How does your life work with a R/O water filter for fish tanks?

Jan Cavalieri

Pet of the Month!
Jun 2, 2019
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Topeka, KS
I have so many water problems - I was so scientific about how I cycled my tanks and now two have completely lost their cycle (the two others did too but I managed to get them back under control - knock on wood). But I get the feeling everybody is sick of hearing about my outrageous ammonia numbers (8.0ppm but they are really the safe ammonium rather than ammonia so the API kit LIES) as well as my super high PH numbers (in the 9's)

Our city water averages a PH of 9.4 has loose ammonia of 1-1.5 ppm, and even nitrates (although I haven't detected it). GH average is 10.6 and KH average is 5.3 (but with a range of 2.6-7.7).

Anyway - eventually everybody ends up telling me to get a Reverse Osmosis system for my water source but the more I read about them the more time consuming it would seem to be to do water changes - and I'm not even sure if their output is what fish really need to be swimming in and not one mention ammonia or ammonium. So

1. I rent so I'll need a countertop model. I seem to have the right kind of faucet but isn't 20 minutes to make 1 gallon way too long when you need 80 gallons?

2 Where do you store your water or how do you transfer it to your aquariums without your house looking like a fish store?

3. Not one that I've read about have mentioned removing ammonia or ammonium - which is my problem. They all mention removing Nitrates. I've NEVER had trouble with Nitrates - and if you do regular water changes you never will. Unfortunately that doesn't seem to work with ammonia and ammonium - you have to wait for them to get converted to Nitrites then Nitrates. I don't believe an R/O system cycles your tank for you.

4. Do R/O systems remove ammonia at all? Not one of the systems - even the ultra expensive whole house models seem to remove ammonia. My city water has ammonia in it - I want it removed. I don't need more ammonia being added when I can't get rid of the amount I have.

5. Is it very important to remineralize your water? I know it's very unhealthy for humans to drink distilled water which also lacks minerals because it actually will dehydrate you. Isn't some calcium and magnesium and salt needed in your water. I read about one high dollar system (under sink) the specifically mentioned remineralizing the water with "good minerals" in "good amounts". I've also tasted distilled water and it was terrible - the lack of salt made it undrinkable and the "softness" made it kind of stick to your tongue.

6. How do you keep the temperature the same as your tank when doing a water change? I know some of the high dollar under-sink models do have a water heater but I doubt any of the countertop ones do.

7. Do they all adjust the ph to 7 or is that just the more expensive ones. Oh, then I read about one system that adjusts it to about 8.5 and says it's perfect for water tanks (maybe salt water but not fresh)

8. Just in general terms describe how you go about doing a water change with an R/O water system in your house. I just can't seem to imagine it.

As many problems as I've had with my tanks becoming uncycled and my crazy PH levels (which I treat carefully with chemicals) I've never killed a fish because of my water. (there was that lid I dropped on one once (cringe). So all I'm wanting is something that allows me to go 2 weeks once in a blue moon without doing water changes every week (or more often twice a week). I'm wanting something that doesn't kill my back and exhaust me by moving buckets of water around (I have back problems and I'm also on oxygen 24/7). And something that will absolutely help me get rid of the ammonia in my tank water by removing it from my tap water. And something that won't require me playing around with PH levels when there are fish in the tank. Heating would be nice, but my tanks are fairly small and have great fast heaters.