Looks like I'm going to be away longer than expected this winter, for about a month. I'll have house-sitters staying in my apartment to water plants and take care of my tanks, a 10 gallon w/ an old gourami in it, and a 20 gallon w/ 2 juvenile dwarf gourami and 3 small clown loaches (this group upgrades to a 55 when I return in January). My usual routine is a 25% water change once per week. However I'm considering switching to 10% every 3 days, for two reasons: 1) I think it might be easier on the house-sitters, they'd have to do more frequent changes but would have to deal with only a small volume of water at a time; and 2) there'd be less chance they might shock the fish with sudden water fluctuations. My question, if I change, for example, 2 gallons of water at a time from my 20 gallon, do I add only 1 ml of chlorine/chloramine remover? The dose is 5 ml per 10 gallons, so that's only a half ml per gallon. I guess my related question is, is my proposed 10% change per 3 days adequate? Or excessive? For the sake of the loaches, before they move to a bigger tank, they need to have really clean water. Any opinions of the 10% per 3 day schedule? Suggestions for a different schedule, that'd still be easy and hopefully fool-proof for house-sitters? Thanks!