Newt

I recently set up a 10 gal. shrimp tank and used F. Black Sand, a piece of mopani wood, and a couple of zebra rocks. I temporarily added some a few fish until the mosses grow out a bit and while waiting for the shrimp to arrive. I began having pH rise but not GH. The LFS said the zebra rocks were safe and I tested the larger one with Seachem Acid Buffer by dumping about a tablespoon on the rock and wetting it. I had no fizzing.
The pH rise has slowed down but still rises even thou I removed the fish (I thought I might be having a mini cycle even thou I used a filter from an establihed tank).
Is it possible the sand is my issue?