my cycle so far, a few questions

[jess128]

I got LR in my tank on October 31. On Nov. 6, my water conditions were:
pH: 7.9
nitrate: 0
nitrite: 0
ammonia: off the chart
SG: 1.024

I tested the water again today (Nov. 20) and here's what I got:
pH: 7.5
nirtate: 10
nitrite: 2.0
ammonia: 0
SG: 0.023

I have been doing 1/4 water changes twice a week. I'm really glad my ammonia is down, I got some purigen from AI so I think that helped. My nitrate and nitrite levels were perfect, but now that the ammonia is down, they've gone up. Will they just go back down in time? I'm also concerned about the pH level. How can I raise the pH? Is it safe to add pH up to the water?