output passive low pass filter selection

I am using AD628ARZ to design a AC CT signal ADC circuit. CT is millivolt output (-1V to 1V). After CT current signal pass through AD628ARZ, I put another MC1458P (voltage follower), the output of MC1458P goes to a RC low pass filter ( 10kohm and 5100pF, cutoff frequency 3100 Hz). I know my unit has switch power supply and also get a lot of noise on CT signals, after I put RC filter, I got big improvement, but I still have some noise at the peak of waveform shown below:

I got a suggestion to add inductor parallel with R25 because capacitor gets short circuit when signal is at the peak, I don't know how to choose inductor parameters, anybody has some idea? or there are some other solution?

Thank you so much!