Using a Nature 2 system with the BBB method

[waterbear]

My Pump motor is the 1 HP A.O. Smith 1081 design ST1102 single speed motor
Are the motor and filter sized right for each other?

Looks like I have the 3/4 HP Hayward STX 2600 super pump

STX2600 is not a valid model number for a Hayward Super Pump. Possible models are:

SP2600X5 (1/2 HP up rate rate)
SP2605X7 (3/4 HP up rate -- 1/2 HP full rate)
SP2607X10 (1 HP up rate -- 3/4 HP full rate)

Houston we have a problem. The AOsmith motor is a replacement and it is a FULL RATED 1 hp motor. If your pump wet end says it's a 3/4 hp then your motor is oversized for your wet end. It is VERY oversized for the wet end since the superpump line is all uprated so this that would be a .5 hp wet end.

IF your pump is Model 2610X15 which the the uprated 1.5 hp superpump (equivalent to a 1 hp full rated pump) then the motor is correct for the wet end.

This could explain why your filter is not working properly. How long ago was the pump motor change out?