To add to what aylad said about Alkalinity; high Alkalinity will tend to contribute to CO2 outgassing and the pH rise seen in many SWCG pools. The fix for High Alk. and high pH is the same: add acid. Both pH and Alk. will drop. pH will rise on it's own through aeration and SWCG use. When it gets higher again, add acid again and so on until your Alk is where you want it.

Also to add to aylad's sanitary advice; you have a tiny pool. A little is alot in 1,200 gallons of water. Any sort of "dirty" especially from poo-sickness, I'd shock and close the pool for a couple days.