the spectrum itself (i.e., PUR). This is why the PAR numbers between these fixtures can’t be compared meaningfully if the context is coral growth or health.

Your fixtures above. 215@w and 30w - do we need a PAR meter to figure out that 6 or 7 of the small ones put the same power as the big one? If they are not the same spectrum (they are not). What is the PAR meter telling us. If we both run them at different channel settings, what is the PAR meter telling us? Those are rhetorical questions, no need to answer.