proudgm, You, first of all, are not dumb!
Just new to this alchemy of ponding.
The only things I see are missing from this equation, there are not enough plants in the pond.
Leaving the filter alone to do it's job!
And most of all, patience! LOL

The pond water in the photograph, looks good, just a little green and that should go, given time and some plants to use up the nutrients in the water.

I would advise you to add more plants, do not use any more chemical solutions, and wait for nature to do it's thing.
The pond is going through a natural phase called "New Pond Syndrome" and you are going through the "New pond owner Panic Phase" who is in a haste to fix this problem NOW! LOL

Here is a tip from Norm Meck, a guy who knows about "Green Water" problems and how to tackle them. This is his method of inoculation, that aids in clearing up green water naturally.

If you know some one with a pond that has clear water [and no problems with the water chemistry or fish health] ask them for a cup or two of the sludge from their filter, mixed up with some of their pond water.
Take it home to your pond and pour it into your filter [or pond].
You have then seeded your filter and inoculated your pond against green water.
Then wait and see what happens. The first time I tried this, my pond cleared over night.
I just added a couple of cups of water/sludge I scooped up, from a local pond and it did the trick.

As to your question about the colander/basket cage suggestion, try the link below for more information and photographs, from myself and other members, on homemade pump prefilters.
Good luck with it and please get back to us on the outcome. Feedback is very important around here.
Thanks,
"Horton"

Here is a link that might be useful: Colander/basket prefilter posts.

Thanks! I will be building one today. Another question. The bioballs that I have in my filter were not new. They came from my old pond but were stored dry in my house all winter. Do I need to buy new balls? Did the helpful bacteria die out during the winter?

I see Cindy already answered your question in your other post, Good!
"Horton"

Thanks all for asking and answering this question again for all of us who are new to the forum. I now have ideas on how to improve my prefilter!

I've had my pond for 20 years now I guess but it needs some TLC and I'd like to see a pic of Hortons filter. Been looking and not finding one. Can someone help me please? I had to buy another pump a couple weeks back because our power went out and messed mine up. I guess it got weak and just couldn't pump the water up anymore. It's full of plants so you can see the bottom but loads of junk needs to be pumped out of the bottom and off the shelves. I have a shop vacuum with drain hole at the bottom but have NEVER figured out how to get it flowing so I could open that up and not have to keep filling the vac. ughhhh I could use that to vacuum it out with IF I could just figure out HOW.