1: Looking at an anode and saying "yup not corroded" is not how you check such things.

2: If they actually wanted to check it, there are several methods, they did none of them. They include: Weighing it, killing the algae and seeing if the power output changes, trying other metals for the anodes, trying other plants instead of algae in the water.

3: If you put salt water between two anodes you will get electricity. Period. If they claim this didn't happen, and "the algae did it", you're going to have to posit some method for the algae to prevent this, while substituting their own electricity. This will require new chemistry.

4: Algae are non-polar, so I don't see how they can direct the positive and negative current toward the proper anode to make electricity.