At some point it may be ideal to upgrade that filter when time/resources permit. Just some standard PVC plumbing work for the most part. For now you may have to be extra vigilant in cleaning, etc. Swampwoman's latest input was the OLCT and metals testing, so if you've passed the past 3 OCLT successfully, and have no concerns about those tests or how they were performed, then that would leave us to standing-by for any metals testing. When you do make a trip for a test, please make sure you grab a fresh sample of water from the "source", not pool water that was already chlorinated. Nothing says you couldn't grab two sources (pool and well/hose) just to compare, but usually the chlorine interferes with an accurate test.