The barleystraw minibale that has been in your pond for 6 months now should be removed from the pond before it decomposes any further in the water. If this is allowed to rot down in the pond it will create additional nutrient in the pond water that will feed the next ‘wave’ of algae production.
The fresh one that you added last month should be activated by now and ready to continue the good work of keeping the algae and greenwater at bay. The barleystraw acts as an inhibitor to the growth of the algae and a minibale will continue to work over a 5-6 month period.
It should float in the water and be allowed to move in the wind or be tied into a position where it is constantly being moved by a waterfall or by the flow of water from a pump or a filter box.