Algae is growing ON my barley straw. What’s wrong?

If there is algae growing ON your barley straw, something is amiss.

Barley straw is added to ponds to retard the growth of algae.  So, it definitely should not be growing ON the barley straw.  What gives?

I get a few of these inquiries each spring. Barley straw that is well colonized by beneficial bacteria will greatly retard the growth of algae in the water surrounding the straw and there should be no algae growing on the straw itself.  If there is, something is definitely out of whack.

What can cause this failure?

The number one reason for this in the spring time is that the water has just warmed to the 40 to 45 degrees range, warm enough for the algae to start growing but not warm enough for the bacteria to develop sufficiently to block growth.  This problem will take care of itself once the water temperatures stabilize over 50 degrees.  So, patience here is the best cure.

The second most common reason is that the water does not have enough carbonate to support a thriving population of the beneficial bacteria.  The water is too ‘soft’.   This is a common problem on the East Coast and up in mountainous regions.  This is easy to check for and easy to fix.  If you suspect this is the problem, test your pond water for ‘Total Alkalinity’ using our Microbe-lift 5 in 1 Test Kits. If the level is below 100 mg/l, supplemental total alkalinity is needed.  See my blog on correcting Total Alkalinity if this is the issue.

The third most common reason in small backyard ponds is that the water has been allowed to concentrate nitrate to such a degree that no amount barley straw will work.  To check this, use either our Microbe-lift 5 in 1 Test Kit or our Microbe-lift Nitrate Test Kit. Test in the morning and afternoon over a period of several days. If your levels are consistently over 5 mg/l, you really need to lower your nitrate level.  This can most easily be done by doing one or more water changes.

The last possibility is that the pond has been dosed with chemicals that have killed off the beneficial bacteria which need to colonize the straw (as well as your bio filter).  Review your pond management practices and stop using chemicals.