My ph levels slowly but continuously rise. I have a raised hot tub that pours into my pool. I like to keep the ph between 7.4-7.6. I have to add a little acid about every 2 weeks. My older brother's pool is almost identical. He lives about 2 miles away. My next-door neighbor and a friend that lives around the corner from my brother both have similar size pools, both with raised hot tubs that spill over into the pool. They both have to add soda ash to increase their ph levels. Their levels run around 7.0 or lower. We all have the same rainfall and water provider. Just odd.