Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
What is the GH and KH of the source water?
Aim to get these right first, then worry about the pH. pH is not as important as the mineral content of the water.
To alter your source water before it enters the tank is a very good idea. I can think of a couple of ways:
This is more of an interrupted continuous auto-change:
1) Auto fill a barrel that has the minerals in the form of coral sand, oystershell grit, limestone sand or similar material.
2) Circulate the water in here for X hours (you will have to test to find out how long) before using it for the tank. The more of those materials you run the water though the faster it will work.
You would have to test to be sure it works, but:
As part of your auto fill routing run the water through a barrel that has a LOT of those materials. No pause to circulate the water, just pass it though as slowly as you can.
Simple, but not so great:
Set up a fish feeder to dose the tank a couple of times a day with GH booster and baking soda right into the flow of the incoming water or the flow from the filter (whichever is going to dissolve these materials fastest)
Similarly, there are ways to auto dose liquids with just a timer and a very small pump. There are liquid GH and KH boosters (Kent makes them, and I am sure other companies do, too)