75 Shallow Finally PAR Mapped


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Mar 30, 2019
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Gulf Breeze
So, I finally rented a PAR meter and mapped out my 75 shallow. The tank is 60"X18"DX16"H. My lighting consist of an Amazon, 4 bank T5 fixture and 2X48" OR3 blue+ LED bars. All lights are enclosed in a hood. The lights are approximately 8.5 inches off the waters surface. I have a map for the OR3s alone and two maps for OR3s plus two different T5 combos. The first is my original combo, OR3s plus 2Blue+ 1Coral+ and 1actinic, all ATI lamps. This combo was 1 year old at the time of measurement. The last mapping photo is the 2XOR3s plus with the new T5 combo, 3B+ 1C+ all ATI. You will see, that while the OR3s do not provide a lot of punch deeper in the tank (probably be reduced due to the angle) they definitely provide the blue LED pop! On the second map I quickly found out that 48 inch fixtures in a 5' tank drop off dramatically on the ends at the 8 inch height. Obviously the middle of the tank is receiving the most punch. Back in the day I ran MH with VHO actinics and was always a fan of the actinic bulbs, however; in this configuration it seemed to reduce PAR and be a waist of a lamp when compared to the blue+. I swapped out all of the bulbs to the new config, 2XOR3s plus the new T5 combo, 3B+ 1C+ all ATI and was surprised at the increase. On the third map I left the old measurement in a from-to type format so you can clearly see the increase. The PAR clearly still drops off dramatically on the ends with the center of the tank receiving the highest PAR.

2X OR3s 48.jpg T5_ 1yr_ 2B+ 1C+ 1Actinic and OR3s.jpg T5 New 3B+ 1C+ and 2 OR3s.jpg

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