I just recently used a Par Meter and this is the informationthat I have learned about my tank. I hope this information can be helpful. First of all understanding the equipment: The Photosynthetically Active Radiation (PAR) meter measuresthe amount of light, which can be used to determine the intensity inside yourtank for growing corals. My tank: Description: 95 g corner reef tank with 400-watt MetalHalide Lamp. Dimensions: 34 ½ sides giving a 4ft panoramic front view.From the top of the tank to the substrate is 21 inches. From the Lamp to thetop of the tank is 8 ½ inches. Results: On top of the water not submerged: 1800 Two inches below water surface: 1100 Half way down: 375 Bottom of tank: 250 The above measurements were taking in a straight line underthe lamp. The further from the middle of the tank the intensity drops. My lowest reading was 120. Importance: I have certain hot spots in my tank where the lamp has moreintensity. I quickly understood that mushrooms do not like 475 but ratheraround 250. My poor mushrooms almost died. In the same since, I had star polyps in an area that wasaround 350 they were ok, but I decided to move them to a more tropical environmentof about 425. Within a week they doubled in length. Lessons learned: I have learned that animals can be alcimated to the light.Placing animals depends in part by their previous conditions. Animals have favorable conditions that theylike best. I hope this can help newer salt water owners like me. James
