Why do a Water Change?
Yes, you really do need to do water changes. We, luckily, have a toilet to take care of our business. But fish, coral and other invertebrates don't have this luxury. In order to keep toxic levels of nitrates from rising and other algae-loving substrates like phosphates, water changes are necessary.
How Much? How Often?
Everyone has different recommendations but I like to do ~15-20% bimonthly. I've heard of anything from 10% weekly to 20% monthly. It all depends on your bioload (how many fish you have) and equipment (a nice media reactor and protein skimmer cleans the water for you, making water changes necessary less frequently). In my opinion, I prefer smaller, more frequent changes. It's not as stressful on the entire system. A big change may shock your fish. Saltwater species are sensitive to any change in their environment. Afterall, they're used to a big, stable ocean. It's a bad idea to throw out a bunch of water they're used to and suddenly give them a bunch of new water, no matter how closely matched the new water is to the old.
- 30-40 gallon garbage can on wheels for mixing saltwater (with lid)
- pump for mixing saltwater and pumping water into or out of tank
- plastic tubing (attaches to pump and long enough to reach tank from garbage can)
- high quality synthetic salt (I love Tropic Marin but there are other good ones out there as well)
- heater to heat new saltwater in garbage can to match that in tank
- thermometer to measure temp of saltwater in garbage can
- refractometer to measure specific gravity (salt percentage)
- sponge, scrubbing pads, old toothbrush, turkey baster and razor blades for cleaning algae off live rocks, substrate and sides of aquarium
Step-by-Step Water Changing Procedure:
- Mix salt water, preferably 24 hours before use:
- Pour desired amount of RO water into garbage can (make sure you have extra RO water as back-up in case you overshoot specific gravity)
- Hook up pump to plastic tubing to circulate, turn on heater, put thermometer into garbage can.
- Slowly add salt a few cups at a time. Usually ~1/2 cup/gallon for a specific gravity of ~1.025. Allow each batch to dissolve (this is what the pump and tubing is awesome for) before adding new batch (~10-15 minutes). When you get close to total predicted amount of salt needed, begin measuring specific gravity with refractometer. It's always better to undershoot and just add more salt than overshoot and have to add more RO water.
- Check the temperature, pH and specific gravity. Adjust until these parameters are identical to your tank.
- Clean aquarium:
- Turn off pumps, powerheads, protein skimmer, etc.
- Use scrubbers, pads, toothbrush, etc. to lightly clean debris and algae off sides of aquarium and live rock. Be careful not to disturb fish and coral! Leave some green algae as "tang fodder". Gently mix top 1" of substrate with fingers to dislodge algae. Don't overmix or go deeper than 1" or you will disrupt the beneficial anaerobic bacteria underneath the top surface.
- Wipe off salt creep from outside edges of aquarium.
- Empty protein skimmer cup and clean out skimmer.
- Change carbon in media reactor, if necessary (monthly).
- Change filter sock.
- Remove 10-20% old water:
- Our tank is 75 gallons so this is 8-16 gallons for us.
- We use the same pump used for mixing saltwater connected to a long stretch of plastic tubing. We put the pump into the top of the aquarium and pump it through the tubing into a 2nd garbage can designated for waste water. Try to get up as much of dislodged debris as possible.
- Add new water:
- After carefully making sure the new water matches the aquarium water (pH, specific gravity, temperature or as I like to call it, "PST"), use the pump and tubing to pump water from fresh salt water in garbage can into aquarium.
- Turn all systems back on and check to make sure everything is running properly.
- Leave a fresh chocolate mint on your fishes' pillow.
Your fish will thank you!Links on Changing Water in a Saltwater Aquarium: