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How to Keep Water Clear in Fountains and Ponds

Clear pond

To keep ponds clear, it's best to begin treatment early in the season before problems arise.

All gardeners want to be green — except when it comes to water. Whether you have a fountain, pond or a small reflecting pool, chances are good that at some point you'll have to deal with nuisance algae.

Mother Nature has a way of colonizing just about any watery habitat with algae — even a birdbath. Small amounts of algae may be a simple annoyance, discoloring containers with a film of green slime. In ponds, however, large amounts of algae can clog pumps and filters and harm fish.

The best method for reducing algae growth depends on the size and type of the water feature, the time of year and the extent of the problem, as well as aesthetics and convenience. In general, it's best to begin treatment early in the season — before problems arise.


Here are a few options for keeping water clear:

Barley Straw Extract: Apply this invisible liquid treatment once every two weeks, or as necessary. For best results, apply early in the season before algae is profuse.

Micro Barley Bale: Float the barley straw-filled sachet in the fountain reservoir. Each bale treats 10 gallons for up to six months.

Container Water Gardens and Small Ponds

Small-scale water features can be havens for unchecked algae growth. Here are some easy ways to help keep water clear:

Barley Straw Extract: Apply this invisible liquid treatment once every two weeks, or as necessary. For best results, apply early in the season before algae is profuse.

Mini Barley Bale: Float the barley straw-filled bag in the pond. Each bale treats 500 gallons for up to six months.

Submersible Dispenser: Uses beneficial bacteria and enzymes to clarify water, this discreet dispenser can be submerged in your pond.  Treats 300 to 2,500 gallons for 30 days.

Large Ponds

Ideally, large ponds contain a variety of plant and animal life that can help keep algae in check, but you might need to take steps to prevent murky water. Here are some helpful products:

Barley Ball: This refillable plastic ball treats ponds from 220 to 2,244 gallons; use multiple Barley Balls for larger ponds. Lasts 4 to 6 months.

Aquasphere: Float this biodegradable ball in your pond and it will keep algae in check for 30 days. Two sizes: 50,000 gallons and 225,000 gallons.

Blast: A quick and effective way to deal with algae blooms, which are algae overgrowths that can occur during certain weather conditions. This product is best used along with the Aquasphere for long-lasting protection.

Product Details

Mini and Micro Barley Bales and the Barley Ball use real barley straw and are best used as preventative measures to maintain clear water. As barley straw decomposes, it releases natural substances that inhibit algae growth without harming fish or other wildlife. For the proper type of decomposition to occur, the straw must be in contact with both air and water, so these barley-based products are designed to keep the straw floating on the water surface. The decomposition process takes a few weeks to get going so the effects may not become apparent for two to four weeks. For continuous control add a second barley straw-based product after about four months so it has time to begin decomposing while the first one is still effective.

Barley Straw Extract is a liquid formulation of barley straw that begins working upon application. It comes in an easy-measure container and should be reapplied every two weeks or so. This extract is especially useful for fountains and small water features where you don't want to see a barley-based product floating in the water.

The Submersible Dispenser uses the cleansing power of beneficial bacteria and enzymes to help clarify water. Ideal for small ponds, it treats 300 to 2,500 gallons of water for 30 days. The product consists of a plastic dispenser containing the cleansing formula; refills are available. Because it is submerged in the water, the Submersible Dispenser is another invisible way to achieve clear water.

The Aquasphere is a floating ball made from 100% biodegradable cornstarch that slowly degrades and dissolves. It contains beneficial bacteria and enzymes that reduce excess nutrients that lead to algae blooms. For best results, install a fresh Aquasphere monthly. It comes in a choice of two sizes: 50,000 gallons and 225,000 gallons.

Blast is a concentrated source of beneficial bacteria similar to those found in the Aquasphere. It is best used to manage seasonal spikes in algae growth; use it alongside the Aquasphere for long-term control.

  • For information on designing a water garden, including ways to create a balanced ecosystem that will help prevent algae overgrowth, read Water Gardening: Finding the Site, Choosing Plants and Fish
  • Calculating capacities: A small fountain generally has a reservoir that holds 10 gallons or less. A container garden the size of a half whiskey barrel holds about 30 gallons. To calculate the approximate number of gallons in your pond, start by calculating the cubic feet: multiply length (in feet) x width x average depth. To convert cubic feet to gallons, multiply by 7.5.
  • Barley straw is not harmful to fish and plants; however, straw does consume oxygen as it decays.  If your water feature includes fish, be sure to use the proper product at the recommended rate and consider adding a fountain to help aerate the water.

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