In preparation for tonights meeting, I took some PAR readings on my tank. Results are:
Blueline 120 watt LED pendant:
White LED's only
Out of water - 600
1" under water - 300
5" under water - 200
10" under water - 120
White + Blue LED
Out of water - 800
1" under water - 480
5" under water - 330
10" under water - 185
The LED's are over the high part of my rock work. Can't take a measurement in the sand.
TEK Light 4 bulb T5 fixture:
White bulbs only (Giessemann Midday and AquaBlue+ bulbs)
Out of water - 400
1" under water - 195
5" under water - 145
10" under water - 100
Sand bed (22") - 67
White and Blue bulbs together (Actinic + and Pure Actinic + white bulbs)
Out of water - 410
1" under water - 275
5" under water - 187
10" under water - 125
Sand Bed (22") - 100
All lighting together - LED's and T5's:
Out of water - 600
1" under water - 420
5" under water - 335
10" under water - 245
Sand bed (22") - 138
My conclusions are this LED has higher initial PAR but loses intensity faster when going deeper in the water. T5 has lower inital PAR but loses intensity less when going deeper in water.
Here's another thing - the type of LED makes all the difference. Lisa's tank has Mazarra LED's. Here are her readings:
At 100% intensity:
Out of water - 1400
1" under water - 850
5" under water - 650
10" under water - 400
Sand bed (22") - 190
Much higher readings, but as you move the PAR meter left and right in the light field, the numbers jump all over the place. Directly under the LED there is great PAR, but move 3" to the left or right at the same water depth and the PAR gets cut by more than half.
Lisa's anemone tank has Current USA's TruLumen LED strips over it. The PAR out of water is 200, 1" under the water - 80, 5" under the water - 45. But the Par is relatively the same when you move the meter to the left and right due to the diodes being in a row instead of focused in a small footprint.