Thought I'd share a very simple setup we use to generate gallons and gallons of rich compost tea to use widely in the garden. Less than $40 to get going, and 3 watts of electric to keep it aerated... Let me know what you think.
I'll answer a few things here...
mosquitoes... they come around but with birds and such they aren't a problem yet, so we haven't had to think about another design layer. Could have a fitted sheet that goes over it if it becomes an issue.
advantage over your ideas, Dale... I find it nice to have freely available nutrient water to dip into any time I want to water. Makes it more likely that I'll use it if it's super convenient and always 'on tap'. I'm not sure there is a technical advantage, but I like it being there and ready for me.
Todd... I am still experimenting with timing, but so far a day or two and it seems like it gets started on being rich. A week now and its very robust and strong. I've diluted it down once and still has a rich color. I'm not scientifically minded so I can't say whats ideal, but by feel and how the plants respond it feels like day 2-5 is a sweet spot window.
What advantage do you think this has over composting on the ground or in a garbage can, and then mixing the finished product with water, just before it is delivered to the plants?
Compost Tea was recently popularized by Elaine Ingham. I'd describe her as lady who loves looking at compost through a microscope. The purpose of making tea is to greatly increase the number of beneficial organisms. We know that beneficial organisms love aerobic conditions, and need food — so we take some compost, add it to a bunch of water, force air through it, and add a little bit of food. This bubbling action increases the number of beneficial organisms by orders of magnitude compared to just making a slurry with water (your second question).
But from my research into compost tea, your first question is one that has yet to be definitively answered by anything peer-reviewed, but widely used here in California in organic farms for high value crops (think Humboldt county…). It's been difficult to measure the effectiveness of compost tea over on-ground composting because compost quality varies so widely. It's very likely that just by watering compost on-ground, the same explosion of beneficial organisms happens inside the soil since it also provides aeration and food — it's just unreasonable to count the organisms in the soil via microscope (since they are spread unevenly), while it's easy to do with a bottle of liquid (where they're more homogenous). One reason people usually prefer tea over on-ground composting is that it's easier to scale. I know a few people with 10,000 gallon aerators hooked into irrigation. That way, you get a lot of the same ease of use of chemical fertilizers without any of the chemicals.