[MikeM]

In another thread a question was asked about oak leaves settling in a pond over winter and the effect on water quality. I thought the topic deserving of its own thread.

I have no experience with leaves over-wintering in a cold winter climate, so I'll let others comment on that specific question. I can comment on my personal experience with leaves. Before Hurricane Charlie reduced the tree cover in my garden, my old pond had leaves dropping in continuously... and pecans, acorns, bloom tassles from oak and pecan, camphor tree seeds, etc., etc. I got into the pond every week to get it all out. After the hurricane, there wasn't much to fall in. The water quality improved greatly. Even with weekly removal of everything that fell in, I could not get nitrate levels much below 20ppm, even with 50% weekly water changes. At times nitrate would rise to 40ppm. During pollen season I'd not even bother to measure it. After the trees were gone, nitrate stayed below 12ppm.

I have a little puddle pond where I keep guppies. From November through April the guppies are brought indoors and the pond is ignored. It does get a load of leaves and debris to be cleaned out in late March. The water turns brown from the tannins. The pH sinks to as low as 6.0. And, when I clean it out in March, the rotting debris is foul. A little pump continuosly recirculates the water to prevent mosquitoes from breeding, but the smell of hydrogen sulfide from anaerobic decomposition in the bottom is nonetheless quite noticeable.

No matter the season, I think it important to keep the water in great condition if you are keeping fish in it.