We are leaving a week from tomorrow for 8 days for spring break. Our fish sitters will be my parents, who are very conscientious about feedings but have had some issues in the past with water changes. Historically, we have had 3 fish get sick and/or die within a week of my parents caring for them (ugh).
Currently, we have just one betta, who has been with us for about 1.5 yrs, living in a 2.5 heated (~78-80 degrees), unfiltered tank. We plan to do 100% water change just before leaving on either Sun night or Mon morning.
Which of the following options do you think would be best, given history described above:
1) Don't have fish sitters perform any water changes, ask them to siphon out any obvious waste (tank has no substrate so should be fairly easy to spot) and do 100% water change immediately upon return following Mon
2) Set up before leaving a 2nd tank/heater with 1.25G of pre-conditioned water for 50% water change mid-week, ensure temp is equivalent to that of main tank, and instruct fish sitters to remove 50% of water on Thurs or Fri and replace with water from 2nd tank; still plan to do 100% water change upon return following Mon. If we go with this plan, is there any issue with leaving the replacement water just sitting for a few days?
3) something else I may not be thinking of???
Fish is currently healthy, seems to be fully recovered from a recent injury (scraped himself on something and knocked off a chunk of scales - was not himself at all for a few days but now looks fully healed and behavior has been back to normal for at least 2 wks now - never figured out how it happened though) - otherwise no recent history of illness.
TIA for any advice anyone may have!