In Short ocean acidification is the caused by increased atmospheric CO2 levels increasing ocean CO2 levels causing a drop in pH. But why is this such a problem?
Alright so the big and main problem is coral health. Coral skeleton is made of calcium carbonate which at a pH of 7.0 or less starts to dissolve, coral growth stops at a pH of 7.8 or less. To give you some general idea the ocean should be around a pH of 8.4 and that’s where coral thrives. Coral is the backbone obviously to coral reefs which are home to a huge diversity of species and even if a species doesn’t live on the reef it almost certainly depends on it in some way because all parts of the ocean are connected. For example many organisms such as blue green chromis, trapeze crabs or yellow clown gobies live in acropora corals and without those would be more exposed to other natural threats. Other species that rely on shellfish for food would begin to fade out or forced to compete with the remaining limited recourses. This huge loss in biodiversity would also have economic impacts on people who rely on fish or shellfish farming for a living, tourism for cities with natural reefs would also decline. Certain species of plankton that help with carbon sequestration and oxygen production may also start to decline, and 80% of the world’s oxygen comes from plankton so we need those little suckers. Cyanobacteria also thrives in the high CO2 low pH environment with is toxic to all life on earth.
Because ocean acidification is caused by high atmospheric CO2 levels the only way to slow it down or reverse it is to lower our CO2 emissions and let phytoplankton do its thing. This can include things such as more sustainable energy such as solar or nuclear to power not only our daily lives but commercial entities as well such as cargo ships or planes. Better battery technology, more environmental friendly phytoplankton fuel or heck maybe even finally cracking fusion would help. Not much we can do on the small scale, mostly large companies who need monetary incentives to act upon. However small acts like driving a Tesla can make a little bit of difference, plus Tesla drivers are the coolest people around.
So that’s all great and all but how does this affect us as hobbyist on our small scale reefs in our homes? Well it turns out us oxygen breathing, CO2 excelling people living in the same walls as our reef doesn’t mix well. Our homes often have higher CO2 levels that normal atmosphere. They aren’t high enough to harm us however this among other reasons can make it challenging to keep our pH levels high enough in our reefs for proper coral growth. Lucky there’s a few tricks we have.
Probably the most common used method is the chemical route. Alkalinity is a pH buffer, this is why alk can drop quickly in heavily feed tank even without much coral growth. And thus simply dosing a little extra for alk or kepping your alk levels a little high can increase your pH and along with prevent it from swinging to much. Kalcwasser while not as popular in this day and age as it used to be also convert CO2 into alkalinity which can have a much more direct and impactful difference on your pH by hitting it on two fronts.