How can my pond be this bad?

Watergarden's advice is spot on and definitely shift that pump up off the bottom (and turn the power down). You won't need the UVs on until next Spring.

 

Oh god, I've been doing it all wrong for the last 22yrs.

 

The link to the pictures is much better. Thank you.

It is also true that at this time of year some pond owners raise the pump so its not in such cold water.
This "intricate operation" is carried out by "sticking it on a couple of bricks" This also has the benefit of reducing the amount of debris near the pump.

A thing to do in spring is to clean the pond, some folk use a pond vacuum for this.



Other brands of pond vac are available.

If not you can always pump the water to a temp pond and use a soft dust pan and brush. I am NOT joking, its surprising how good it is. (Dust pan with a rubber "balde" on the end is very good)

This one has.

this one hasn't

 

Today the pond is a grey colour. I suppose this is a nice change from the normal greeny brown or browny green!

I've turned off the air pump and moved the skimmer (it was very close to the pump).

I will raise the pump using the brick technique you recommend later

The pump is at the opposite end of the pond to where the waterfall returns the water from the filter. The skimmer is now about halfway down one side.

For my next stupid question ... when I clean the filter foams in pond water is it simply fill a bucket from the pond, rinse the foams a bit, pour the water on the garden and refit the foams? I've been using a pond vacuum to draw the dirty water out of the filter, is that a good idea or not?

 

Hello John Kitching, no question is stupid, if you don't know you ask, which is what you are doing.

Filter foams get clogged, so the idea really is get a bucket of pond water (doesn't have to be a bucket though, a storage box is fine) and shake and rinse (if you see what I mean) do them one at a time, so you have more room in the bucket to move them about.

You should never clean the filter media, so presuming that is what you have been doing its a bad idea as you remove the good bacteria.

In a normal working filter the sponges or what ever filter media you have collect / trap 99% of the dirt so the media is just media and pond water, pond water which feeds the multiplying bacteria.

Never be afraid to ask.