PH Swings

PH can be a difficult factor to control in our tanks, especially when we want to lower that value safely for our inhabitants. There are a number of things that can affect the stability of our PH. KH, our buffering anions, when kept at low values for shrimp such as Crystal Red shrimp can allow PH to fluctuate wildly.

Common Causes

Probably the number one cause of unexpected PH swings in your tank is due to the addition of an object that is leeching mineral content into the water. This can come in the form of a rock that is slowly dissolving solids into the water stream. Dead coral and other forms of live rock will also release dissolved solids into the water. When an object like this is introduced into our tank, it will slowly affect the KH and or GH of our water which in turn often raises the PH. It is very important to test each rock you plan on introducing to your tank. Simply pouring vinegar on the rock’s surface and seeing if it bubbles will tell you whether the rock is likely to dissolve in your tank. A rock that bubbles on contact with the vinegar will definitely not be suitable for your aquarium. Other potential things to be wary of when selecting a rock are whether it has any obvious streaks of metallic or shiny surfaces, this can be a sign of potentially toxic substances in our tank.

Driftwood is another common source of PH swings in our tank. Wood releases tannic acid as it decays. This will forcibly lower the PH in our tank if it is introduced in sufficient quantity. Soft woods are generally not recommended since they decay much quicker and can often have other acidic or toxic chemicals in their sap which can be harmful to your tank. When selecting a piece of driftwood look for hardwood that has no visible signs of decay. It should be cleaned of all bark and particulate matter, then cured by some means. You can find more about curing wood for your aquarium here.

Plants can also affect your PH. During the day plants use photosynthesis to convert sunlight and carbon dioxide into energy for the plant. At night plants shift to respiration, similar to animals, absorbing oxygen rather than carbon dioxide. This shift can have a severe effect on PH if your tank is densely planted. If you plan on having many plants in your aquarium you can offset the effect this has on your PH by introducing a bubble maker or airhead attached to an air pump. This will ensure that your water is constantly being oxygenated to offset the effect the plants can have.

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