Simply put, TFPC is a methodology that is proven by thousands of pool owners on this forum. It is not what the pool store is telling you so it takes a different frame of reference to accept this methodology. Thousands of forum members have crystal clear water and have never had algae. Others have posted videos on specifics of your issues but it may be best for your husband to read the following linkI tried explaining it to my husband and he doesn't understand if our FC is high why we are adding more chlorine and I am having a hard time explaining it to him.
What is TFPC? - Trouble Free Pool | Trouble Free Pool