Ona does work wonders, but if you have the funds an activated carbon filter is ideal. If you must leave before a flowering period is done and you're growing in soil you can create a drip system which i was forced to do once. Buy an adapter for the nearest faucet, and if it's not close get a garden hose, then get a barbed adapter to connect it to a air line hose that would be used for air stones. run that line near the base of each potted plant. Secure the line with clothespin, duck tape...etc. Fold the very end of the air line or cap it. Use a needle or a nail, and this will take a little testing, DO NOT make the holes too big, this will make it so the first plant is the only one to get water, but punch about three holes in the line per pot. Then turn your faucet on a drip. The pressure that builds from the water will keep all of your plants moist while you are away. I had 8 plants survive out of ten while i was gone for a week. Can also use an RO system which has low flow and would also be easier to adapt.