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PAR Meter

3891 Views 6 Replies 4 Participants Last post by  bibbels
I started playing with a par meter and although the results have been enlightening, pardon the pun, I don't know exactly what they mean. Does anyone know of chart, graph, etc. showing what par readings mean? What are good par readings?
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I don't have any graphs or charts, but I can give some loose ranges.

The following are average readings at substrate level. Readings at higher levels in the tank can be much higher depending on light height, number of bulbs, reflector quality, etc.

Minimum level for most plants is around 25-30 micromoles
Low light around 30-40
Moderate light 40-80
High light 80-150
Very high light >150
Some may have readings to 600 and above
Full sun ~2000 micromoles

Best results are probably achieved with readings that are pretty uniform from bottom to top (like 40 at substrate and 80 near top)

BTW, please share your results and specs.

My 125 gallon has 4 x 39 watt Tek II T5HO retrofits mounted to the top inner surface of my 10 in. tall wood canopy. Bulbs are roughly 30 inches above substrate. My PAR is 40-70 at substrate. About 150 just under the water surface. I have my PAR sensor mounted on a Closetmaid shelf bracket :D (see link below for what I mean) and just move it around the substrate trying to keep the sensor as level as possible.

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What brand PAR meter do you have anf where did you get it from? I'm looking to get one.
I have an Apogee QMSS-E. I bought it through their site during a group buy sponsored by Reefcast a few months back.
bibbels post is very good.

benjavan, the problem is that the use of PAR measurements in FW has really only started to catch on the last few years, so a lot of the numbers out there aren't exactly set in stone.

I agree with bibbels, be sure to post your results, only helps to expand everybody's knowledge.

I, too, purchased one from Apogee during the Reefcast group buy.
The meter that I was using was an Apoggee with a separate sensor. I am just starting to figure the results but so far it looks like the HO T-5 lights are great. I have four of them on a 90and get a reading of 82 at the bottom. I compared a 39w HO T5 to 2 30w normal output T8s. The T5 gave a reading of 54 at 11 inches of depth. The 2 T8s were only 32.

Thanks for the input bibbels, were did you get the info?
Thanks for the input bibbels, were did you get the info?
A compilation of info, most from The Barr Report.
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