10-03-2013, 05:49 PM
Join Date: Jul 2010
Location: Dallas, Texas
| | Re: PAR data collection
Zapins, that is what we are all trying to figure out! Here's my subjective opinion, and I am inviting scorn from all corners with this. But I can take it, LOL! All numbers refer to PAR at substrate.
20 umols is low, below this only the most shade tolerant plants will grow well. 40 umols is medium--a very large variety of plants will grow well. 80 umols is high and will grow almost anything. Much above 80 umols at the substrate you are driving the Ferrari on an icy mountain road, and had better know what you are doing.
Something I think is important is photoperiod, and how long the light is at what intensity. Again, my subjective opinion is that the "midday burst" schedule most closely resembles nature, and you may be able to flirt with high PAR using that method. This comes partly from my observations of sunlight in my own ponds. Except at midday, surface reflection greatly reduces the amount of light received by submerged plants.
BriDroid, our meter has both electric light and sunlight settings. The outdoor readings were taken with the meter in sunlight mode. However, the manual says that if you use the wrong setting the error is only 5-10%, I can't remember up or down. You can get that much change just by moving the sensor a fraction of an inch in a planted tank, so I regard it as insignificant.