There was much buzz at MACNA this past September when the Guardian Pro prototype was demonstrated at the show.  Developed by Dr. Bridge, the KH Guardian (KHG) could become commonplace in higher end reef aquariums everywhere. Reef aquarists know that keeping alkalinity stable is important, but what is alkalinity?  Alkalinity is a means of quantifying the stability of pH in aquarium water; it measures the concentration of various negatively charged ionic compounds (anions) such as carbonates, bicarbonates, borate and hydroxides in the aquarium water. Although testing alkalinity is a simple and affordable test, there is still a chance of user errors and misreads. Alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. If left unchecked, alkalinity can drop below a critical level and pH MORE