Re: Does a Polaris 280 cleaner need a separate cartridge fil
There are different ways the system can be setup. The most common approach is to use just the one normal filter and then after the filter split the line to returns and the cleaner. However, some setups split the line before the main filter, putting a more efficient small filter on the pressure side cleaner line and the usual main filter on the primary line. This setup is just slightly more efficient, as the cleaner doesn't get the pressure loss of the main filter and instead only has the much smaller pressure loss of the small high efficiency filter. However, it adds complexity and requires you to clean the small filter in addition to the main filter.
While it is pointless, I have also seen people use a small secondary filter on a pressure side cleaner that splits off after the main filter. This presumably comes from plumbers mixing up the two normal plumbing diagrams and using elements from each one. In this setup the small secondary filter serves no purpose, because the main filter has already caught everything that the secondary filter could possibly catch.