Mike, you might check back with TSC--they do carry Cutrine here, now, but didn't for a year or so.
When you say you used three gallons of CP, it sounds like you are just glugging it out of the bottle into the water. I don't wonder that you didn't see much results. I dilute it and spray it on the algae, which I think is the recommended method; it is (almost) fun because it kills filamentous algae almost on contact and paddling around with a kayak the next day just dissolves it; of course, as Kelly points out, that does not eliminate the nutrient load in the water. In terms of spray methods, if things aren't too intense I use a backpack sprayer but sometimes I use a 12-volt sprayer on the tractor. If that doesn't have enough reach to cover your pond, you might consider a small, gas-powered pump (Homelite makes a decent one which TSC used to sell, and Honda makes a terrific 4-cycle model). You still have to have a stock tank or some such to use for diluting the product; TSC sells a 100-gallon one for about $80 or so. Finally, if you have a ton of algae to kill you must do the pond in sections, a week or so at a time, or you will add so much decaying mass to the water that it will deplete oxygen. Finally, I don't think that Cutrine will kill fish eggs or fry, but I don't know that for sure. I am pretty sure you can find the MSDS sheet on the web.
Also like Kelly, we use beneficial microbes to soak up nutrient load; you can actually watch 'em work on the surface stuff, and they do an amazing geometric population explosion which results consumption of considerable nutrient.
I also have several of a product called Aqua Mats, which are a sort of manufactured algae magnet--go to aquamats.com if you're interested. I am hesitant to recommend them because they are expensive and are not a silver bullet, but I do think that they help if you can stomach the expense.
We use our pond for swimming, and so I push the algae all the way back a time or two a year with Cutrine. We add microbes weekly and I also wad the stuff up if I run into it while swimming, and then add it to the compost bin or, sometimes, use it for mulch.
You've certainly gotten a passel of advice; I hope your head doesn't explode before you figure out some strategies which work for you. Good luck and best wishes!!
