We have a 20,000 gallon in ground liner pool with DE filtration. Our water chemistry is fine with everything in normal ranges. Testing for Phosphates gives a reading of over 2.5 PPM (2500 ppb) Is this something we should be concerned about or does it not really matter. Not sure where the phosphate is coming from. We have trees near the pool, but keep the pool clean and vacuum every day to keep dirt and debris out. Do we need to take measures to reduce the phosphate level?