Getting a Jump Start on Algae this Spring

By Nanette Winowiecki, Pond Place, Inc., Milford, MI Originaly published in Passion For Water, Spring 2009, Revised Spring 2014

Algae can be one of the most frustrating parts of maintaining a pond. However, by taking proactive steps in the spring to head off algae growth you can begin to spend more time enjoying the natural beauty of your pond and less time maintaining it.

Getting a Jump Start on Algae this Spring

For those of you new to ponding, there are two common types of algae you're most likely to encounter:

String Algae are fibrous green strands of algae that can grow out of control if not kept in check. Excessive growth of the string algae removes the oxygen that fish need from the pond water.

Green Water Algae Bloom are tiny algae spores that will cause your pond water to turn green and cloudy. This is part of a natural cycle caused by an excess of certain trace minerals, nutrients and sunlight.

The first step in heading off algae is to properly clean your pond each spring. The debris on the bottom of the pond should be physically pulled out or removed with a pond vacuum. Follow this with a 50% water change. Prior to refilling the pond with new water be sure to add EasyPro Water Conditioner to remove chlorine and chloramines, detoxify heavy metals and reduce fish stress.

If you have heavy debris and fish waste on the bottom, over 1", it may be easiest to completely drain the pond to remove the debris. Prior to completely draining the pond be sure to set up a fish holding tank with water from the pond and place in the shade, use an EasyPro Aerator to add oxygen to the water while the fish are in storage and be sure to cover the containers so that the fish cannot jump out and predators cannot access the fish. Be sure to add the EasyPro Water Conditioner prior to reintroducing the fish and float the fish in a bag to equalize the temperature if the difference in temperature between the holding tank and the new pond water is more than 2°F.

After cleaning the pond water reconnect the pump and filter.


Minimize string algae growth:

  • Use an algaecide to kill off the string algae you were not able to physically remove. A liquid algaecide, such as AlgaeFix, is good for treating algae in the pond. When treating algae on waterfall or stream rocks it is recommended that you turn off the pump, place an aerator in the pond to provide oxygen for the fish, sprinkle a granular algaecide, such as GreenClean on the rocks and let it set 30 to 60 minutes. Turn your pump back on and have a clean net ready to catch the algae running into your skimmer.
  • Regularly test the water using Pond Care Master Liquid Test Kit for the pH and a Pond Care Liquid Phosphate Test Kit to test the phosphorus content of the pond water. High pH and phosphorus are the leading causes of string algae. If the pH is high, use EasyPro pH Down as needed.
  • If Phosphorus content is high, use a phosphate remover as needed.

Minimize green water algae blooms:

  • Check for high nitrate levels, which can cause green water algae, using a PondCare Nitrate Test Kit. If the level of nitrate is high a 25% water change should be performed.
  • Add plants to your pond to deprive the algae of light and nutrients. To do this effectively, plants should cover a minimum of 66% of the water surface if the pond is in full sun. Generally, if you have the proper water plant level and the nitrates are in the correct range, the green water algae will clear naturally in a week or two, provided you are adding bacteria to your pond on a regular basis.
  • If your pond is in full sun or you find that you are plagued by green water algae all summer we highly recommend installing an EasyPro Ultraviolet (UV) Light Clarifier to your pond system to clear the green water algae. We find the UV Light is the best option to keep your pond water crystal clear throughout the summer. The purchase of a UV light does require an up front investment, but in the long run it is cheaper than the chemical approach and requires minimal labor once installed.

In addition to the actions above, EasyPro water treatments are great for improving the overall biological balance in ponds.

  • Establish a good biological balance in your pond by adding EasyPro All-Season Pond Bacteria on a regular basis.
  • Use EasyPro Sludge Removing Bacteria to breakdown the remaining organic matter from dead algae on a regular basis. EasyPro Sludge Removing Bacteria is pre-dosed in individual water soluble packets.
  • Some pond owners add EasyPro Liquid Barley Extract on a regular basis to keep their pond clean and clear. EasyPro Liquid Barley Extract starts working immediately and is easier to use than the barley bales or barley pellets. We have found it works better to cut the monthly dose in half and add weekly as opposed to monthly.

By following these simple maintenance steps on a regular basis, you will significantly clear your pond and be able to spend more time relaxing and enjoying the beauty and sound of your pond all summer long.

View Featured Products