The Case of Koi Pond Algae
If your otherwise-pristine koi pond suddenly develops the appearance of a green shag carpeting, you are witnessing the affects of an algal bloom. While common in koi ponds, this natural occurrence is highly unsightly and can even be harmful with excessive growth. Koi pond algae is normal but needs to be kept in check. Here’s a guide to keeping your waters crystal clear!
Like anything in life, balance is key. Algae is fine in small amounts, but when you get too much, it becomes a problem. Algae is a normal function of a koi pond. Though it can be unsightly at the surface, it is normal to have some algae on the sides of the pond or even on the bottom. This algae can actually benefit the pond by keeping nitrate and other nutrient levels in check. Algae can also become a snack for koi fish. And in small amounts, algae can actually add oxygen into the pond water through photosynthesis.
Season of the Green
It is normal for some algae to appear in spring, though summer is the true season of the algae. Sometimes it can seem to appear in the pond out of nowhere. This is called an algal bloom and is caused by direct sunlight, warm weather, and fish waste. Other factors include decaying organic material, such as an animal carcass, or chemical overflow from a neighbor’s fertilizer. High concentrations of nutrients in the water combined with insufficient filtration, a too-high pH level, and a possibility of standing water can cause algal blooms in any koi pond.
No matter the cause, when excessive algae appears in your koi pond, oxygen levels drop rapidly.This is a problem because a) your koi need oxygenated pond water and b) the hot summertime algae season is also a time of the year when koi need more oxygen to breathe.
Preventative steps may be taken to avoid algal blooms. First, provide shade for your pond. Strong and direct sunlight can aid algal blooms. Add foliage, pond plants, or consider building a pergola. Proper filtration will also reduce your risk of an algal bloom. Perform regular maintenance checks and ensure that there is no standing water in the pond – standing water increases the chances of algae buildup. If you believe your water is not circulating, consider adding a fountain or a waterfall. This will promote both aeration and movement within the pond water.
Because algae grows more rapidly in warmer water, consider adding depth to your pond. A deeper pond will remain cooler in the warm and sunny months and will accumulate less algae. And keep careful watch of the pH levels in the pond. Algae favors higher pH levels. Another way to prevent algae blooms is with a partial water change. Drain off a tenth of the pond water and add the new water slowly to prevent a shock in the koi.
As a last resort, turn to algicides. These are chemical products sold in the U.S. and registered under the Environmental Protection Agency, though improper usage could kill off your pond plants and possibly some koi.
Do you have koi pond algae? How do you take care of it? Let us know! Leave a comment or write to us via the contact form!