Edward wrote:
Deck will be off the house ten x twelve feet and six feet off the
ground.
I plan on using cones four feet into the ground, I figure a little
more then five bags of concrete per hole.( It is in a hard to get area
a concrete truck out of the question.

My question is what is the maximum length I can go using 2 x 8
pressure treated joists between 4 x 4 pressure treated collumns ?

Your local building department should be able to help you with
this. My county building department had handouts at the front door
detaling information for decks and basement finishes. They also have
engineers you could ask questions of during certain hours of the day.
I know in my case I had to go with 2x12s for a 12 foot span.
Mark