Who Gives A Fish Forums

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.

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?

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.

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?

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.

Thanks all. I do 30% changes twice a week, temp's 84°F. I'll grab an RO unit this weekend. Appreciate the specifics!

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.

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.

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.

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.