First off, how old is the pond that has the algae problem? It is not unusual for a pond to take up to 6 months to "break in". THat is when the algea on the sides of the pond out compete the floating algea that is turning the water green for nutrients and starves it. Over night you will have clear water where the day before you could not see anything.
Oh by the way, quit cleaning it out. The only thing that needs cleaning is the crap off the bottom. Leave the algea coats on the sides and bottom alone. They are your best friend when it comes to a ballanced pond.
As for the mud pond with the "green turds" floating around on the top. IF you will notice, they appear usually more during the day, then at night, sink back to the bottom. A fountain or other air producing mechanism like air diffusers work very well in this type of pond. They are a bit pricey but worth the improvents they make on a pond. Personally I like the fountains better, but then they do cost about 50% more than the bottom diffusers.
The reason they keep dying is the algea. The algea produces O2 during daylight hours, but over night, it takes the O2 out of the water and releases CO2 in the form of carbonic acid. This is no good for fish. So if he wants success with fish, he will have to add some additional air to the pond.
As for losing the water, he needs to pinpoint where the water is leaking from. The narrower the area the less costly the fix will be. There is a good Sodium Bentonite clay that you can put in over the top, and in most cases it will seal the leak pretty good. The 50 pound bags run about 8 bucks. But you have to get the good stuff. There is a lot of crap that is sold as sealer sodium bentonite clay, and some is used in well drilling also. It is also not meant for sealing ponds.
There is a company that can add some chemicals to the water, and they get between 60 -80% inprovement with the leaks, but that is a whole pond treatment, and is costly. But if you dont have a clue where the leak is, that would be the way to go.
Hope that helps.
d