Welcome to our forum.
We get a pile of foam every time we crank up the jets...haven't used in 2 days, walk out and turn on jets and might well throw the cloths in.Would this be why you need to empty tub and refill after one month?
....and no suits is even better....
We were cruising along after 4-weeks in clear water until my son's friends came over in their laundered trunks. Worse foam we've ever had and it appeared the next night when I went to get in!