kwp

I've got a new-to-me tub, and I've learned an awful lot from this forum. Thank you very much. I did the whole decontamination process, and then got it up and running nicely. Tub is 240 gallons My T/A is 85 My borates level is about 45 ppm pH is around 7.5. I have had to lower it a couple times. CH is around 150 I used dichlor for the first 10 days, then switched to bleach. Here are the two big questions: I had to go away for two days. I raised the F/C to around 13 on Friday night. On Sunday, it had dropped to 0. I've been getting it back up, but it got a little cloudy. I have to go away periodically for two to three days. How do I keep the F/C from dropping to 0 when I'm gone? Also, I'm not quite getting my head around how much bleach to add after use. It's been fine when my wife and I use the tub at night - I just add a couple ounces of bleach and it's fine in the morning. My wife had a party - five women in the tub for 2 hours. It looked like I needed to add 7 ppm per person per hour, which would have been 70 ppm? Is that correct? Thanks for the help. KWP

Hello folks, I have really learned a lot about water chemistry from the posts on this site. Thank you so much for this resource. I purchased a used Phoenix spa, and the filter cartridge is missing. I can't figure out what to get, and the manufacturer is out of business. It's clear I need a - Width: 6" , Length: 8-1/4" ,Bottom: 1-3/4" OD Male Slip, but I can't figure out if I need a closed or open top. I know this is a very basic question, but I'm having trouble getting answers. Any suggestions? Thank you very much, KWP