so the prefilter would go after your pump but before your feed lines
so your pump should have some type of foam filter and then what ever gets through the pump gets filtered by the inline so as not to clog the drip baskets/lines/manifold
you can pull the filter off the pump and clean it but if you are using something like
mammoth P I would keep that filter the way it is as it will collect and harbor biologicals
which are good and need to stay active in the res until you are done with this run
but the inline will filter out any chunky stuff or flakey stuff if there is any
17.00 for piece of mind