A Lazy Man's Guide to String Algae Control

The most common problem experienced by pond owners is algae. Of all the technical questions we are asked, questions about algae in the pond are far and away the most common.  

There are two common types of pond algae: 1) the floating single-celled "plankton" algae that results in pea soup pond water (topic for a future newsletter); and 2) string algae which is usually first found in your waterfall or around the pond edges. Unchecked, string algae may take over the majority of your water garden so we will deal with that first. 

You can always treat the symptoms of string algae with algaecides, sweat and elbow grease. But it is much easier on your back (and your wallet) to eliminate the causes now, rather than the symptoms later when the weather warms. 

String algae is really nothing more than an aquatic plant. It thrives on sunlight and excess nutrients in the pond water. Take one or both of these away, and string algae can be controlled:

  • Check your fish load. String algae loves fish waste! You should only have 1" of fish for every 10 gallons of water in your pond.
  • Limit feedings. The less food you give the fish the less, um, "nutrients" they put back into the water.  
  • Use a good number and mix of aquatic plants to absorb excess nutrients from the pond water to starve out the algae.
  • Use floating plants (water lilies, lotus, water lettuce, etc) to shade the water to limit the amount of sunlight entering the pond.
  • Use pond tint to block sunlight, such as PondLogic Nature's Blue or CrystalClear Pond Tint. 

Algae on Waterfalls?

Here's and an easy trick to remove string algae from your waterfall in your pond:

Turn off your pond pump that powers your waterfall. Sprinkle CrystalClear D-Solv on the algae and let it sit for 20-30 minutes. Turn the pond pump on and the string algae should wash off the waterfall into the pond.

You may want to physically remove the algae from the water garden then use a clean-up bacteria such as  CrystalClear Biological Clarifier to eat up any algae that you missed.

Both D-Solv and Biological Clarifer are safe for fish and plants and can be used at the same time with great results. Every water garden or pond owner should have both products.