Halfway through week 4, and moving along. I solved the last two problems I was worried might trip me up on Monday, making sure the cameras could actually focus on the surface of the glass and weren't too far away, and getting enough light to a microscope immersed in a container of seawater so that I could actually see things underwater.
It's always the little details like this that you don't really think about until the last minute, when you are hooking the webcam into the camera and thinking "So this is going in a tank of water- where's the light coming from?" And then you hope you're creative enough to find an answer to a problem you didn't realize existed until moments before, but might wreck your whole experiments. So far, I've been lucky/creative enough to not have anything permanently trip me up yet.
I tried a trial test run on Tuesday, where I let an algae release spores and then tried to take pictures of them with the webcam. It seemed to work, but I never found the spores with the microscope. They either never were released, got blown off when I assembled the flume, or (most likely) were just too dang small and sparse to find on my giant sheet of glass. I think with a little more care, I should be able to find them, hopeful this won't be the devilish detail that wrecks the whole project.
In any case, here's a picture of my more or less finalized setup:
I made markings to tell where I was on the glass:
And was able to see the marking through the webcam, onto the computer: