Par question

[sadie]

 

I was looing to see the lighting requirements of my daily polyp.  I am thinking of gluing it to one of my islands and putting it a high in my tank.  I just wanted to make sure there wasn't too much light for it.  I remembered someone posted the par lighting map for my 16 gal BioCube, but couldn't remember where.

 

I found this chart, but it says at the top, I only have 50-60 Par.

9-cl15661-ledbiocube16-par.jpg (600×469) (coralifeproducts.com)

  Here is a quote for the daisy polyp care-

"Daisy Polyps require a low to moderate lighting level,(PAR 100-250)"

 

They are considering 100-250 Par low to moderate and at my HIGHEST I only have 50-60.  Am I reading something wrong, or something?  I feel a bit confused.

 

could someone explain this a bit more?  

 

 

[A.m.P]

Cloves don't need that much par, and the par rating of the biocubes varies based on the light in the hood (there are different versions).

I really advise looking at Tidal Garden's Par reccomendations, they're more helpful and realistic for most use cases and reef hobbyists.

[mcarroll]

If you aren't measuring the PAR in your tank, you can let go of that whole line of thinking....you don't necessarily know anything about your tank from looking at links like that about someone else's tank.  

 

If you want a measurement but don't have a PAR meter, then use a lux meter.  A decent handheld lux meter is very inexpensive ($7+), and while you wait for that to ship you can use a free lux meter app for your smartphone.  Apps, as I'm sure you know, can be hinky though....so test the app before you use it on the tank to make sure it really works.

 

Let us know if you get any readings from your tank!  👍

 

 

[sadie]

11 hours ago, mcarroll said:

.you don't necessarily know anything about your tank from looking at links like that about someone else's tank.

the link isn't too someone else's tank, it's from the maker of the tank.  It shows the par for a 16 gal BioCube, which is what I have.

 

11 hours ago, mcarroll said:

and while you wait for that to ship you can use a free lux meter app for your smartphone.

I don't have a smartphone, and don't want one.  I'm not much into phones.  Pluss we're a dead zone, so they won't come in here.

 

If I order something, I want the better of the two.  So which would be better a par meter or a lux meter?

[A.m.P]

For half the price of a PAR meter just buy an AI prime and dremel a hole through your biocube lid to mount it in.

[mcarroll]

On 1/9/2021 at 5:44 PM, sadie said:

They are considering 100-250 Par low to moderate and at my HIGHEST I only have 50-60.  Am I reading something wrong, or something?

I think you were reading too much into the PAR chart you linked.  This is a good thing!

 

On 1/15/2021 at 3:27 PM, sadie said:

the link isn't too someone else's tank, it's from the maker of the tank.  It shows the par for a 16 gal BioCube, which is what I have.

Sorry I didn't look closer at first.  Most importantly it also says that those numbers were taken 12" from the center of the fixture....it's a point of reference, and more info than many manufacturers will give you, but not much good for the comparisons we'd like to make.

Plus, like @A.m.Psaid, it's possible that doesn't even apply to the model of BioCube you have.  (Although it might.)

 

It's more accurate to say that your tank has more than 60 PAR in the top 12"...and less light under that level.  It doesn't give us any more than that.

 

Having your own measurements is the way to go.  👍

 

On 1/15/2021 at 3:27 PM, sadie said:

If I order something, I want the better of the two.  So which would be better a par meter or a lux meter?

Either will do the job....but the lux meter is a fraction of the cost.  If you think you have other uses for the PAR meter, then it could be worthwhile.  

 

But literally it's spending $7-$15 vs spending $200-$500.

 

 

[sadie]

Lux meter ordered

[mcarroll]

Sorry I'm still slow on the uptake here....just noticed that you have the BioCube 16.

 

Measuring at 12" is almost at your sand bed....perfectly fine number for the sand bed IMO.  (Unless you're trying to grow a clam there!)

 

So that number is almost the opposite of what you thought it was.....it's your minimum level, not the max.

[geekreef_05]

On 1/9/2021 at 5:44 PM, sadie said:

"Daisy Polyps require a low to moderate lighting level,(PAR 100-250)"

 

 

This statement is totally incorrect. Not sure where you got it. Low to Mod light is 50-125 range. 250 PAR is like the bottom level for SPS. 

Your polyps will do totally fine anywhere in that BioCube. Almost all soft corals will like that range of lighting. 

 

hope that helps. 

[nanoreeFan]

Do you divide the Lux by 60 or 30 to get the par number? And at what LUX setting on the  meter do you use ? The 20,000 LUX range or 200,000? Thanks

[geekreef_05]

You cannot convert Lux to Par, they are two different things. Lux is relative to the human eye and PAR is relative to photosynthesis, which is relevant to reef tanks. 

Just totally forget everything you're trying to learn about Lux and learn about PAR instead. 🙂

 

[nanoreeFan]

Yet there are plenty of threads of folks converting their Lux meter reading against an actual par meter with great results. Yes.... its not a real par number of course. 👍 Sadie, did you have any luck with one?

[mcarroll]

23 hours ago, nanoreeFan said:

Do you divide the Lux by 60 or 30 to get the par number? And at what LUX setting on the  meter do you use ? The 20,000 LUX range or 200,000? Thanks

For sunlight the conversion factor is 50....I use that and it's close enough.  (I also use it because the math is easy. LOL)

 

Use the lowest setting that doesn't error out on the light source you're sampling.

 

23 hours ago, geekreef_05 said:

Just totally forget everything you're trying to learn about Lux and learn about PAR instead. 🙂

What would make you say that???

 

I would suggest checking out Dana Riddle's Advanced Aquarist articles (now on reefs.com) that mention lux or lux meters and how to create a conversion factor – it's simple!   

 

Even Apogees website has some pre-calcualted lux:PAR conversions if you don't want to do that.

 

And Google just helped me bump into an Osram-Sylvania doc (An FAQ question with it's own PDF....wow!) that explains how as well....never saw this before:

https://s3-us-west-2.amazonaws.com/oww-files-public/e/e8/Conversion_lux.pdf

 

[jservedio]

On 2/2/2021 at 11:32 AM, nanoreeFan said:

Yet there are plenty of threads of folks converting their Lux meter reading against an actual par meter with great results. Yes.... its not a real par number of course. 👍 Sadie, did you have any luck with one?

So in theory, LUX can be converted to PAR, but the conversion factor is going to be different for literally every single light setup, so be extremely careful when attempting to convert the two because you can be off by a factor of 2-3 extremely easily and even more if you run heavy UV since UV contributes virtually nothing to LUX while contributing a massive amount of PAR. Using the "Divide by 50" is a really poor choice if you are using LEDs that are heavy in RB/UV like most of us do because your spectrum is not even remotely close to sunlight. For example, my conversion factor on my new tank at peak intensity is dividing by 16.

 

To see why LUX and PAR don't correlate in a neat and tidy fashion and why the spectrum that your lights are running at play a huge role in determining the conversion factor, just look at the following graphs.

 

Here is LUX curve - you can see that 400nm UV and 460nm RB provide virtually no LUX while 550nm provides the most LUX:

 

 

Here is a graph of Photosynthetic Absorption by Wavelength: You can see that both 400nm UV and 460nm RB provide a TON of PAR while 550nm provides virtually nothing - it's basically the inverse of LUX:

 

 

Now, you can certainly figure out the conversion factor between LUX and PAR for a given light at a given spectrum, but you can see from a graph of the sunlight's spectrum that is looks absolutely nothing like the spectrum graph of a typical LED reef light.

 

 

For example, with my Radions on my new tank at peak intensity I am making almost exactly 200 PAR on my sandbed with a LUX of 3400 (24" directly below light). If I lower my UV/RB down and crank up the green and white a bit for a spectrum that looks closer to 12,000K while using exactly the same amount of power (~62w), my PAR decreases to a bit under 100 on the sandbed yet the LUX goes all the way up to 5600. So for my normal, peak day spectrum my "conversion factor" for the sandbed is 16. For a more "natural" looking 12,000K, the conversion factor is roughly 60.

 

If I used the "divide by 50" on my own tank and used LUX to try and get 200 PAR to the sand, I would be totally screwed and would fry literally every single coral in the tank. I would believe my corals were getting only 68 PAR on the sandbed and look to increase the power since I've got some acros down there. However, this would be a massive mistake since they are actually getting nearly four times that much PAR!

 

If you want to know PAR numbers, rent a PAR meter. Otherwise, start low and slowly increase. Let your corals tell you when they have enough light!!!

[sadie]

I have not received my lux meter yet.  I don't remember where I ordered it from so I can't call.  I'm starting to think I DIDN'T order it and just thought I did.  

 

I'm beginning to think my lights might be defective.  My RFA are SLOWLY getting smaller.  Some of my coral are holding their own, but still no growth in anything- even my GSP.

 

I thought my lights were kinda flickering, but then thought it was the movement of the water, but no- they are def flickering.  When I lift the hood and look at the lights, they flicker.  I'm thinking this is not a good thing. 

 

I will call the company and also order a flux meter for real this time. 😁