High alkaline swimming pool 12x18?

Ok not sure why it's not good to have high alkaline. I started seeing a lot of green in the pool so I thought that the chlorine was not working so I added some more baking soda. Now I found out that it's too high. I added some algicide as directed and it cleared up the cloudiness but the floor is still green. I been scrubbing it but it seems to still be there. Suggestions?