This question--in one form or another--has been addressed a number of times in this forum, but I'm still seeking guidance. (Which may ultimately be: repeating the question doesn't change the answer...)
Anyway: I have to leave my spa unattended for a full calendar month this winter. Where I live it's often well below freezing for days at a time. Getting someone to come and make tests and periodic adjustments to the water while I'm gone is problematic. (Read: not impossible, but inconvenient and probably expensive.)
Right before leaving, I plan to clean and refill the spa, and replace the filters. I'll set the temp to something reasonable, maybe 90 deg F or so.
Given that this pristine refill will not be used in my absence, what are the (likely) chemical/biological consequences of leaving the spa unattended for a winter month? Is algae growth likely? Does there exist an initial chemical adjustment that would minimize deleterious consequences after a month unattended? I'm OK with doing a cleanup and refill when I return; I just don't want to permanently damage any spa components.
Out of the tap, my municipal water is about pH=8, CH=70, and TA=70.
I know the safest thing to do is, "hire a service or winterize the spa." Failing that, I'm looking for the next-safest thing (if there is one).
Thanks in advance,