Canada has new laws sharply limiting phosphorus in dishwasher detergents because phosphates are harmful to fish and plant life. So how do the new "greener" formulas perform?

When Consumer Reports last tested dishwasher powders, tablets, gelpacs and liquids the detergents with phosphates typically cleaned dishes the best.

This time, testers evaluated 24 low-phosphate detergents. One even claims it "powers away 24-hour stuck-on food."

To see whether they deliver, Consumer Reports subjects the cleaners to some tough tests, a lot tougher than your daily dishes face.

Testers apply an extra sticky mix made with 17 foods including peanut butter and Cheez Whiz. Then the dishes are cooked in the microwave to make the goo stick.

Pots are coated with macaroni and cheese. The same number of dishes is washed per load. Each detergent is tested not just once, but three times.

"The worst performer in our test left a lot of food," Consumer Reports' Bob Markovich said holding a plate still caked with goo. "You wouldn't want to eat off this plate."

But overall, the new generation of green cleaners did much better than in the past. Testers recommend four that are "very good" at cutting grease and removing food.

"But think twice about buying a dishwasher detergent by brand," Bob Markovich said. "While Cascade and Finish were among the best in our tests, they also had some of the lowest-rated cleaners."

He said performance was product specific with tabs and pacs consistently outperforming powders and gels.

In the end, Consumer Reports named Finish Powerball Tabs a best buy. The tabs did an excellent job cleaning dishes and pots at a great price. Cascade ActionPacs with Dawn were also top rated.

You can expect to see even more green or phosphorus-free dish detergents on the market in the coming months. With the new laws in effect here and in many American states, manufacturers are scrambling to bring out even better formulas.

With a report from CTV British Columbia's Chris Olsen