Wierd pond pump behavior

[spence]

I left my new pond running as long as I could this winter, eventually having to shut it off when the ice buildup was really extreme in December. I left the pump in my skimmer though, thinking there was no way it would freeze more than a few inches.

When I tried to start it up a few weeks ago the pump acted in a very wierd manner. Basically it would just push a trickle of water. If I disconnected the hose and let it run inside the skimmer it would push a little water for 5 minutes and then increase to a normal flow. If I then reconnected the hose it would operate as normal for 5-10 minutes and then return to a trickle.

So I left it shut off the past few weeks.

Today I started it up again and it took a while but it's been running all day just fine.

Any ideas on why it would do this? I'm pretty sure there was no blockages anywhere.

On a good note, all my fish survived even though my pond isn't terribly deep and was iced over for several months. I did use one of those floating heaters so there was always some open water.

-spence