Generic filters are those that do not have a recognizable brand name attached to the filter. They could also be filters made by a top filter manufacturer under an OEM (other equipment manufacturer) label.
Similar to drug store generic drugs or supermarket generic items, sometimes the generic is actually made by a brand name manufacturer who is putting out either a discount line or just marketing through different channels.
Sometimes the brand name manufacturer can custom make a filter type for the OEM application so it could be a custom filter not available through the manufacturers own brand.
Find discounted replacement spa filters for your hot tub right here at Spa Filters Canada. There are even good deals on brand name filters available online.
There are quality generic filters that use Reemay paper material and there are cheap generics that use lesser filter paper such as some of the ones found elsewhere online. Since it is the paper that is doing the filtering, this component should be high quality Reemay or equivalent. Note that the filter is disposed of every year or so anyway, so surely most plastic end caps will last that long unless you are planning on using the same filter for several years (not recommended by most manufacturers).
By the time the end cap deteriorates, the filter paper is usually long overdue for a change anyways. However if you begin with cheap paper in a new filter, filtration may not be optimum at all, and that can affect hot tub performance as well as not clean and filter the water very well which can cause further equipment problems not to mention water quality issues.
Look for the Reemay brand of filter paper in your replacement hot tub filter replacement cartridges.