It is rarely mentioned when discussing algae control, but pH levels can really put a damper on your tank as a whole. The role algae play in the water is really related to an excess in most cases, typically phosphate, ammonia, or nitrate. Algae can really flourish in water where there are plenty of organic organisms present, so they have an ample supply of food. The threat algae pose can be detrimental to the life in your planted tank, as they directly affect the pH in your water. Algae’s Favorite pH You will find that algae can exist in a wide range of environments and even survive the harshest of conditions, but they have a happy zone where they will grow until capacity allows. Algae in these waters will thrive and can most certainly outcompete even the hungriest of plants. Algal growth rates are limited when pH levels are Neutral or lower. Like plants, Algae undergo photosynthesis using light for food in order to grow. Algae also prefers warmer water where they can rapidly multiply. Cooler temperatures slow the growth rate. Your Plant’s Daytime is controlled by pH When do plants like to eat? Hmm, could it be during the day when light is present? Ding ding ding! We have a winner. During the day plants photosynthesize, uptaking CO2 in the water in combination with light energy, the produce food. As CO2 is drawn from the water, the pH increases. This creates competition in the water for plants and potential algae. Algae will deplete the water of inorganic carbon and will raise pH levels, thus further promoting stronger algal growths. If the pH gets too high (10+) then ammonia can ionize, and that is lethal to your aquatic life. This competition forces plants to work harder to uptake nutrients before algae gobble it all up. Suffocating Sleep Means Blame the pH Once lights go off, photosynthesis also is halted, so plants and algae quit soaking CO2 and begin the respiratory phase. It is during this time algae start feeding on the oxygen from photosynthesis. During this, algae give off CO2, which adds to the CO2 production at night. This elevation in CO2 forces the pH to significantly drop, and algae being to fight fish for oxygen. How Algae piggybacks on pH If you’ve followed along so far, then you can see that algae force the pH to fluctuate during both the day and night. When the pH shifts like this, it can cause unwanted stress to your livestock (potentially killing them) and can slow growth rates down in the tank. The more algae present the larger the impact on pH levels algae will have. By adding a few fast-growers, you can help your tank outcompete algae for nutrients, keeping your tank nice and clean. Do not let algae have free rides on your pH levels. The fact remains algae is an ongoing battle and even to this day, people are still running into issues. Getting a properly balanced tank can be very hard to get right, it can take a few tries, but not giving up, and sticking to the grind will yield fruitful results and satisfying gratitude. Think we missed the mark on a certain part or want to add some value with your opinion or researched facts, feel free to contribute. We only grow together, if we learn together. Share your knowledge, so others can spread your intellectual wealth. We appreciate it!