I think you should repost this as a new post, theres a pretty sharpe water quality guy I've seen on this board but he may not see add-ons to old posts. Algae needs sunlight to grow, so I dont think its growing in your well, but it might be an indiction of higher than normal nitrates in the groundwater, you also may have higher than normal sulphur in the water. High nitrates may be caused by inefficient septic fields or they are too close to your well. I defininately think you need to have the water tested by a local professional firm and get some advice from them or your local public health department about maybe a filtration system.