Bandit....soil expands with moisture and will shrink with a lack of moisture. When the soil dries out it will leave a gap around the perimiter of the pot itself due to shrinking. This is how i know it's time to water. I know this holds true for lots of potting soils, but maybe not for yours...I have never used the same soil as you have. Most important thing is to water till the soil is saturated allowing excessto run off and then giving the plant time to soak up all the water before adding more. You will notice a HUGE increase in your plants' health over the current method you are using.