So you thought you didn’t need to worry about winter koi pond algae? Well, think again!
Algae is able to grow both in and under ice. It flourishes until plants begin competing with it for nutrients again in the spring.
Plants use nutrients and compete with algae. They are higher up on the food chain than algae, so they beat them out in the competition.
In my opinion this is possibly THE best reason to have koi pond plants, although there are many other benefits as well.
In fact, it is suggested that plants should cover 70% of the pond’s surface during the growing season.
One way to discourage algae growth in the winter is to have as many plants as you can find that will also grow in the ice. Two of these are pennywort and watercress.
Both fish and tadpoles eat algae. UV lights, algaecides and bentonite are also methods of koi pond algae control. There is no magic bullet.
It may take a combination of all of the above to get your algae under control. UV is expensive and algaecide can upset the balance and even harm or kill your koi.
Both plants and bentonite work with the natural chemistry and ecosystem of your pond.
If you are experiencing bad algae problems one good solution is to go to the grocery store and buy several clumps of watercress (with the roots on), bring it home and throw it in your pond.
And of course pennywort. If you can find it, buy a large bunch and toss it in the pond.
Both watercress and pennywort are readily available, suck up nutrients quickly and help starve both summer and winter koi pond algae!