Who Gives A Fish Forums

My Discus fry tank pH keeps swinging from 6.8 to 7.4 despite using RO water and buffering substrate. I do 30% water changes every other day, tank is 40 gallons, sponge filter only, temp at 84F. Anyone else dealt with this? Can't seem to lock it down.

Yo, that's a wild swing, dude. I'd check your KH first, sounds like it's too low to hold the pH steady. My 55-gallon stays rock solid at 6.5 with crushed coral in the filter. Maybe toss some in a media bag?

BoldOne wrote: ↑Thu Jul 31, 2025 2:31 am Yo, that's a wild swing, dude. I'd check your KH first, sounds like it's too low to hold the pH steady. My 55-gallon stays rock solid at 6.5 with crushed coral in the filter. Maybe toss some in a media bag?

For real, crushed coral's a game-changer! I use it in my 30-gallon breeder, keeps things chill at 6.8. Also, how often you cleaning that sponge filter? Gunk buildup can mess with params.

Or just stop obsessing over pH. Wild Discus live in rivers that swing daily. Mine thrive at 7.2, and I don't even use RO. Maybe your fish are just... adaptable? *shrug*

Appreciate the tips. I'll test KH tonight and try the coral. Forgot to mention I'm using Seachem Acid Buffer, but maybe it's overkill.

Acid Buffer's sketchy with fry, man. Had a batch crash on me once after overdosing. Stick to natural buffers like the coral or driftwood. Less risky, ya know?

Totally agree! Driftwood's my go-to. My tannins keep the pH around 6.6, and the fry seem to dig the darker water. Plus, it looks rad.

bowsar wrote: ↑Thu Jul 31, 2025 8:20 am Totally agree! Driftwood's my go-to. My tannins keep the pH around 6.6, and the fry seem to dig the darker water. Plus, it looks rad.

Unless you hate the 'tea-stained' vibe. Some folks freak out over yellow water, but hey, fish don't care about Instagram aesthetics.