best discus tank water hardness

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angelic
Posts: 22
Joined: Sun Jun 16, 2024 5:46 pm

best discus tank water hardness

Post by angelic »

What's the ideal water hardness for Discus? I've got a 75-gallon tank with 6 adults, sand substrate, and a canister filter. pH is stable at 6.8, but my GH is 8 and KH is 4. They're eating well but seem less vibrant lately.
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Playful
Posts: 13
Joined: Thu Oct 10, 2024 12:42 am

Re: best discus tank water hardness

Post by Playful »

Aim for GH around 3-6 and KH 1-3. Higher hardness can stress them long-term. I keep mine at GH 4, KH 2 in a 120-gallon with driftwood and RO water. How often are you doing water changes?
midas
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Joined: Sun Jul 03, 2022 4:22 am

Re: best discus tank water hardness

Post by midas »

Yep, softer water's better for 'em. I mix tap with RO to hit GH 5. My crew's in a 90-gallon with weekly 50% changes. What's your temp at? They dig it warm, like 84-86°F.
Cloudy
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Joined: Fri Aug 02, 2024 6:21 am

Re: best discus tank water hardness

Post by Cloudy »

midas wrote: Sun Aug 31, 2025 3:47 pm Yep, softer water's better for 'em. I mix tap with RO to hit GH 5. My crew's in a 90-gallon with weekly 50% changes. What's your temp at? They dig it warm, like 84-86°F.
Temp's key! Mine are at 85°F with a backup heater. Angelic, you gonna try RO?
talon
Posts: 20
Joined: Thu Oct 10, 2024 2:05 pm

Re: best discus tank water hardness

Post by talon »

Weird vibe but my Discus bred at GH 7 once. Tank's planted with CO2, and I dose minerals lightly. Maybe it's your lighting? I run LEDs 8 hours/day.
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angelic
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Re: best discus tank water hardness

Post by angelic »

Thanks all. I do 30% changes twice a week, temp's 84°F. I'll grab an RO unit this weekend. Appreciate the specifics!
Hued
Posts: 21
Joined: Thu Aug 03, 2023 8:36 am

Re: best discus tank water hardness

Post by Hued »

Sketchy tap water here, so I go full RO with Seachem Replenish. My 55's got GH 3, KH 1, and they're popping color like crazy. Fed beef heart mix daily.
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jennyfish
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Joined: Wed Sep 11, 2024 5:27 pm

Re: best discus tank water hardness

Post by jennyfish »

Or just... don't stress? Mine are in harder water (GH 10) and just vibing. Then again, they're tank-raised beasts. Wild types might cut it different.
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abbeytone
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Re: best discus tank water hardness

Post by abbeytone »

Hued wrote: Sun Aug 31, 2025 7:12 pm Sketchy tap water here, so I go full RO with Seachem Replenish. My 55's got GH 3, KH 1, and they're popping color like crazy. Fed beef heart mix daily.
How often you change filters? My canister clogs fast with that beef heart.
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joshito
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Joined: Wed Mar 09, 2022 12:46 pm

Re: best discus tank water hardness

Post by joshito »

Yo, my LFS said hardness don't matter if pH is low. That legit? Got a 40-gallon with 4 juvies, sponge filter, and they're growing slow.
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