Estimating PAR from wattage

[Shnetts]

After seeing BRS and serious reefs saying they can accurately estimate par from the wattage being used. What formula are they using to calculate this? and has anyone else been able to at least somewhat estimate there par?

 

[VintageReefer]

After seeing BRS and serious reefs saying they can accurately estimate par from the wattage being used. What formula are they using to calculate this? and has anyone else been able to at least somewhat estimate there par?

I haven’t seen these videos but par is variable based on distance/water depth, spectrum, focal lenses.

Example I have a led bar with focused lenses, and 2 channels. One channel is all blue. The other channel is whites/violet. Channel A at 100% is about 200-250 more par than channel B at 100%. Both channels are same number of leds and watts.

 

[BryanM]

Yeah, I'm not buying in to this either as there are quite a few variables at play as Vintage noted. Maybe some ideal scenario, but in the real world I just don't think this passes the sniff test.

If you want to know your par, you either need to have a par meter, or the exact same setup someone else has, who has a par meter.

 

[rtparty]

If you know the light and how it’s designed, you can get a pretty good idea and I bet Ryan shows his thought process at a later date

 

[VintageReefer]

If you know the light and how it’s designed, you can get a pretty good idea and I bet Ryan shows his thought process at a later date

Maybe they are talking about a very specific example like a xr15 vs a xr30 where both units are similar but one has more diodes / watts?

I can’t see a real way to estimate between completely different fixtures

 

[Shnetts]

If you know the light and how it’s designed, you can get a pretty good idea and I bet Ryan shows his thought process at a later date

Yeah I have just gone off what the manufacture says par is at different distances and intensity to estimate what im getting in my tank.

 

[Shnetts]

At first I thought it was just for older t5 type lights, but he said he was able to estimate a newer light within 2 PAR of the meter, also said he has 6 more new lights coming in to attemp to estimate on.

Curious how that plays out and if some sort of formula could be developed to at least get a estimate, even if its a 50 degrees off actual

 

[rtparty]

Maybe they are talking about a very specific example like a xr15 vs a xr30 where both units are similar but one has more diodes / watts?

I can’t see a real way to estimate between completely different fixtures

I think you’d be surprised. Each fixture has a certain design whether it’s reflectors, optics, nothing. The wattage the LEDs use is also known. You can look at the ratio of LEDs used and get a good idea of PAR for each.

Time will tell but it’s not nearly as difficult as some think

 

[BeanAnimal]

After seeing BRS and serious reefs saying they can accurately estimate par from the wattage being used. What formula are they using to calculate this? and has anyone else been able to at least somewhat estimate there par?

The formula is called BS = lm/w * count.

First, “PAR” isn’t a number—it’s a concept, typically expressed as PPFD (Photosynthetic Photon Flux Density). It’s a rough measure of photon energy in the 400–700nm range that photosynthetic organisms can use—not necessarily do use.

“PAR” spans a broad spectrum, and much of it is irrelevant or even useless to coral. So even if your PAR measurement were perfect (which it never is -- even close), it still wouldn’t tell you what you actually need to know.

Now try estimating that from watts—ignoring spectrum, lensing, emitter efficiency, diode types, fixture design, and user settings—and the whole thing becomes laughably meaningless. I don't mean "kind of meaningless" I mean absolutely and utterly useless.

 

[BeanAnimal]

At first I thought it was just for older t5 type lights, but he said he was able to estimate a newer light within 2 PAR of the meter

Whoever "he" is -- has no clue what "he" is talking about. "He" is full of more crap than a goose farm. Full Stop.

 

[Shnetts]

becomes laughably meaningless.

what exactly becomes meaningless? The number that we are using to measure PAR?

Obviously PAR is not as simple as many think but measuring a number is still important in keeping coral.

 

[rtparty]

Well, this thread could have been decent with good conversation but someone left the bean dip out overnight and it turned rancid

 

[Shnetts]

Well, this thread could have been decent with good conversation but someone left the bean dip out overnight and it turned rancid

My goal was to see others inputs on estimating par, I didn't think it was a touchy subject.

For new people having a comprehendible way to understand their lights and estimate would be a good thing.

 

[rtparty]

My goal was to see others inputs on estimating par, I didn't think it was a touchy subject.

For new people having a comprehendible way to understand their lights and estimate would be a good thing.

I think it’s a great topic!

Helping people be more successful and making it easier is always a good thing IMO.

 

[BeanAnimal]

what exactly becomes meaningless? The number that we are using to measure PAR?

I think my post speaks for itself. What part (honestly) are you not clear on? I will be more than happy to elaborate.

Obviously PAR is not as simple as many think but measuring a number is still important in keeping coral.

IMHO and given fact (not reefing lore or common practice) measuring "PAR" is not an "important" part of keeping coral. There have been countless thousands (tens, hundreds, millions) of successful reef tanks that have never seen a "PAR" meter. The tool and its output are almost universally misunderstood by the vast majority of those in this hobby that think they are using it to some meaningful end.

The irony is that PAR tells you nothing about spectral quality, distribution across the tank, or how a given coral actually uses the light it's exposed to. It’s like measuring all calories as equal -- technically a number, but practically meaningless if you don’t know whether it’s from sugar, protein, or alcohol. -- the fat, carbs, or protein -- let alone the subsets of those and their ramifications on every aspect of health and bioavailability.

Well, this thread could have been decent with good conversation but someone left the bean dip out overnight and it turned rancid

Sometimes nonsense is best stopped in it's tracks. Ignoring the conversation about the actual usefulness of PAR measurements or their accuracy themselves. Let's just say "PAR" Is the most important thing in the world, for the sake of argument...

There is just no (even remotely) reasonable way to even come close to estimating par by looking at the wattage of a fixture.

Sure - one could could:

1 - Count the emitters.
2 - Look up the BRAND and TYPE and BIN of each one, recording its maximum luminous efficacy.
3 - Do the math, based on the datahsheet wavelength(s) of each emitter, to find its maximum Flux at 100% output.
4 - Assume that all emitters are running at 100% output with no thermal throttling (they don't run this way)
5 - multiply by some driver and power supply efficiency
6 - multiply by some arbitrary lens coefficient at some arbitrary distance

And get an extremely rough estimation of "PAR" (PPFD) at 100% output in a perfect world. And even that number will be:

1 - insanely ballpark (wildly off) due to the number of variables.
2 - derived by an exercise that takes a tremendous amount of work and math.

So there is NO WAY that "he" or anybody is going to come close to a "PAR" estimate by looking at a mixed emitter LED fixture. The notion is patently ridiculous and anybody who puts forth otherwise has absolutely no clue what they are talking about. There is no conversation to be had, it is a non starter.

The bean dip is not sour... bean dip is never good.

 

[Shnetts]

There have been countless thousands (tens, hundreds, millions) of successful reef tanks that have never seen a "PAR" meter.

Your right not many people have a par meter, but I can guarantee you every single one is trying to estimate to some extent how much their lights are outputting......

Your making it sounds light par is some sort of imaginary thing we all came together to make up?

Different corals need different amounts of light.....PAR seems to be the easiest way to measure this? If i put an acro at the bottom of my tank in the shade its going to die....if i put an acan on the top of a rock being blasted its going to die.

 

[rtparty]

The bean dip is not sour... bean dip is never good.

The most sense in your whole ramble

 

[strich]

dang we got Butter Bean in here swinging for the fences.

I think you probably could come up with napkin math PAR estimates based off of wattage, light spread, depth and color mix pretty easily. Dunno about bring within 2 PAR but I think ballpark is possible.

Now, how useful that would actually be to a reefer I dunno - PAR is just one small part of a complex set of variables that determine coral health and so is a loose PAR number guess really helping or hindering the troubleshooting process?

 

[FUNGI]

I think this comes from the plant growth world, as they have tons of on-line calculators for this....how much PAR will I get using x amount watts and x bulb type....
I dont think its too relevant in the aquarium world as too many variables....but maybe as a guideline use..?

 

[Reefering1]

Your right not many people have a par meter, but I can guarantee you every single one is trying to estimate to some extent how much their lights are outputting......

Well, not every single person.. quantifing your lighting can also be achieved by having appropriate lights, understanding where the cone of light falls and how it is effected by the other cones of light, can be more practical than having a arbitrary number. I have 3 zones of lighting. High(directly under/ between fixtures), medium( off center of fixtures), low(outskirts of tank. I have no need to know more than that...