Floating Algae Problem

[Nokoff]

I have this algae lurking in my pond and I'm not sure how to get rid of it, the water is otherwise clear.

Please HELP! I've attached a picture for descriptive purposes

[MikeM]

This is typical of watergardens in summer heat, heavy sun and minimal filtration. It will go away with the change in seasons.

Describe your pond, filtration, weekly maintenance routine, and water parameters & folks may be able to give targeted advice.

[Nokoff]

Quote: Originally Posted by MikeM This is typical of watergardens in summer heat, heavy sun and minimal filtration. It will go away with the change in seasons. Describe your pond, filtration, weekly maintenance routine, and water parameters & folks may be able to give targeted advice.

The pond is an oval, 1,5 m deep in the center and shallows towards the sides. Roughly 6000 liters it is running on a sand filter, ultrazap and bio ball filter. The filter runs 24/7... I'm not sure what other information I can supply as I don't have a test kit for the pond

[CarolinaGirl]

It's really very difficult to assess what a problem might be without knowing the water chemistry. You will need to get yourself a good test kit or at the very least, take a water sample to a pond store so they can test it. Algae needs nutrients to thrive, so you need to determine where it's getting it's nutrients. Excess koi food, excess fish poop (caused by too many fish), build-up of crud in the pond bottom, and improper filtration are all likely contributors. Sand filters are typically not very good for water gardens. Sand filters were designed to filter chemically clean water (swimming pools) and simply cannot handle a large load. The sand clogs up and develops channels through it which allows the water to pass with no filtration. Most people who have sand filters have to back-wash them at least once a day, sometimes even more!

[S. Stone]

My own experience with sand filters: I just (last weekend) got rid of my 2 oversized Hayward sand filters that have been a part of my pond since I began pond-keeping in 1997. Lately, the top layer of sand in each of the sand filters would get coated with a solid sheet of the same green algae that covers the entire concrete surface of the pond, itself –fine in the pond, but not the filter. On a weekly basis, I had to pull off the multi-port valve on top and physically scrape out the sheets of algae. (The pressure would keep building and building and, one time, two of the elements at the bottom actually broke off, letting all that cruddy sand go back into the pond.). I now have two Aquabead filters, in addition to three 250 gallon up-flow filters, which are strictly for bio-filtration. So far, after only 3 days with the Aquabeads, the water quality "looks" much better and the fish seem to be much more comfortable.

You mention bio balls in a sand filter. I tried that at one time, too, and wound up with a huge, stinking, anaerobic mess. It MIGHT be all right, if you have a blower on the filter and use it on a regular basis to break up the sticky pack of the bio balls. I didn’t, and it wound up costing the lives of several nice fish, in spite of my best efforts at maintenance.

[MikeM]

In your situation the algae can be limited if the waterlillies are thriving with leaves covering 70% of the pond surface. Without that sun blockage, need to limit nutrient in the water, have solid biological filtration and regular water changes. Limiting nutrient means not fertilizing the plants and having low fish population (small fish only) which is fed sparingly. Goldfish are better than koi in these circumstances. The filtration should turn over the volume of the pond at least once every two hours. For your approximate 1500 gallon pond, that means 750 gallons per hour ...hourly turnover is better. For water changes, 10% per week is the minimum typically recommended. Personally, I believe 20% per week is minimal.

If you are wanting to raise koi other than as annual fish that die over winter or in the spring, see if your local library has Koi Kichi. (A dozen years old, but still the best.) Read it.

If your goal is a pretty watergarden with some fish, get goldfish and grin & bear the algae bloom for a couple of months each year. Fertilize the soil with tree spikes and you'll get the lillies growing like mad. Enjoy the blooms. The fragrance of tropical lillies can be intoxicating. ...but don't expect koi to thrive.

Whatever your goal, I wish you the best. Nothing like water in the garden to make the world seem at peace.