Problem
The anode on your aquabike has deteriorated (part under the frame).
Origin
This problem may be due to improper water treatment or normal wear of the part.
Resolution
The appearance of whitish marks on the anode is perfectly normal (part under the frame).
Anode is used to protect an aquabike from corrosion. This part corrodes instead of the aquabike, especially when the water is treated with salt. As it oxidizes, it gradually destroys itself by forming a friable film.
If the anode is worn, you should replace it. Please fill out the form (available here).