Algae and Your Koi Fish Pond  

Got Algae? Here’s what you need to know about algae in your koi pond, how to prevent it and how to get rid of it.

Algae has been around for 2 billion years, and there are 30,000 different varieties. It can live through just about anything thrown at them. So by all accounts, it’s not going anywhere soon. Doesn’t mean you have to like it though. Or that you have to live with it.

Next to parasites and bacteria, algae is probably the most despised substance in a koi hobbyists pond. Going to bed with a clear pond and great water parameters only to wake up to an algae bloom is incredibly frustrating.

Even though it reduces visibility, making it more difficult to see your living jewels, and turning your water green algae does have its benefits. The dreaded Spring Bloom can be helpful. It is Nature’s way of providing balance and acts as an excess nitrogen filter when your filtration system is not fully up to speed as temperatures start to rise.

In ponds, especially newer ones, algae is usually just something that the owner will have to grin and bear. Once the pond has had a chance to cycle and the bacterial colonies that you have set up establish themselves, they will begin to regulate the ammonia cycle in the pond.

What is Feeding Your Algae?

Excessive algae is an indicator that something in your pond is out of balance. Essentially, algae lives off of excess waste products (their source of nutrients), sunlight and low oxygen concentrations.

Nitrogen and Phosphorus

Your algae love this stuff. So as your levels of nitrite and nitrate start to escalate from waste or decaying organic material, so does the likelihood that you will have heavier algae growth. Phosphates are usually introduced in any fertilizer runoff coming into your pond. A good testing kit is essential for any pond keeper. Use it to keep an eye on nitrite and nitrate levels.

Sunlight

Algae relies on photosynthesis to survive. The biggest provider of that source is the big yellow ball in the sky. More sunlight, more to live off.

Inadequate Oxygenation

Lower dissolved oxygen in the water means that as the algae dies there is not enough of it to break down the decaying matter and so that dying algae then becomes the medium for more algae growth. Low oxygen is also a source of stress for your koi, which increases the risk for illness and disease.

Temperature

Algae thrives in warmer water. It will outgrow the aquatic plants you have in your pond at lower Spring temperatures, but it will really take over in warmer waters.

Overstocking

Too many fish means too much waste. If your fish load is higher than your filtration can take, it will lead to poor water quality as well as all the nitrogen a growing algae needs.

Poor Filtration

If you aren’t providing adequate filtration, your water quality will suffer and the excess nutrients left behind can contribute to algae growth as it has something to feed off.

Overfeeding

Regulating the amount that you feed your koi can prove helpful in the event of an algae outbreak. Removing anything that it can use to sustain itself is a good way of minimizing the time it’s in your pond.

Rain Water Runoff

If your pond is in a low lying area and rain runoff makes its way into your pond, it can carry a lot of organic matter, fertilizer phosphates and debris that will feed the algae.

Pond Construction Material

Some materials used to build your pond will have a natural higher pH than others. A higher pH makes the assimilation of particular nutrients easier. So materials like concrete, limestone and marble when used in a pond’s construction can be a factor  in algae growth, too.

Types of Algae

The two types of algae most commonly found in koi pond are filamentous algae and phytoplanktonic single cell algae.

Phytoplanktonic Algae

This is the single cell algae responsible for a healthy pond (or any body of water). But in large numbers, it is also responsible for the green water or pea soup that can be incredibly frustrating for koi pond enthusiasts who actually want to be able to see their koi swimming around.

 

Filamentous Algae

This is the hair or string algae that forms clumps on your pond’s surface. It begins life on the bottom of your pond and then breaks off to float to the surface, giving that green carpet look that all koi enthusiasts can absolutely do without.

How to Treat Algae

Get rid of the nitrogen and the sun and you get rid of the algae. Simple to say, but not as simple to get right. Whether chemical or natural, old salts at algae control will have their time-worn techniques—like using a toilet brush to remove string algae. It is mostly trial and error based. And it will probably be the same for most enthusiasts. Find what works for you.

Shade

Providing shade is essential to keeping algae in check. It stops direct sunlight and your algae’s photosynthetic ability to create food. If your pond isn’t in a shaded area, enthusiasts use anything from large deck umbrellas and awnings to trellises with leafy or flowering plants in stopping the sunshine from pouring in.

Plant life

• Trees

As stated, shade is helpful in regulating algae’s ability to grow. Trees are natural shaders. They also help to keep the water temperatures down. And they provide a little relief to the landscape, too.

• Surface water plant

They are a great natural shader and will also provide some cover from the prying eyes of aerial predators, too. Larger leafed plants are usually better nitrogen feeders as a rule.

• Submerged water plants

Oxygenators, like Anacharis and Cabomba will pull double duty by providing oxygen (for the koi and those aerobic bacteria) while syphoning off those nutrients that algae thrive on.

UV Sterilizers

This is effective against the floating phytoplanktronic variety of algae (and some undesirable bacteria, too). As it passes through the filter, the single cell algae is eradicated. It is advisable to wait to use the UV sterilizer until your beneficial bacteria is back to normal levels as UV will also eradicate this bacteria.

Skimmer

Removing the floating material before it has a chance to sink will lessen the chance of it decaying, thereby changing the water quality parameters and becoming a source of nutrition for algae. In the event of of an string algae bloom, clean your skimmer often as it will become clogged very quickly

Adequate Aeration

Algae don’t do as well in higher oxygen concentrations. Especially if that well-oxygenated water is also moving. Putting in a waterfall, fountain or another aerator can help to boost oxygen levels by giving the beneficial bacteria that rely on it to break down organic waste a little more ammunition in that fight against dead algae.

Lighten Up on Feedings

You don’t want to add to your nitrogen load, so reducing the amount of food that can end up on the bottom is helpful. The good news is, hungry koi will eat string algae. It is not nutritious however, so don’t rely on it to sustain your koi.

Barley Straw

This natural straw decomposes and introduces a similar chemical released by a dead algae cell that will kill other algae cells around it once—just in higher concentrations. It can take up to a month for the full effect to be noticed so it is a little longer than some other substances, making it a frustrating option for many koi enthusiasts.

Hydrogen Peroxide

Hydrogen peroxide is a quick fix solution to algae growth that has its supporters and detractors. It has a quick response to algae and usually kills off smaller blooms quickly. It is available in different solution strengths, some of which can be harmful to you and your koi. One thing to be aware of though, is that as it kills algae, that dead algae will start to suck oxygen out of the water. Adding aeration and physically removing the dead algae is important.

Koi Clay

Koi clay (calcium bentonite), as well as adding minerals and absorbing toxins, has helped to control string algae. There are lots of theories as to why—from creating healthier bio systems in the water and the koi’s digestions to smothering the algae—but the mineral-rich clay has many vocal supporters who actively use it to control string algae. It will cloud your pond water. So be prepared for that for a few days as it settles.

Vacuum

Getting rid of algae might require a little more elbow grease on your behalf. Especially with string algae. A good pond vacuum used to remove build up of dead algae will stop it from soaking up oxygen and providing nutrients for live algae. It will also reduce the stress on your skimmer. You might want to consider adding some beneficial bacteria after a vacuuming.

Algaecides

There are more than a few of them available on the market, and enough that it could be an article all its own. Koi keepers or pond enthusiasts that use algaecides (either as a preventative or curative measure) have their old faithfuls. There are many sites that will promote one brand over another, but it comes down to what works best, in the shortest amount of time for the individual using it.

Algae-eating fish and snails

Some enthusiasts introduce algae-eating pond mates like Tilapia. However, most varieties of algae eaters aren’t hardy enough to survive the winter. Additionally, they can be harmful to your koi (plecos can suck the slime coat—and sometimes scales—off of koi if there is no algae available). And unless you have Snailzilla, snails won’t make a dent in blooms.

Keeping koi can be a real labor of love. But enjoying the many joys that healthy koi in a pristine pond brings is tough to beat. We at Next Day Koi are ready to help keep that pond beautiful with koi fish for sale from some of the industry’s top sources. Contact us to order your next living jewel. Join us on Facebook or our sign up to receive our emails to stay up to date on all of our great offers.