Jay,

First of - Thank you for taking the time to document/write up what you ave, and bringing pictures.

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I'm wondering, and please clarrify -
I was under the impression you were running an Algae Turf Scrubber - this seems more like a refugium w/out sand/rock to me.

As far as I understood with limited research that an actual Algae Turf Scrubber was a Horizontal "screen" that one grows certain algae species on, and water flowed over. I believe people run these several screens up (deep) .... part of maintenance on these setups is scrapeing the algae "turf" off on a set interval.
From my understanding these filtration setups have become a little less popular due to the "Gelbstoff" yellowing component the algae releases ... since people seem to love crystal clear water. Another prohibiting factor on these units, if i remember correctly) was that the design, and original concept were patented and rather steep royalties were request from the patent holder which made it less economic to comercialize the sale to hobbiests.
I think most people run these systems skimmer less as well - i could imagine that reason is to fuel the algae for growth, and therefor provide better nutrient export. Kind of like how younger trees produce more exygen than older trees. (just speculation on my part)

Again, that is what i understood, from limited knowledge - correct me if I'm wrong please.

Non-the-less, you are running a nice algae scrubber that seems to work for you.

--marco

"Give a man a fish and he will eat for a day. Teach a man to fish and he will sit in a boat all day and drink beer."

Very interesting, very interesting! Has there been any conversation on the benefits/problems with long term sun exposure to aquarium water? I do know that it will promote different types of alge growth that you wont typically get with artificial light. again Very interesting.

"Remember that no matter where you go, there you are"
Bukaroo Bonzai

Marco and Tlytell,
Thanks for the comments; you raise great points. First, I'm no expert so the info that follows is just from what I've gleamed by surfing the Internet. I found lots of different designs for what people call algae scrubbers. Like Marco points out, the classic design is a series of parallel screens, meshes or eggcrates, covered in growing macroalgae. Some are oriented horizontally, some vertically, some in tubes or canisters, and some with both lighted and dark areas. I think there are three basic features to an algae scrubber: 1) large surface area to allow large amounts of algae growth, 2) low flow so that there is significant dwell time, and 3) routine harvesting of the algae. I could line up a series of parallel eggcrates in my device, but I question how much more surface area I need since the thing is so big. Anyway, I call it my "algae scrubber" because it's so much cooler than calling it my "sump filled with algae."
Regarding the yellowing and discoloration of the tank water, I am very concerned about that. That's why I plan to get rid of the caulerpa and go with chaeto only. I think that will reduce the risk but I'm not totally sure.
The natural sunlight question is interesting. I have no idea if this is good or bad. I'll see if I can dig up some info on that.
Thanks for the comments. Jay