At the end of my rope with this pool for 4-5 weeks of this now. I have kept this pool at slam shock level and its fine but as soon as it drops to level of 10 algae begins to grow back. Now I have slammed this pool for 2 weeks now begin to let the levels drop and this morning here are my results and I can see algae forming again. Any advice??? Why is this happening? I literally have not used this pool in weeks because it just keeps growing back as soon as I let the levels drop below slam level. Initially I was thinking it was the filter so I have someone coming today to check the filter out but I would think if its filtering at the right the PSI its working? Any advice why it keeps growing back below slam levels for this long?