How do YOU Par map?

[Dburr1014]

I will bite:

Keeping in mind that two fixtures with wildly different spectrums but the SAME "PAR" (PPFD) for a given spot in a tank will grow the same coral vastly differently...

What is exactly is "fixing your PAR"?

How were the "target" numbers derived?

Hows was the specific spectrum that correlates to the "target PAR" chosen?

How do you account for coral growing and the PPFD at all (any) areas of the tank being in a constant state of change (coral growth shadowing other corals and its own growth).

Sometimes we create false correlations because they feel and sound reasonable... when in reality we just got lucky :)



Take a look below:

Those two lamps (both great lamps) are worlds apart with regard to spectral output. They happen to have the same PAR (PFFD) readings. Without question, two tanks full of the same coral in each will have VASTLY different growth rates and coloration under these lamps. The real kicker is that some coral may thrive in one tank and some in the other....

Image courtesy of Dr. Sanjay Joshi as part of his Metal Halide lamp database and discussions from a dozen or so years ago....

I fully understand what your saying about par meters, the over-use of them and the whole different spectrum of each unit.

However, I have also heard the human eye can not detect visually how bright light actually is. 100 par can look like 400 par.
I have seen countless threads where the light does not have the par to sustain coral or the user didn't turn them up high enough because they were afraid to burn the coral.

In my opinion, it is a useful tool to at least know where you stand for par or brighness if you will. Even checking a light after 5ish years to see how it's degrading, in my mind, is useful. I won't talk about spectrum here. We all know spectrum debates can go up in flames.

 

[exnisstech]

I test during peak intensity but my peak isn't that much higher than my starting intensity not counting ramp up and ramp down. I check with flow on and off just because I can but I record the results with flow on. I just pick a number between the high and low I'm getting and use that.
As useless as some think a par meter is I have no regrets buying mine. For years I failed at keeping clams alive long term and measuring par told me why, it's because I was starving them. What looked like a lot of light to my eyes wasn't. Even though corals grew well clams would perish after a few months. After measuring par and adjusting my lights I can now keep clams alive so I find a par meter a useful tool have.

EDIT: having a wand to mount the sensor to is a must have IMO

 

[BeanAnimal]

Your premis seems accurate but I think the reason is the sensor is not as accurate with flow on so you're not getting a true reading from the sensor. The actual par to the coral is probably the same with flow on or off but not for the sensor.

If light is being reflected and refracted by the ripples in the water and this causes the sensor to read different values, then the photo receptors in the zoox are going to be affected the same way... are they not? Coral don't have focusing lenses or collectors :)



Sure we can get into the details of the sensor and its cosine correct, but that would be splitting needless hairs -- as the actual angle of the lens with regard to the light source makes FAR more difference and the overarching reality is that the numbers returned (flow on or off) have no real reference due to spectrum and meter differences -- therefore the returned values (whatever they are) are or arguably meaningless for most contexts to begin with.

 

[keithw283]

Your premis seems accurate but I think the reason is the sensor is not as accurate with flow on so you're not getting a true reading from the sensor. The actual par to the coral is probably the same with flow on or off but not for the sensor.

Yeah I could see that. I've always done it with flow on. tbh it seems par requirements for coral are pretty overblown. I bought my meter early in my reefing career and kinda wish I hadn't wasted the money. The corals will tell you if they are happy or not.

 

[BeanAnimal]

However, I have also heard the human eye can not detect visually how bright light actually is. 100 par can look like 400 par.
I have seen countless threads where the light does not have the par to sustain coral or the user didn't turn them up high enough because they were afraid to burn the coral.

You are correct in terms of the human eye in general. Add in the spectral variance and it is useless.

A few basic points to consider.

1 - any modern fixture run at a reasonable spectrum and intensity is going to work.
2 - with few exceptions, it is hard to have too much light.
3 - even if we can measure PAR, it tells is nothing useable about needed spectrum.

It is my opinion that choosing a known working spectrum (copy what works for somebody else, and don't try to tune your own at first) is far more beneficial than trying to use a PAR meter and correlate the numbers to anything remotely useable.

We know that any reasonable T5 or MH setup grows corals and we know that the first gen (really low output) SOLARIS and RADION fixtures grew coral.... Spectrum matters a lot... PPFD is all over the map and an undefined tail to chase. :)

5ish years to see how it's degrading,

I would suggest that a free lux meter app for your phone would serve the same purpose :)

I do own an Apogee 510, and have had several others here over the years. I too, at one point thought that it was a must have "instrument" until I really thought about it and applied basic engineering and logic.

Think if it is a calorie counter for a diet - but it does not know the difference between fat, protein or carbohydrates, let alone that is is not accurate to within say 30% or so of the actual caloric content anyway. Not something useful for diet planning, even if it feels like it should be and every influencer in the space uses one and every dieter has one.

Just some food for thought (no pun). Thanks for the response.

 

[twentyleagues]

I find using a parmeter useful with leds. In the past I had 2 tanks one 125g sps dom the other a 120g euphyllia dom. I had 250w mh over both with t5 actinics both standard tanks a 6' and a 4'. The 6' 125 had 3 mh and the 120 had 2. I have no idea the par output of those tanks, both grew corals both tanks lights were 12" off the water. We didnt have par meters readily available.

When I got back in everything had changed. Leds can be deceptively bright or dim looking depending on color, fixture, beam angle, wattage, what have you. Point in case I have a 4' led t5ho replacement grow bulb I use over a fw tank. I typically get a bulb that is very crisp white with like 10% of the total leds being blue and 5% being a "uv" led. These have become very hard to get so I got a different one all same led just white was supposed to be 6000k looks warmer and much brighter than the other light still a grow light intended for "plants", same manufacturer. I took par readings of the old bulb a while ago and tested the new bulb thinking it may have more "par" because the lack of blue and "uv". I was wrong the avg of the old bulb was 75 the new one while it visually looks brighter and definitely warmer its avg is only 50. It does not grow the plants the same but really grows algae like a champ. I was thinking color spectrum at first, could be part of the reason.

The wand does help with mapping as it holds the sensor steady. Its then up to you to hold a proper angle on it to the lights. Make a grid of the tank in both up and across take reading at sandbed, mid tank, and a couple inches over the tallest rock structure front to back. This will give you a rough idea of the light intensity at those points. I do it with the flow on as water movement at the surface will cause the light to shift. ( cant remember if its correct terminology is refraction).
We have at our finger tips (internet) what reefers have found a vast array of par numbers that will grow corals.
Basically just make sure its not to low or to high as leds are deceptive.

 

[Lavey29]

Yeah I could see that. I've always done it with flow on. tbh it seems par requirements for coral are pretty overblown. I bought my meter early in my reefing career and kinda wish I hadn't wasted the money. The corals will tell you if they are happy or not.

Yes most experienced reefers will say the corals will tell you but a few years back my corals were stagnant. I was going off recommended settings for my XR15 lights and tank dimensions. I rented a par meter and was shocked to find out how low my par was even though all the internet posts said my lights should be at 50 to 70% intensity. I slowly increased to 100% intensity and bam, the tank exploded with coral growth and color.

 

[X-37B]

Get or make a wand for your meter.
Test with the in tank flow on.
Don't worry about the actual number as it will vary depending on how you hold the wand. Just get a routine on how you take your measurements and repeat it.

Par #'s are, imo, beneficial in understanding how much light your getting across your system.
The actual number is a reference point I use so I know where I started. When I increase the power the numbers go up.
To me the number is what it is and I adjust based on observed coral growth.

When setting up my system I start at 200 par across the top of the rocks. I use the par meter when I turn up the lights.
Different lights give different results so saying par of 200 is needed is not really relevant, imo.
I am at 300 across the top with the uv/v or4's off. When I tun them on I pick up another 75-100 par across the system. System is at 400ish par across the top of the rockwork.
The system is 1 year old this month and doing well.

 

[X-37B]

Yes most experienced reefers will say the corals will tell you but a few years back my corals were stagnant. I was going off recommended settings for my XR15 lights and tank dimensions. I rented a par meter and was shocked to find out how low my par was even though all the internet posts said my lights should be at 50 to 70% intensity. I slowly increased to 100% intensity and bam, the tank exploded with coral growth and color.

Yea I ran and still run the xr15's. AB+ at 100%. With 4 on my old 80 growout I was getting 200 par at the bottom, which was 12.5" and this system grew coral real well.
I had 5 when I moved and set up a 30x24x16 with 2, and then I added 1 more. This gave me an even blanket of light across the system.
I do like the spectrum of the ab+ and the colors it brings.

 

[Lavey29]

Yea I ran and still run the xr15's. AB+ at 100%. With 4 on my old 80 growout I was getting 200 par at the bottom, which was 12.5" and this system grew coral real well.
I had 5 when I moved and set up a 30x24x16 with 2, and then I added 1 more. This gave me an even blanket of light across the system.
I do like the spectrum of the ab+ and the colors it brings.

I've been experimenting a bit with BRS recommended tweaks to the AB plus setting for optimal viewing and coloration. Basically it just increases focus intensity of red, green and white from 24% to 33%. So far I've seen even a little more coloration and growth along with nice viewing.

 

[BeanAnimal]

For the vast majority of fixtures used in the recommended number for a given footprint -- most people will see enhanced growth at all channels at 100% output with few side effects as long as common sense is used.

For aesthetics, one can start tuning down the reds, whites ad greens to a pleasing look, with little effect on overall growth.

Many of the better fixtures are designed to have a pleasing output at all channels 100% to begin with.

Where people get into trouble is running fixtures at some partial overall output and then turning down important channels even further. But this is not something generally that a PAR meter will tell you due to its inability to differentiate important wavelengths from those that are not.

 

[reef’r]

https://www.reef2reef.com/threads/par-map-t5-led-hybrid.1108464/ Link to my par findings