Light Measurement vs Water Death

[Wes888]

Did quite a bit light measurement in the tank today. Got a little sun burn on my hands, and unforturnately the sacrifice of a fairy royal basslet. :sad: In order to get the accurate measurement, all the pumps and powerheads were off. All of the powerhead except the K5s were already fish proof. The front of K5 already has a grid that "most" fish can't get though...

We only got this basslet few days ago and didn't even have a name yet. I like to dedicated these measurement to him. :bye2:

 

[Ted]

Sorry to hear of your loss.

 

[Wes888]

A little off center in the tank

The light was measured a little off center between the two HQI:

 

[Wes888]

This measurement was about 2" away from the glass, and my tank is only 16" deep. Interestingly, the light measured was almost just half of what's in the middle of the tank (as seen in the last graph). So if you have your rock work leaning on the back glass all the way to the top, the light would be the same as in the mid tank in the mid height.

 

[Wes888]

This part was the main reason I did the light measurement. In order to fit the 120mm computer case fans, I had to lift the light 4.75" off the top of the tank rim. This measurement was to set the light meter at a fixed location in the tank and just adjustment the hanging height of the light fixture. The optimal height seems to be 3.5-4" above the tank. Just ordered a few 80mm fans to replace my 120mm fans now.

 

[Ted]

wow nice research thanks for the info:Cheers:

 

[Wes888]

Thanks.

Now I'm afraid to get another basslet...

 

[ccCapt]

Nice job on the charts. Unfortunately, LUX isn't of much use in a reef aquarium. If you can get ahold of an Apogee Quantum light meter and get some reading in PPFD (Photosynthetic Photon Flux Density), the #'s would have more meaning.

https://www.livingreefs.com/par-meter-readings-t19189.html

 

[Wes888]

Thank you. But I'm not looking for the effect of different type of light or different spectrum of light though. The purpose of my measurement was to find the correlation between the light intensity compare to water depth. More importantly, how high the light fixture hanging affect the intensity of the light.

I entered the numbers you did with the PAR meter and plot the charts. The results have very similar pattern like I had.

This chart was using your numbers ( I changed the X-Axis limit to just 7" to 21" for easy compare to my numbers):

This is from mine:

Again, the purpose was not to compare different light. The Arcalic line in there has no particular reason.