Raising the pH of baking soda

One of my obsessions is marine aquaria (aka salt water aquariums). Water chemistry is absolutely vital in having a successful aquarium, especially when it comes to corals and invertebrates.

Some of the more vital parameters in marine aquaria are pH, Calcium, Alkalinity, and Magnesium. All are interrelated.

pH is, as we know, the level of acidity in the water. Alkalinity is a buffer for pH, it's also a way for aquarists to measure bicarbonate (which corals use to grow). Calcium is another growth source for corals and forms ions with carbonates and bicarbonates, Magnesium allows for more saturation of calcium in the tank before the calcium precipitates out of the solution and helps control the use of calcium. Magnesium could probably be used in pools to help prevent scaling caused by calcium, but the general consensus is to avoid adding metals to your pools. We keep our calcium levels at 450 to 500 ppm in our aquariums. Natural seawater is about 420 ppm.

Anyway, we use baking soda on a small scale to adjust alkalinity. We typically adjust alkalinity and calcium simultaneously. Normal pH of seawater is 8.4, so for tanks with normal or low pH we will actually bake our baking soda for an hour or so at 300 degrees in order to raise the pH of the baking soda. Then, rather than having a slight lowering affect on pH, it will actually slightly raise it when added to our tanks in a solution.

After being baked for an hour, raising the alkalinity by 25 ppm will increase pH by about .3 units.

Unbaked baking soda has the following affect: raising alkalinity by 25 ppm will decrease pH by about .04 units.

Not that there's a large affect on anything, thought it may be handy info for someone. This way you can somewhat control the affect on pH when adding baking soda.

Most of this info was snagged from an article by Randy Holmes-Farley, a well known chemist and author in the marine aquaria trade.

Interesting. And, I learned a new word --- aquarists. Never heard that before.

:)

I think we "aquarists" may have invented that.