I usually keep my water on the acidic side (around 6.0).
Plants in alkaline soil just seem to be stunted and won't take in as many nutrients as ones with a lower PH level. You can simply and easily bring down the PH with a little vinegar or lemon juice in your water. Use distilled water because it will be right around neutral (7.0).
Also, invest a little money in a test kit and it will make life easier.