I once thought that the nastiest household chore I have to do (and this includes all the cat-related gross stuff) was unscrewing the rosette from the bathtub drain, taking a plastic strip with hooks, and going fishing in the drain for hair logs.
It turns out I was wrong. There is now the chore of unplugging the pond filter once every two months, reaching into the pond, and lifting out the filter in order to open it up and clean out the string algae growing on and in it.
This is the inside of the filter. The brown thing in the middle is essentially a panty hose full of charcoal, and I have to find where I can order another one because they gunk up after a while.
I've tried doing this cleaning with gloves, but I just don't have the manual dexterity to do it gloved up. So barehanded, I lift out the pump and dump it on the lawn; and then with a hose and a brush I scrub off the algae, picking off the worst lumps with my fingers. String algae grows fast. It looks liked cooked spinach and is the slimiest thing ever; it's like a horror movie prop coated with boiled okra. It does make good compost, though.
The pond store does sell algicide that you can put in the water, but after reading the label I put it back on the shelf. I may run the UV light for a few minutes once the weather gets cold, though, just to clean out inside the filter.
The Poser mermaid is Lagoona for V4 (like the Monster High doll) and is by Silver and Adiene over at Renderosity.com