How does white light intensity percentage effect par?

[camilenoel]

I have a 14g nano that I want to be LPS and Softy dominant with a few SPS up top. The light I have is the Smatfarm G3 60w. Smatfarm provided a par chart for this light (attached below) but my question is, how the intensity percentage affects the par reading. For example, my light is mounted at a similar height from the tank and the par readings at depth that they provide are higher than I want, so I turned down the intensity. But now without spending a bunch of money renting a par meter is there a way I can approximately calculate what the par readings would be at certain percentages?

I also attached a photo of my nano. Light is mounted 9in above the water surface and sand bed is 14in below the surface. I currently have the blue channels at 100% and the white at 40%.

If anyone has any recommendations please let me know! I only have one fish in there and plan on adding corals in a couple of months! Thanks!

 

[MoshJosh]

It depends on a few factors, but I think the relationship between light intensity (percentage adjustment on the light) and PAR will be a linear one. So if you are running the light at 50% you will likely be getting 50% of the reported PAR.

Keep in mind manufacturers generally report PAR levels of the light at 100% intensity on all channels, so depending on how many LED are in each channel will affect how much of the overall PAR they are responsible for. For example Fluval Marine lights have a higher concentration of white LED so turning down the whites will have a disproportionately large effect on PAR than other channels.

 

[oreo54]

I have a 14g nano that I want to be LPS and Softy dominant with a few SPS up top. The light I have is the Smatfarm G3 60w. Smatfarm provided a par chart for this light (attached below) but my question is, how the intensity percentage affects the par reading. For example, my light is mounted at a similar height from the tank and the par readings at depth that they provide are higher than I want, so I turned down the intensity. But now without spending a bunch of money renting a par meter is there a way I can approximately calculate what the par readings would be at certain percentages?

I also attached a photo of my nano. Light is mounted 9in above the water surface and sand bed is 14in below the surface. I currently have the blue channels at 100% and the white at 40%.

If anyone has any recommendations please let me know! I only have one fish in there and plan on adding corals in a couple of months! Thanks!

You have 3 channels and as stated above you do not know the proportions of par from each channel

A: Main Channel: 14000K Cool White,blue,warm white
B: Blue Plus: 450nm Deep Sea blue+460nm Dark Blue+470nm sky blue
Curple Plus: 410nm Violet, 420nm Purple 430nm Indigo blueBlue(470nm)

Sure if the output is equal it would be easy
Say 33% from each.
Can't go by the number of each either since current and efficiency could be different.
Like violet LEDs generally have lower photons/watt numbers than say royal blue.

Since whites are blue plus phosphors and manufacturers like all "parts" from one supplier there is a chance that 1) blues and whites have approximately the same efficiency. 2) They are driven by the same current you may be able to at least estimate that ratio.
Like if 150 par is from blue and white and you have 10 " blue" and 5 white LEDs.
100 par is from blue and 50 from white
Cutting the white channel to 50% cuts par by 25.
Total is now 125.
The reverse blue 50, white 100 would be 100 obviously.

Then there is violet..

Anyways overall point is it's difficult without more info.

Btw NOT a good idea to try to count the LED colors by eyeball......

 

[jda]

Do not trust anything from a manufacturer. See if there is a local hobbyist or club that lets you borrow a PAR meter - ours in Denver has a few to loan and I will loan mine out too. Pitt is a big enough city that you should be able to find something.

 

[camilenoel]

Do not trust anything from a manufacturer. See if there is a local hobbyist or club that lets you borrow a PAR meter - ours in Denver has a few to loan and I will loan mine out too. Pitt is a big enough city that you should be able to find something.

Thanks. This was my first plan but unfortunately I haven’t found anyone yet and I don’t really want to spend $100 to rent one for BRS. I’ll keep looking!

 

[jda]

3RMAS still around?

 

[bishoptf]

Thanks. This was my first plan but unfortunately I haven’t found anyone yet and I don’t really want to spend $100 to rent one for BRS. I’ll keep looking!

Eh you can buy one thats almost as good as the apogee ones for under $200, I think they are around $180.

Here is a write up from @telegraham that goes into more detail, looks pretty close to me...https://humble.fish/community/index.php?threads/need-a-par-meter.17795/

 

[camilenoel]

3RMAS still around?

Yes! I dont know why I didn’t think to ask in that group!