If you've got a UV clarifier, you shouldn't be having trouble with suspended algae. The first think I'd do is check to see if the UV is working properly.

Is the goldfish digging the plants out of soil or some other fine substrate that might be clouding the water?

Totally opaque meaning you can't see the bottom of the pond, but you can still see through a jar of pond water, right?

Sounds like suspended algae. Removing the attached algae will have benefited suspended algae by removing competition for nutrients, but your water may have turned green anyway. Do you have any plants in the pond? Barley extract and filtering through quilt batting are good quick fixes for suspended algae. You could use algaecide, of course, but I wouldn't.

How old is your pond, and if it's a different question, how long have you been taking care of it?

Suspended algae is expected with a new pond, and though it will make your fish harder to see, it won't hurt them. As the pond matures, the water will probably clear up, however, it will likely turn green from time to time. Try barley straw extract to inhibit suspended algae. Many people have got their water clear again by filtering through several layers quilt batting. This can be rather labor intensive in the long run, but it's a good quick fix.

For a long term solution, you may want to use a very small bale of barley straw, but the extract will start working much faster. Adding more plants potted in cat litter and laterite rather than soil should help too, though it will take a while before you see the difference. A UV clarifier is another option.

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I'm confused about the pump which needs cleaning and from which the [other?] pump draws water. Could one pump actually be a settlement chamber fed by a bottom drain?

Does the new murk have a discernible color?

Filtering through several layers of quilt batting often works for suspended algae and silt.

Blue orfe are very large, very active fish. They need more room and more oxygen than your current pond can provide. They'll grow at least 2 feet long if cared for properly. Can you imagine a fast-swimming fish that size charging around your pond? Also, as they are shoaling fish, it's recommended that you have at least three if you're going to have any at all.

With only 16 inches of depth, you must be very careful of herons and winter, but your goldfish should be okay as long as you keep the predators off them and keep them from freezing. The rule of thumb is 30-50 gallons per adult goldfish, hence you can probably keep the five you have, but I suggest that you not add any more until the ones you have reach their full size of about 10-12 inches, not counting the tailfins. By then you'll know enough to make an informed decision on overstocking, and may well have built a larger pond.

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I put three good sized rocks in a 5 gallon bucket for ballast and pull the hair algae gently in hand over hand. I usually wind up wading and sometimes use a long handled brush to start the pull from the deeper sections. Many people hate it, but I like the stuff. The species I have is a nice shade of green and it's easy to remove the excess. I consider it part of my filtration system.

It's best to plan for the full adult size of the fish. Some will tell you that, "fish will grow to the size of the pond," but what that really means is that if your pond is not large enough, the fish will grow slowly, become stunted, or die when they get too large.

What kind of fish are they? And what sort of filter do you have?

When I used the chemical algaecide, it was only because I was restarting the pond in late fall and I didn't want a pond full of rotting algae depleting the oxygen all winter. The label on the algaecide said it causes cancer. That's probably in much higher concentrations, but why take the chance there are less toxic methods?

I just checked on the pond again, and not only is the surface clear now, there is only the slightest trace of foam in the skimmer, just a few transparent bubbles. The currents in the skimmer must have put the foam back into solution. There are no bubbles drifting across the pond from the waterfall either. The bubbles dissipate within about a foot, and after that, it's just clear water.

Hence I wonder if you weren't overfeeding after all. Maybe you or rain overfilled your pond. And as the water level dropped from evaporation, and skimmer started drawing from the surface again, the foam went back into solution.

Skasmo, I cleaned my filter and added some enzymes last night, and few hours after topping off this morning, my pond looked much like your picture. My first thought was the enzymes or something in the city water. But when I opened up the skimmer to scoop out the foam that sometimes collects on either side of the leaf basket, there was none.

Though the foam looked threateningly unfamiliar, it was just normal foam from pollen and whatnot. But my overflow had shifted slightly, allowing the the water to rise just above the skimmer weir. Hence, the skimmer stopped skimming the surface, allowing the foam to build up, and a small amount of foam that would normally go unnoticed appeared to be a major new problem.

I'm not sure if this is relevant to your situation, but my foam looked exactly like the stuff floating on your pond.