Did my testing,,I think I am almost cycled,but have a few question

I set the 135 gallon tank up last Saturday evening,my testing today shows a low ph of 7.8 I added buffer but I am still having a hard time with the ph.The tank evaporates almost a gallon of water a day and I add buffer to the gallon I add back but can't seem to keep the reading where I wont it.How much buffer should I put in the gallon I add to the tank?.
My ammonia was at 0 nitrites are a 0.25 and nitrates are at 5.0.. I am waiting for the nitrites to hit 0..Is the nitrate reading of 5.0,OK?
I have around 27 pounds of base rock,and 37 to 40 pounds of live rock..As of right now anyhow..I put in 80 pounds of aragonte sand and 40 pounds of live sand.

Also wonted to ask..I don't have bio balls in the sump...WHat I have a balls..but they aren't what I would call bio balls,,the balls I have some have a ceramic in them some have carbon and some have filter pads.they are Bio Mate Refillable Media Balls.I was going to leave the in the sump for awhile and slowly take a hand full or two out a week or so till they are all gone and replace it with live rock..Good idea or not..and could i just leave the balls in from now on?

A link to the type of balls i have in the sump http://www.pentairaquatics.com/2005_aquarium/Aquariumnew.html