what device is used to measure par?

[reef_keeper]

also what exactly does PAR stand for and how does it effect the reef?

[Sugar Magnolia]

A PAR meter. If you belong to a local reef club, most have a PAR meter that is shared with the members as they are quite expensive.

From Anthony Calfo:

As aquarists, we often struggle with light issues:

- when to change old lamps and how many of a multiple to change at one time

- will the new coral I'm buying suffer light shock in my tank and how can I avoid that

- is my new or current light canopy in the optimal position and are my lamsp close enough, too far or too close to the water

- does this window or greenhouse glazing offer enough or too much sunlight?

- does the light I'm using have not only enough intensity, but enough PAR(!) to keep my reef corals and creatures alive

There are many more challenges we encounter that could readily be addressed with the use of a PAR meter. A keyword search of the Internet will reveal other authors such as Sanjay Joshi and Dana Riddle of Riddle laboratories with published articles on this issue. I like and recommend a PAR meter for all non-casual aquarists. Most of us have many thousands of dollars invested in our reef systems. A couple hundred dollar investment in a light meter can make a huge difference in the success and health of the aquarium. Several members of this board own the brand below and like it well. I agree FWIW:

http://www.apogee-inst.com/bqm_spec.htm

Re: which to choose, you must ask yourself:

are you measuring electric lamps, sunlight or both?

Do you want a water proof sensor or not?

My advice is to get all of the above if you can afford it my friend: Model QMSW-SS

(and to be clear - I do not know these people or this company, I have never taken a free product sample or any sort of comp from them... and MD does not sell these units presently (nor have plans). It's simply a good brand/product that stands on its' own merit. Hence my recommendation.)

.

Anthony Calfo