Barley Straw - controlling pond algae

So let me give you the real deal on controlling algae or green water in your pond using barley straw. Lots of websites would love to sell you this material (at some incredible prices) so here's how you can make best use of this product.

Understand that it does work. But that you have to follow directions very closely or you'll not only waste your money but add to the problem by adding more gunk into your pond.

What are You Controlling

The problem is in the floating algae - the blue-green algae that clouds up the pond water. And barley straw does a nice job on this but it doesn't take care of string algae very well nor the algae on the sides of the pond (you want algae on the side of the pond - it's a good algae).

It is the chemicals exuded from the decomposing barley straw that inhibit algae growth

Water Temperature

Water temperature plays a huge role in controlling algae. If the water temps are 50F (early in the spring) then the barley will take up to 6-8 weeks to begin emitting enough decomposition chemicals to control algae. This is not a spring remedy for green water.

At water temperatures of 68F (summer temps) then the barley straw starts working in a week.

Once the straw starts working, it should continue to work for 4-6 months depending on water temperatures. (higher temperatures decompose the straw faster so it works for a shorter time)

How Much To Add

You require 0.8 ounces of barley straw per 10 square feet of surface area of your pond.  Given that recommendations vary depending on a range of environmental conditions, you're safe using 1 ounce of barley straw for every 10 square feet of water surface.

So calculate the square foot coverage of your pond.  A typical pond 10 X 11 foot pond gives us 110 square feet of surface.    

But we have to divide that square footage of 110 by 10 (remember the first paragraph of .8 to 1. ounces per 10 square feet)  and that gives us the number 11

Multiply the 11 by 1 and you have 11 ounces of barley straw for this size of pond.

Translate that into pounds (16 ounces/pound) and you have about 3/4 of a pound of straw for this sized pond.

Not Too Much

Do Not Exceed 3.3 ounces per 10 square feet! This excess amount of rotting vegetation takes up oxygen and your fish will start struggling as will the rest of your pond’s ecology. Too much is not a good idea and more isn't better in this case.

How to Apply It

This is important information and if you decide not to do it this way, you'll only increase your problems.

The straw must be put into the pond so that water can reach every bit of the straw. Full bales must be broken up and bagged into some bag like nylon mesh that holds it into one place. Pond suppliers often ship the straw in net bags and these are acceptable "as is".

If you don't bag it, you'll discover that rotting straw is not a nice thing to clean out one strand at a time.

Do not let the straw sink below 3 feet in the water. Important!

Once barley straw gets below that depth, research has shown it loses its effectiveness. Oxygen in the upper levels of the pond are higher and these keep the straw effective. Water currents are also higher in upper levels and these will move the secreted chemical around the pond (circulation is not a problem if you have a pump working).

Excess sediment on the pond bottom will slow down or stop the barley straw from working so do not allow the barley to sit on the bottom of even shallow ponds. Suspend the sack from a float or for a more natural look - put the float into the straw net sack with the straw.

This will cause the straw to float to the surface. It is then easy to set up an anchor to set the floating sack at the right level and it is out of eyesight at the same time.

If you have a choice of where to put the barley straw, put it in the center of your pond or where the pump water flow will carry the secreted chemicals to all parts of your pond.

Sources for Products Mentioned on This Page

Multiple sources for barley straw in small quantities and in liquid form

Doug's Ebooks on All Aspects of Gardening

All of Doug's EBooks Can Be Found Here