Hello all. So I backwashed my hayward de 3620 filter this weekend that was running about 19 PSI for about 3 minutes and it cleared a bunch of brown stuff out and was clear. PSI dropped significantly to about 10 and then yesterday it was really low at 6. I cleared the skimmer baskets and main filter catch. I missed adding DE which was a big mistake but did it this AM. So far knock on wood not seeing anything coming out of the returns so hoping I am okay there. Does anyone know is 10 PSI okay or too low and if its too low what should I check or call someone in to take a look at it? Water looks good nice and clear overall.