Perhaps the numbers are too blurry so Ill explain. The 360 is the light at the end of the tank just below the water surface. The 120 is what I got when I added my black needlepointer's mesh. Those looking for acclimation... the needlepointer's mesh cut the output by 2/3... not bad.
The light at the center of the tank, just below the waterline was 550. This was about the highest output I could get just under the water (no glass).
The part that interested me was the 475 and 450. I can see that I fudged the numbers already... they should be reverse. Just below the water, I was able to get 475 without a glass cover. Then I slid the 1/4" starphire glass over the sensor, and I got 450. Not bad... I lost a minimal amount of light... pretty good considering all of the waterspots, water, and dust on the glass... not to mention... its still 1/4" glass.
Now some may ask... how do you get such varying results across the surface of the tank? Well... in the above tests, it was because IN each test, even though the sensor and lights were in the same place, from test to test, the sensor would get moved from front to back... and the relative amount of light varies a bunch because the sensor is so close to the bulbs... if Im under the actinic03, the output will be lower than under the blue+.
So anyways, heres the important thing to note... a peak of 550, and my 1/4" starphire only robbed me of about 5% of my output. So I would imagine a 1/8" acrylic sheild, if properly vented behind, would rob me of what... 2% maybe?
So I took a Tek sheild... notched one end of it so I could then bend a 3" flap down at the end where the fan sits. This flap directs the air up and across the bulbs... between the reflector and acrylic. At the other end, because the flap that is bent, you can leave a little 1/2" slot for the air to blow out of as well. Now the output of the fan can blow across the entire length of the fixture evenly. I can easily feel the airflow at the other end of my 3' Tek light that I couludnt feel before.