Who Gives A Fish Forums

What's the deal with blackwater aquariums? I've seen 'em around but never tried one. Heard they're good for certain fish, but how do you even start? My tap water's pretty hard, so I'm kinda sketched out about it.

Blackwater tanks are super chill for fish like Bettas or Tetras. You gotta start with RO water or mix in some peat to soften it. My 20 gallon's been running for months with driftwood and Indian Almond leaves, pH stays around 6.5.

The tannins from driftwood and leaves lower pH naturally. I use a mix of RO and tap to hit 6.0 in my tank. Just monitor it weekly, some fish don't like sudden changes.

flintbox wrote: ↑Fri Aug 01, 2025 10:00 pm What's the deal with blackwater aquariums? I've seen 'em around but never tried one. Heard they're good for certain fish, but how do you even start? My tap water's pretty hard, so I'm kinda sketched out about it.

If your tap's hard, definitely dilute with RO. I've kept Discus in blackwater for years, they thrive in soft, acidic conditions. Start slow with the changes, maybe 20% RO per water change.

Blackwater's not just about looks, it's legit better for some species. My Cardinals breed like crazy in it. Just toss in some Oak leaves and let 'em stew, turns the water tea-colored in no time. Super easy if you're patient.

Thanks for the tips, y'all. Gonna grab some leaves and driftwood this weekend. Any specific brands for RO systems, or are they all pretty much the same?

I use a cheapo RO buddy, does the job. Just make sure you remineralize a bit for the fish. My Tetras didn't mind the transition, took about a month to get the water right.

muddy wrote: ↑Sat Aug 02, 2025 12:43 am I use a cheapo RO buddy, does the job. Just make sure you remineralize a bit for the fish. My Tetras didn't mind the transition, took about a month to get the water right.

Agreed, remineralization's key. I add a pinch of Equilibrium to my RO water, keeps the GH around 4-5. Too soft and some plants might struggle.

If you're worried about plants, stick to Anubias or Java Fern. They don't mind the lower light and softer water. My tank's mostly those with a few floaters, everything's thriving.

Yeah, and don't freak if the water looks like weak tea. That's the tannins doing their thing. My buddy thought his tank was dirty at first, now he's all about that blackwater life.