The deal with vinegar was someone found that it was destructive to plastics that contained magnets. They found that the seams were breached by the vinegar and allowed saltwater and vinegar to get at the magnet.
Vinegar isn't going to dissolve your pump. I've been using vinegar for 25 years to clean pumps and I even have a 20+ year old Tunze pump that has been cleaned in straight vinegar countless times.
But to be on the safe side I did switch to citric acid. It's cheaper and easier to store.
People have been using muriatic acid too.
Straight it will eat plastic after a while, but I used it a couple times and I believe I used 1 cup to a gallon of water.
I also used rubber gloves with this.