Dont waste $$ on change the pump flow rate.
This model call for min 1200 l/h to ..... as long as within the spec will be fine.
I use same model as you.
My inital set up same thing happen kick in very offen(can't remember clearly.... every 20~25 min kick in once).
After do some search in this furom, install the 'External thermostat' will slove your problem.
I think this is something do to with this chiller design. If you observe carefully, once the chiller kick in, the temp display/measure on the unit very fast drop down 1~2 deg! This can't be happen.....
Go and get the external thernostat install....
Cheer