A pH monitor may reveal reef tanks with a pH as low as 7.6 at night. Employ these five simple pH hacks to raise your pH to 8.2 and above, and watch your corals survive and grow much better than before.
Get a protein skimmer
Protein skimmers are pre-filters that help reduce nutrients in an aquarium but can also increase pH. Mixing tiny air bubbles with your tank water dissolves the air into water, adding oxygen and helping to gas off and increase the surface area of the water. Fit a pH monitor, monitor pH over 24 hours without a skimmer, and then with a skimmer, and you will note a several-point increase in pH. It’s one of the many benefits protein skimmers bring to a reef tank.
Get a CO2 scrubber
The air that a protein skimmer dissolves all depends on the air that is present in the room the tank is in, and in a busy house with lots of pets and people, but the windows shut, carbon dioxide builds up in the house. The skimmer then draws in the air and dissolves the CO2 in the water, reducing pH, or at least not achieving the pH the skimmer could achieve with fewer people and all the windows open. Co2 scrubbing media can be purchased and placed within a simple dry reactor that is then connected to the air inlet of the skimmer. As air is pulled through the media a percentage of CO2 is stripped from it, meaning less CO2 is dissolved into the water and a higher pH can be maintained. Color-changing CO2 media is available so that you get a visual indicator when the media is spent and needs replacing.
Use air from outside
The carbon divide content of outside air is 412ppm, but in a busy closed room levels can reach over 1000ppm. A simple fix for your reef aquarium? Bring in the air from outside. In high indoor CO2 levels opening all the doors and windows can help to bring that down, but this isn’t feasible at night or in winter, so run a hose from your skimmer inlet to outside instead. The best way is to drill a hole in the wall or find an existing air vent and stick the pipe through it. Cover the end of the pipe to protect it from rain and insects (a cut plastic bottle filled with floss and carbon will do,) and you have a constant supply of free, lower CO2 air than from inside the house, and the benefit to your tank’s pH will be measurable.
Use macroalgae to scrub CO2
Macroalgae can have so many benefits to reef tanks including using ammonia, nitrate and phosphate as fertilizer, providing a home for mysids and copepods and scrubbing CO2. It does this by using good old photosynthesis – producing oxygen and absorbing CO2 when it is lit up in the daytime – so you can light the algae on a reverse cycle (at night,) or even light it 24/7 so it always photosynthesizes and never reverses or releases CO2. Place some macroalgae in a lit area of your sump, in a macroalgae reactor, or fit an algae scrubber and benefit from nutrient export and high pH.
Add hydroxides
Bicarbonates can buffer KH but they struggle to take pH up to and over 8.2, the sweet spot for hard coral health and growth. Use Calcium Hydroxide, (Kalkwasser,) or a blend of Sodium Hydroxide and Potassium Hydroxide to quickly and easily raise pH to 8.2 and over. Hold pH at over 8.2 over 24 hours and coral growth will become noticeably faster with thicker, stronger skeletons than before. And soft corals don’t mind it either. Note hydroxides are not for beginners or children and are extremely caustic, so store them safely and don’t get them on your skin, eyes, or even your clothing!
Monitor your pH
You won’t be able to record and remedy your tank’s pH without a pH monitor, and better still one with an app that can log and display your tank’s pH in graphical format. Many reef tanks experience low pH due to busy homes or even mass coral respiration at night, and readings as low as pH 7.6 are logged by calibrated pH monitors. Monitor pH throughout the day and night and use the above tools to help you raise and stabilize it permanently.
