Tagelus TA 60D sand filter, 6 port valve, 5 years old, low load - 2 people, on/off pressure differential = 18 psi. Backwashing/rinse cycle makes little difference. I do not accurately remember last years reading, but this seems much higher and there is a marker ring on pressure gauge that says "clean" after 10 psi differential.
I tried using a chemical sand cleaner (GLB Filter Fresh), but may have inadvertently left timer on and short circuited the procedure. But: The procedure for filling the tank with the cleaner seems to me to be very imprecise; empty tank, pour in cleaning solution into opened lint pot with pump on, shut pump and wait 12 hours. The instructions are for all tanks regardless of size. So, I do not know how much of the sand is actually covered by the solution. Tagelus manual is very vague about this and tech support even vaguer.
I have seen reference to removing the valve and manually agitating the sand. I see no way of doing this without cutting all (except pipe to pump w/ union) all connecting pipes. (Is there a industry standard for installing unions to facilitate servicing?)
So, do I re-try the chemical cleaning (and do it right this time)? How much do I use? Is there a 'best' product for this? Other solutions?