Out of town for 3 weeks, how to set my tank...

[Bloodasp]

I guess what he is saying is that the garbage bin you will be using will be filled with fresh water. Right now you are topping of your sump 5 galons of water every week if i read that right. The idea of an auto top-off is that you no longer need to manually top off your sump as it is done automatically. every time your water level drops from a certain level water from your reservoir is added to your sump until it reaches the point where the level originally was. This is actually good even to use even when you are around as it eliminates the fluctuation of your salinity level. And from what I understand you top off once a week, that's a huge fluctuation of your salinity level.

[Albertan22]

Bloodasp is correct in what I was meaning. I use the garbage can as a top off reservoir, not the sump. If you used it as a sump and didn't have any topoff, your salinity level would get pretty high as water evaporated over the three weeks and could hurt or kill your livestock.

[ferret]

5 gal for 10 days during such weather! To me 5 gal is only good for 4 days for my fowlr with t5 light fixture set for 6 hrs a day. I experienced your situation too for departing more than 24 days, I ordered the auto-top off from bulk reef supply and completed the hook up by myself and purchased the auto feeder from J/L and to add the activated carbon ( with specified amount good for 30 days ) and all my fish were survived when I returned home from trip. Honestly speaking, to play safe the best way is to look for somebody to babysit your tank.