ph dropping during cycling new live rock tank

[susiQ]

My ph has dropped from 8.1 to 7.8 in three days. I can not read the alkaline measurement with the current tool I have and the Nitrites are running between 2-5ppm.
How do I get the Ph up? and how do I accurately read the alkalinity of this 55 gallon tank. I have no fish in and in my 2nd week of cycling the tank. Help please...thank you SusiQ

 

[bertoni]

A low pH during the cycle is common. A lot of the decay products are acidic. You could do some water changes to help.

What kind of alkalinity test do you have? I would think most of the standard kits would work.

 

[Randy Holmes-Farley]

Limewater is a good way to maintain pH and calcium/alkalinity through cycling.

This article has more

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm