So I have a pool I work on for a guy. This site has taught me a lot about the pool, and I've gotten it sparkling. Now I have an odd problem. Pool is somewhere around 45-50,000 gallons I believe. I have a 200# sand Hayward filter that's only 3-4 years old. I changed the sand in the filter at the beginning of the season. The pressure is a bit higher than last year about 19-20psi with the solar heaters running. I remember last year it was somewhere around 15psi. I didn't think much of this until I recently had an algae bloom and had to shock it. The water is still cloudy, and it's been over a week. Last year it was 2-3 days. What would cause this ? Is something not right internally?