I have a Bacquapure sand filter that was given to me about 6 years ago. It has ran great all up till now. When I started it up this year I noticed a small leak under the split nut ring and didn't pay it much attention. About a week went by and my wife told me it was leaking and the pool level dropped. I unplugged the pump and the small leak was now spraying. I ordered a new o-ring and a new split nut ring. While it was down, I changed the sand and cleaned the laterals. I could not change the split nut ring out so I just used the old and it didn't want to come off as well. I tightened it down and did a backwash for the new sand for about 3 mins and there were no leaks. I turned the pump off and switched to filter after I did a rinse and it went to spraying like before. We have our daughters Sweet 16 this Saturday and we are stressing. Any ideas?