I would say leave it alone and wait...you may try some quilt batting in the filter...but, I think the cloudy water is just due to the massive water change which means more nutrients for algae to grow---with all your hornwort you were starving out any algae---now that you took alot out and cleaned out the pond you are starting from scratch again---looks like you may be getting ready for an algae bloom....
Lawanna

In addition to the excellent comments by Lawanna I would add that you may want to consider reducing the number of fish in your pool. And adding more water lilies that will cover up to 50% of the pool's surface. Also increased aeration of the pool by adding an aerating strip or bubbler and possibly even putting on temporarily an independent filter For a low cost add on check out the
Tetra line
Tetra filters

Because your pool is fully exposed to the sun I am wondering if you track the water temps during the day and night? I had the same problem with an in-ground pool until the trees I had planted grew tall enough to shade it. That is why the suggestion for more water lilies!

Patience Grasshopper..........
One thing you might do is clean out your filter more often. Other than that, its just going to take awhile for that balance again.

Quilt batting as a prefilter workd for me, but yes - patience - you WILL get an algae bloom 'til the plants get a chance to help you. DON'T do huge water changes or drain and clean it (I know you already know that), give nature some time. You can add a bunch of water hyacinth for now and remove it later when it tries to overtake the pond :)

What does it mean by "gravity flow, cannot be pressurized? I was looking at the Tetra filter link above. .I have a filter in my pond with batting and have to change it about once a week. It does a good job of keeping the water clean but am thinking an out of the water filter might be the way to go. .With the tetra filter would I have to have a bottom drain? Thanks. .Debbie

I would say that what you did wrong was to "clean" a perfectly balanced pond.

It is going to take a while to get it back in balance.

I can't agree wholeheartidly with buyorsell this time. I don't think you did wrong in cleaning your tank. Thats's just MHO. I think you did well to get the gunk off the bottom to keep all those bad bugs from having a place to grow and multiply. You just need to have patience. When I re-built my pond last year it took about 3-4 weeks for it to get real green and about the same length of time to clear. And has been clear ever since. When I drained it this year to get rid of the bluegills; I pumped about 600 gals from the pond to a stocktank. I kept my fish in this while I cleaned out the rest of the pond. Then I put most of this water back into the pond through a filter and then finished filling it with our well water. It has been a month and remains very clear all the way to the bottom 5 ft depth. I know it's hard to wait, but that's what you need to do. I re-potted my lilies and they are growing, but haven't started to do much covering yet. And my pond is in full sun all the time, so far. Glenda

I think cleaning the pond (which we all do at some point), is like pulling out the bio wheel on an aquarium and putting a spanking clean new one in. It will just take time. Hang in there!