Note: the below is if you didn't add the clarifier already - if you did, this may contradict the clarifier's instructions as to FC
This just seems like a classic case of too little FC - which we will handle once and for all when you get back.
For now: When he can, and when the pump is running and will be running for at least 20 minutes, have your son SLOWLY pour 3 gallons in today, then a gallon tomorrow. If he has less than that available, just put what he has in there, no worries. No reduction to SWG or pump run time.
Then put it out of your mind and have a wonderful trip, trusting we will get this sorted and on cruise control once and for all when you return.