very nice Hoppy!
i'm going have to order some acrylic tube and give this a try haha.
I noticed you now use 4 filters. Using the 6 you sent me orginally does the same thing correct?
No, with the 4 filters, the meter reads 10X PAR, so the 20,000 scale on the meter reads actual PAR. What I sent you made the meter read PAR, but not as accurately as with the 4 filters.
Look for a Rosco dealer near you and pick up a free sample stack from them, then you have enough of each of those 4 filters to make at least 4 meters. You could make a lot more, but then you have to worry about centering the filter stack over the window for the photodiode. With the 3/4 inch squares I used, the filters can't slide off far enough to be a problem.