Summertime is about to reach its peak, and while most people focus on keeping water temperatures at optimal levels, it’s important to also keep an eye on dissolved oxygen. As water temperature rises, the solubility of oxygen gas in water decreases. This means that your fish and corals may not be getting the oxygen they need, which may cause them to be very lethargic and perhaps even die. Fortunately, adding dissolved oxygen to the aquarium is easy to do. Bubble pumps are readily available, and protein skimmers are always cranking out air. It may not be the easiest parameter to test for, but some aquarium controllers have special probes to measure dissolved oxygen.