That is a really small pond. How many goldfish do you have? That size pond would really only support one goldfish, for optimum health. And a small one at that, I think. And do you have some sort of shade for the pond so that it is not in full sun? At least some floating plants? That size pond will heat up really fast. Do you have an aerator of some kind? You should have some kind of filtration system to keep the water clean and aerated.
By water parameters, what mattmartindrift means is your ammonia/nitrate/nitrate readings. You will need a liquid test kit. I think the most common brand is API, and it costs around $25.00. But it will last you a very long time. How old is your pond? Did you add something to neutralize the chlorine when you first added the water? You should always do that, because chlorine will kill fish. Exactly how did you "clean" the pond when you did so? You shouldn't empty all the water out at once, as already mentioned it just starts the cycle over. And I wouldn't recommend chemicals to kill algae, it can be bad for the fish. My pond is about 800 gallons, and I add something called "Microbe-lift" every six weeks or so, which has naturally occurring bacteria that keeps algae under control. It's a liquid. Some ponders don't even like the use of Microbe-lift though, preferring to allow algae to disappear naturally. I never had much luck with keeping my water from looking like pea soup naturally though, despite a lot of plants. At any rate, I am not certain what to suggest you do now since you added chemicals.I would do a partial water change if I were you, about 25% right now, and be sure to add something that neutralizes chlorine.
I hope someone will have some better advice for you. Eek, re-reading this I sound very long-winded, my apologies! I'm just trying to help.