or do i keep it just to the bottom of the the netpot the whole grow?

The initial height could even be a little variable based on how active the bubbler/s are. If you used multiple stones and a good strong air pump the sparkle from the bubbles popping on the surface might even start you a little below the bottom of the netpot. After you decide on which equipment you want?..do a dry run (no plant) and see how moist the medium stays. That will influence your starting height.

same through out the whole grow.

My opinion varies from cigarettes a little. As the roots begin to become established in the nutrient solution?.allowing the level to fall some could be beneficial as keeping the root cube too moist could eventually cause problems. Lots of replies offers lots of methods??all have merit.

ah thank you very much. sorry a couple more questions, in a 5 gallon bucket, where is the 5 gallon mark? is it at the rim of the bucket? I want to know so I kind of know how many gallons I actually have in the bucket so I know much nutes to give them.

Place the netpot into the bucket and fill to your desired working level?..then measure how much water you used. (gonna be in the neighborhood of 3 ½ gallons with a 6? netpot)

and how much does the pH fluctuate day to day using only general hydroponics flora micro,gro,and bloom?

Only experience will tell

what do you guys do with the plant when you need to change the water?

Prepare a second bucket and simply move to the other bucket. (Be sure that the temperature of the solution is the same)

Good luck,
HMR