The last treatment to increase the pH was 29/1/2011 - about 50 days ago.
Our tanks are still full due to the substantial rain we have had.
The pH before treatment was 6.6 which, being below 7, is right for the Blue-Green stain to re-appear indicating that our copper pipes are dissolving again.
I treated it with 1L of lime and the pH rose to 10.6. This will drop as the lime spreads throughout the tank; as we consume the water; and as we collect more water.
In case it is useful, the water meter is on about 104kL.