Take your eight cups of cranberries and squish them. Which is actually popping them. Son of a gun, I looked like I was blood splattered after this part of the recipe, it looked like something out of a horror movie. The berries do not squish nicely, they explode. What I finally did was take a cup and use the bottom to mash them, not only did it help keep the bloody cranberry gore splatters from flying everywhere, it popped them better.
Add the water into the pot and boil the berries for 10-15 minutes. This part is stinky, they don't emit a very pleasant odor when boiled. Or at all actually. When we picked them I actually smelled the berries first, so I started looking for them while we walked. It sounds rather Les Stroud of me, but in the fall when you are walking in the bush and smell something that is worse than your gym shoes? That's fall ripened cranberries.
Once they are done boiling, strain them through a cheesecloth. I put the cheesecloth over a colander, then over a pot, works beautifully. Once it cools enough, you can lift it up and squeeze the remainder out of the cheesecloth. You will get a good 5 cups of juice, and to this add your sugar.
Time to boil it up! Once it's boiling, stir in the liquid certo. Bring it back to a full boil, then boil it hard for a minute or two, making sure to stir constantly.There will be foam on top, so skim it off. I have found that if you let it sit for a couple minutes, the foam forms a skin on top, making it really easy to scoop it all off cleanly. You do want to try and get it all off, when making a jelly it's so crystal clear that foam bits show up as floaties in the middle of the jar.
Pour into your sterilized jars, leaving about 1/4 inch left at the top. Make sure that before you put the lids on, wipe the rims as clean as possible, because this is is the number one reason they won't seal when you put them in the canning pot and boil them. These needed to be boiled in the canning pot for 10-15 minutes.