I have an RO
system. It is a water purification system that you connect to a fresh water source. It does not clean water from your tank to be reused. What it does is purify fresh water so that you can then add the salt and use it for water changes. When using my system, I do not have to condition the water to remove chlorine, the system removes it for me.
My system is a six-stage system. It has a faucet on top of the sink so that my family can get clean water, then it has tubing with a little faucet that is under the sink. I just stretch out that tubing into a bucket, turn on the little faucet to get water for water changes. To the bucket (after adding the water) I add the salt mix, stick in a powerhead or airline tubing and heater to get the water oxygenated and heated to the proper temperature.
I got my system on ebay from... it's either general manufacturing or manufacturing general (that's the manufacturer, no the vendor) but you can do a search on RO
systems and you'll see them. There is a product review on this site about it. I paid about $100 for it, but you can get them for a little less, I believe.
, you do not have to add the faucet to the sink top if you don't have a hole for it and don't want to drill it. You can just cap off the tube that would go to the faucet and only use the under-sink faucet if you want. It's still clean water to drink or for water changes. PM if questions, I can probably find a link on ebay for you if you're interested.