PAR Meter Rental

[Sartium]

Hey R2R gang I apologize for posting this twice but the first post was in the Michigan forum and there doesn't seem to be any activity in that forum. My question is does anyone know of a club or company in Metro Detroit that rents PAR meters?

 

[mcarroll]

Just in case you come up dry...

I really recommend getting a lux meter instead.

The cost is anywhere from $free to around $15. For the most common purposes it will do just as well for you as a part meter would.

I would start with a free app for your smart phone. "Galactica Luxmeter" is one for the iPhone which people seem to have good luck with, but there are several for iPhone as well as Android.

Make sure the app is set to use the correct camera on your phone.

Double check your results with someone the first time you use it to make sure the app is controlling the camera properly.

A $15 handheld [HASHTAG]#lux[/HASHTAG] [HASHTAG]#meter[/HASHTAG] is a smart buy, but you have to wait for shipping.

For reference:

• 100,000 lux = 2000 par = "Direct sun" at sea level
• 20,000-80,000 lux seems to be the safe range
• 20,000-40,000 lux seems to be the ideal starting range
• All measured at the water surface

 

[Sartium]

@mcarroll thanks for the information, exactly how do you use the iPhone app in your tank? Do you point the camera at the rock or sand surface from outside the tank?

This sounds like a great starting option!

 

[mcarroll]

You hold it at the water surface pointed up at your lights.

 

[Sartium]

Ahh I see, that's not giving me a good indication of the light at the bottom of the tank though.

 

[saltyfilmfolks]

The tank is probably not that deep so the fall off is minimal.
Try the app first. Put it next to any light source. Move the meter away from the source the same distance as the depth of the tank.
Depending on your tank and light situation you can do the same with the tank light.
@mcarroll Im slowly working on the glactia app. it has two modes direct(at the light) and reflected(from the sublect). If you point the meter at a white patch on the sand bed there seems a very close (reliable)correlation in the readings.
The color of course will affect the reading(brown less reflection, bright white more), but the exact same can and must be said of the par meter as it is using direct & reflected light plus color, direct and reflected.
Look up tanks that have had the par charted and youll see this correlation.
Heres melev's.
http://melevsreef.com/node/678
Its also why a black background is the worst thing you can do for your par.
But it does look good.

Again the $15 meter is better than the app. the $15 meter is almost as good as my $500 meter.

 

[Sartium]

I am going to try this first for sure guys thanks for all the help!

 

[mcarroll]

It does give you a reasonable idea what's going on under the water.

Our corals are much more adaptable than they sometimes get credit for. Knowing lighting values in exact locations of your tank is part folly and part unnecessary, IMO.

Folly
If you watch how the meter fluxes with the slightest movement even above water...now imagine below water where the environment is several orders of magnitude more in flux. Even sticking a sensor in a particular location on your rocks can only give a flawed account of the actual conditions. A number you pick to record for that location necessarily has to be some limited account of what you actually observed on the meter like an average or peak value.

Necessity
In general, stony corals are able to survive in light from "direct sun" intensity all the way down to 1% of that in the wild. That's from about 100,000 lux down to about 1,000 lux.

They reach their compensation point (able to grow) between there and around 5,000 lux, depending on the coral.

I have one SPS tank growing under about 10,000-15,000 lux. Another on the same system and mostly the same corals at 40,000 to 50,000 lux. The corals seem equally happy in both.

 

[mcarroll]

@mcarroll Im slowly working on the glactia app. it has two modes direct(at the light) and reflected(from the sublect). If you point the meter at a white patch on the sand bed there seems a very close (reliable)correlation in the readings

I haven't messed with the mode that uses the camera on the back, I assumed it was doing the same thing as the front camera just in the other direction. Interesting.

 

[mcarroll]

I thought once upon a time I heard a rule of thumb that light attenuates by half for every doubling of distance through air and to one quarter for every doubling of the distance through water....something like that. Can't remember for sure and haven't seen it repeated again tho...

Would be interesting to see if the reflected light measurement corresponds with the computed value.

 

[saltyfilmfolks]

I haven't messed with the mode that uses the camera on the back, I assumed it was doing the same thing as the front camera just in the other direction. Interesting.

easy test with a white paper on the desk. should be very very close. simple test Desklamp over white paper. incident meter on paper, phone reflected meter reading white paper close to sensor.
(should be an 18% grey card but...)
probably very close. wont recommend it for newbs yet.

I was packing my other meters and picked up my 1degree spot meter to check batteries and calibration date and the lightbulb went off.
its something is actually do every day. Indecent light meter & spot meter. duh. photography 101.

 

[saltyfilmfolks]

For The OP, do BTW try to get a par reading. Its quite eye opening.