filter gauge valve

Opened pool 2 days ago so still a little cloudy and green. My question is this, backwashed DE filter and pump running for approx 4 hours, gauge has not increased? Not a novice to pools, but new house, new set up has me baffled. 2 times the system has indicated low flow and shut off. Wondering...

Our filter pressure gauge/air valve was spraying water and then I completely broke it off. Couldn’t find one at pool store so we ordered one online—but it will be about a week and a half. Of course we’d like to keep using the pool and circulating the water. Is there some kind of plug we can use...