I just discovered a pricing anomaly on GH and KH test kits. That Fish Place sells a Aquarium Pharmaceuticals KH test kit for $5.00, which has 37ml of test solution. They also sell the combined GH and KH test kit for $5.00, which has 37ml of GH and 37ml of KH solution. The GH and KH readings on tap water match the water company specs. Sherlock Wong