Although many freshwater fish-keepers may disagree, saltwater tanks require a little extra attention to maintain water quality. Here is a quick guide to what you need to do regularly to keep your tank in shape.
There's a lot to keep in mind so it's a good idea to start by keeping a calendar or notebook to track what you've done, especially for procedures that need to be performed only occasionally. It's also important to note water quality, what you add to your tank and how much (including brand name and manufacturer), as well as anything out of the ordinary. This way, you have a record that may help you predict a potential problem or allow you to backtrack to figure out what may have happened if something goes wrong.
Check your pets to make sure that everyone is happy and healthy. If you notice that a fish doesn't look right somehow, keep an eye on it. Dead animals will destroy water quality because as they deteriorate, ammonia increases to dangerous levels.
Clean the protein skimmer cup. Skipping a day once in a while isn't a problem but be sure not to miss more than that.
Check the water temperature and make any adjustments.
Remove any uneaten food.
Take a quick look at your equipment and accessories. Make sure that all the equipment is functioning correctly and accessories, such as in-tank thermometers, are still in place. After a while, you will know your system well enough to anticipate problems. A pump may begin to make a funny humming sound that you never heard before. Be aware of such subtleties and remember to make a note of them.
Every Other Day
Fill in any evaporated water.
Clean off any algae growing on the glass.
Perform partial water exchanges (10-25 percent of the total volume of your tank). You cannot keep a marine aquarium healthy without partial water exchanges, unless you have a system that is directly connected to the ocean. Water exchanges can also be done bi-weekly, but this depends both on how well you maintain your system overall, as well as what sort of creatures you have.
Clean the glass and remove any salt build-up around or on the tank and its systems, (including the lights!). If you don't do this regularly, the salt will build up in rather large chunks and could fall back into the tank, wreaking havoc with the salinity. Salt is also incredibly corrosive to various metals. Cleaning them regularly will help keep them functioning correctly.
Add any trace elements, pH buffers, conditioners or vitamins.
For new tanks: test the water quality including salinity, ammonia, nitrates, nitrites, pH, and specific gravity. Keep a record of these parameters to see how your tank is doing. If you have an established tank, or once you notice that there is little change, you won't need to test as often –- biweekly will do.
Every Two Weeks
Replace the filter floss in canister filters
Test the water quality. If you are just getting started, test the water weekly.
Siphon through corals and substrate carefully to keep it clean.
Clean the protein skimmer (not only the cup).
Check all hoses and tubing connections and make sure that assembled parts are secure and stable.
Replace or clean airstones, depending on what you have, and change the carbon.
Every Three Months
Clean filter canisters and hoses inside and out. Check to make sure that all hoses are clear by blowing into them. This is important to prevent any backflow, which can damage your equipment and, depending on your set up, cause flooding.
Change air pads in air pumps.
Every Six Months
Check for damaged pump impellers. Replace them if necessary (it's often necessary).
Change air valves. Air valves prevent any pressure build-up, which may damage your pump and other systems.
Replace UV tubes (if you have a UV filter).
Replace lighting system bulbs, whether they are blown or not. You may not think the bulbs need changing, but lights lose their intensity over time and, especially in the case of a reef tank, the light quality is one of the most important variables for your marine pets.
Some may consider these guidelines to be excessive, but only you can determine, with time, what is best for you and your fish. Roughly following this maintenance schedule at first should give you a general idea of what to do and when to do it to keep your own tank healthy.