How to Do a Water Change

One of the basic maintenance procedures for keeping a successful saltwater aquarium is the water change. This how-to will show you the basics.

Instructions

Difficulty: Easy

Things You’ll Need:

• RO/DI water
• Salt mix
• Storage container
• syphon hose

1. The author's auto storage/mixing/waterchange setup On average, you should change 20-40% of the water in your aquarium monthly. If the tank is heavily stocked, or your fish create a lot of waste, the water changes should be performed every 2 weeks.
2. Fill your storage container or buckets equal to the amount of water you plan to change with RO/DI (reverse osmosis/deionized) water. Add the correct amount of salt mix (usually 1/2 cup per gallon, check your specific brand) and drop in a small powerhead to mix the water overnight at the least. The target range for salinity is 1.020 -1.023 using a hydrometer to measure specific gravity. If you have a refractometer even better!
3. Adding anything but RO/DI water increases the chances of introducing algae, bacteria, sulfates, phosphates, silicates and a whole host of nasties into your beautiful aquarium. Use only the purist of water and you'll have a solid foundation to help the tank succeed.
4. If you are doing the water change in the colder months, adding a small heater will be necessary to bring the water temperature up to the same as the aquarium. This will eliminate stress to the tank' s inhabitants.
5. Shut down the return pump, powerheads, heaters, chillers, etc on the display aquarium. This will keep any equipment from burning out due to lack of water movement.
6. Siphon out the desired amount of water from the display aquarium. There is much debate on siphoning the substrate of the aquarium, many beneficial organisms live within it aiding in the natural filtration cycle. If you have large, messy eaters in the tank it may be worth while to surface skim the substrate to pick up detritus.
7. Gauging the correct amount of water to siphon out on the first try can be a little tricky. Once you know the proper level to siphon, mark the tank in an inconspicuous place with a black marker so that next time there will be no guess work.
8. Attach the siphon hose to the powerhead used to mix the salt water. Use it to return the freshly mixed saltwater into the aquarium. Aim the tube against the glass to avoid stirring up the substrate and knocking over live rock and corals.
9. Fire up the system equipment and check that everything is operational.
10. Thoroughly clean all the equipment you used to perform the water change in clean fresh water and let dry.

Tips & Warnings

• check the salinity before adding the mixed water to the tank
• NEVER add the salt mix directly to the aquarium
• Use only the highest quality RO/DI water
• Watch for spills!