Water Changes - They're Awesome! - Captive Aquatics: An Aquarium and Ecology Blog

The most important husbandry practice and the best way to insure the health of your fish and invertebrates is also one of the most simple: regular water changes! I feel that water changes are an underrated, especially with all of the filters and gadgets now available to aquarists. However, water changes still remain the #1 way to improve water quality, and to maintain low dissolved organic compounds (DOCs).

Water changes are the key to happy, healthy aquatic animals in fresh or saltwater aquariums. Water changes reduced dissolved organics (including but not limited to ammonia, nitrites, nitrates, phosphates, and other organic wastes), replace trace elements, dilute wastes already present, provide greater water clarity, reduce acidity and restore buffer compounds, and in saltwater aquariums replenish calcium, magnesium, and other vital trace elements that are important to coral growth. No filter, protein skimmer, ozonizer, or any other device can provide high quality water for months at a time. Regular partial water changes are essential!

Many sources state that a 10% water change a week, or 25% a month is ideal. I completely disagree - after decades of keeping aquariums, I recommend much larger and more frequent water changes! In smaller aquariums (less than 100 gallons) I perform 50% water changes twice a month, with excellent results in health and growth. In larger aquariums (over 100 gallons) less frequent water changes are often preferred due to the large volume. These are the only aquariums where I feel that once a month is adequate; and I recommend at least 1/3rd of the volume be changed monthly. In nano reef and other small aquariums, 100% weekly or bi-weekly is the way to go - I regularly drain my nano reef to the bottom, and then refill. When performing water changes of 25% or more, ensure that water temperature, pH, and salinity (if applicable) are an exact or similar match to the tank water! Ensure to aerate and dechlorinate your tapwater, as well.

Water changes don't have to be difficult: devices that attach to the faucet for emptying and refilling make the process much simpler. If you have a marine aquarium, buy a large plastic tub in which to aerate, adjust temp / pH, and mix the saltwater prior to the water change. A pump with a threaded outlet + garden hose adapter for the pump outlet + a Python clean & fill make this process much easier!

Bottom line: water changes are one of the best things you can do for your fish!

Like this? Please bookmark via the social bookmarking buttons below, subscribe to our free RSS feed, and sign up for our free weekly newsletter on the right!