Q: I have a hot tub with a Balboa 510Z it is coding LF what does that mean. It went from 104 degrees and now is maintaining only 59 degrees.
A: LF - Means persistent low flow problems, spa has had five High limit events in the last 24 hours.
The simplest cause of this is a very dirty filter cartridge. I would pull it out and clean it or replace it if it more than a couple of years old.
On the VS this could also mean a problem with one of the temperature sensors but this is less likely.
If you do need a filter you should be able to find it at the link below: