OCLT shows what you lose overnight when the sun is off the pool. If there is nothing consuming chlorine it should drop less than 1ppm from dusk to dawn. If you are losing more than 1ppm during that time period you have organics consuming the FC and need to slam. Rising pressure may also be an indicator of organics in the water. A nascent algae bloom will give water a dull, grainy appearance before it goes cloudy or full out green.
Next time you clean the filter, inspect the cartridge well. Make sure there are no small holes or tears in the pleats where debris can escape. The bands around the cartridge should be intact and in good condition as well. As Butterfly mentioned skimmer socks can also help catch fine debris in the water.
I may be expressing it incorrectly. The pressure has risen from 10 to 12, a 2psi increase, in a month at 2500 rpm.
Filter cartridge is less than a year old, no holes, only washed with a water jet, no pressure washer. Bands are fine.
I am losing about 1.5 ppm CL in 24 hours. My water is clear, no cloudiness at all, have never had anything close to algae pre or post TFP method.
Just these **** particles!
Thanks for trying to help