The most common cause of a goiter is lack of iodine, ...Even with the right amount of iodine, the thyroid gland can swell, creating a goiter. This can occur in any type of thyroid disease, including hyperthyroidism, hypothyroidism, thyroiditis, and thyroid cancer.
Shock treatment powder bags. Skim off whatever algae you can from the pool using a pool skimmer. Scrub the inside edges and walls of the pool with an algae brush to dislodge stuck algae. Purchase sufficient amounts of algaecide, as noted in the instructions on the bag, that match the total gallons of water in the pool.
The supplies you will need to handle black algae spots: a stiff pool brush, chlorine tablets and algaecide. These directions are not for a vinyl lined pool. Do not swim in your pool during the black algae spot treatment. Each black algae spot needs to be brushed with your stiff brush.