Barley bail

I have used something in my pond once or twice that was a sheet of hay in like mesh to keep it together. Supposedly it was suppose to keep the pond clean, it did pretty well I guess. Is this what is called a "barley bail"? How does it keep the pond clean? Just curious.
 
Some people will tell you barley doesn't work; others swear by it. I've used it with success. Without reading the references above, I seem to remember that it outcompetes algae for the nutrients it needs, thus keeping the water clear of algae. I've bought mine from thatpetplace or Foster & Smith, one small bale lasted all summer in 300 gallons. I'm sure by now PetSmart is carrying it in their pond section.
j
 
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