Koi Pond Algae
Koi pond owners often have to fight algae problems in their ponds
and while there are a variety of ways one might treat algae, extra care
needs to given to those that have fish of any kind including koi fish.
One thing that needs to be kept in mind is any pond that contains
fish, must have some form of filtration, and ideally biological
filtration, in adequate capacity to help deal with the waste that the
fish create. Many water quality problems can come up if a pond is under
filtered, or if too many fish end up in the pond for it's size and
It could be said, and most experts agree, that high fish loads end up creating koi pond algae
or algae in any small fish pond more than anything else. Fish, and
particularly koi, can eat a lot, and they can create a lot of waste. The
more fish you have in a pond, and the larger they are, the more
influence they might have.
So the first rule is to make sure you don't have too many fish in a pond for it's size. We have a simple fish load calculator you can use to determine if your pond is overstocked.
If you do find your fish are overloaded it would be best to find
another home for some of them and to lessen the load on the pond. Many
times when this is done, a pond can return to a fairly good condition
without much more being done.
Fish, of course, need to eat, but it's best to not overfeed them.
Uneaten food can sink to the bottom and raise nutrients in the water as
the food breaks down. Ideally you might want to only feed your fish
once per day, and no more than they can eat in about five to ten
minutes. If you ever see much food going to waste, back off a bit on the
feeding amount. You might also want to look for a floating fish food
which will give them more time to eat without wasting any food on the
It's also not a bad idea to add beneficial bacteria for small
ponds from time to time, first to help prime up a biological filter, if
one is in place, and secondly to help get some active bacteria working
in the pond body itself. This can help lower nutrients like phosphates
and nitrates that algae might feed on to grow.
If the pond get's a lot of sun exposure it's also useful to add
surface or floating plants to help provide some shading, however some
koi love to eat plants and may damage them if they are not protected.
One useful tool for this is to put plants in floating islands which also
provide shading but protect the plants as well.
By taking some of the simple steps noted above, many pond owners
have helped to clear their ponds of algae and they've done it safely and
without the use of harsh chemicals.