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I've been topping off my 20-gallon tank with tap water for months, but my nitrates keep creeping up. Should I switch to RO water or just do more frequent water changes? My tank has a mix of live plants and a few Neon Tetras.

Topping off with tap water is fine if your tap params are good, but evaporation leaves behind minerals and nitrates. RO water avoids this, but you'll need to remineralize. How often are you doing water changes now?

I had the same issue. Switched to RO and my plants started looking better. Tetras seem happier too. Just gotta watch the GH and KH.

Or you could just drink the tap water yourself and give the fish the good stuff. Kidding, kinda. But seriously, RO is the way to go if you're lazy like me and hate water changes.

tigerlog wrote: ↑Thu Jul 03, 2025 9:56 am Topping off with tap water is fine if your tap params are good, but evaporation leaves behind minerals and nitrates. RO water avoids this, but you'll need to remineralize. How often are you doing water changes now?

I'm doing 20% weekly changes. Tap water here is pretty hard, so maybe RO is worth the hassle.

Hard water can mess with plants. My Anubias stopped growing until I switched to RO. Now they're thriving. Just add a pinch of Seachem Equilibrium.

I use half tap, half RO. Keeps things stable without going full chemistry lab. My tank's chill, fish are fine, plants are growing slow but steady.

My LFS guy said topping off with tap is sketchy long-term. He's got a point, but RO setups are pricey. Maybe start with distilled from the store?

Distilled works in a pinch, but RO is cheaper long-term. I got a cheap unit online for under $100. Worth it if you're in this hobby for the long haul.

briarbrook wrote: ↑Thu Jul 03, 2025 11:03 am Or you could just drink the tap water yourself and give the fish the good stuff. Kidding, kinda. But seriously, RO is the way to go if you're lazy like me and hate water changes.

RO does save time, but you still need to monitor minerals. I test GH and KH weekly to avoid swings.