Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
When you tested your tap water, did you leave some out overnight or longer, and test it after it was exposed to the air for 24-48 hours? Some tap water will change pH overnight.
Take samples of everything you have in the tank and put it into separate jars of water.
Test the water when you start, and every few days for a week or more. Have one jar with nothing, just water.
So you will have a jar with some substrate, a jar with a bit of rock, a jar with a bit of driftwood...
If you are adding anything to the water (minerals, pH regulating materials) do separate jars with each of these. Try to figure out the right dose (or run these tests in a larger bucket so you can get something close to the right dose).