Ah. Same algae issue.
Barley straw purportedly works by emitting a chemical as it decays which keeps algae from growing. But as you noted, the process then leaves you with a rotten bale of straw. Which doesn't appear to be working anyway, if I'm not mistaken. Some people swear by the barley straw extract - same idea, but no rotting bale of straw.
However, let's approach this problem another way - consider the algae not as THE problem, but only a symptom of the ACTUAL problem. You have an excess of organic material in your pond - too many fish, too much fish waste, excess food, rotting plant material, etc. The algae is not only letting you know you have an imbalance, it's also helping to keep your pond water safe for your fish by consuming the excess. By treating the symptom, you are not getting at the root cause.
You said this was a 400 gallon tank, correct? How many fish do you have? What kind? How big? How long has this pond been running? What type of filtration? Do you have aeration? A How many plants? Do you test your water? If so, what are the results?