why is discus tank ph dropping?

[Vista]

My Discus tank pH keeps dropping from 7.0 to 6.0 within a day. I've got a 75-gallon tank with 6 adults, sand substrate, and driftwood. Weekly 50% water changes with RO water, temp at 84°F. Filter is a Fluval FX4, no CO2. Tankmates are 10 Cardinals and 6 Corydoras. Feeding twice daily with frozen bloodworms and beef heart. No recent changes except adding a new piece of driftwood last week. Any ideas?

[subway]

Driftwood can definitely mess with pH, especially if it's new. It releases tannins which lower pH over time. How long did you soak it before adding? Also, RO water has no buffering capacity, so it's prone to swings. Try mixing in some tap water or adding crushed coral to stabilize it. What's your KH reading? If it's below 3, that's your issue.

[TankWarrior]

Yep, subway's spot on. RO water's sketchy for Discus unless you remineralize. I run a mix of 70% RO and 30% tap to keep things chill. Also, check your filter media. If it's packed with bio balls or ceramic rings, they can acidify over time. Swap some out for fresh ones or add a bag of crushed coral in the filter.

[Coralite]

Driftwood can definitely mess with pH, especially if it's new. It releases tannins which lower pH over time. How long did you soak it before adding? Also, RO water has no buffering capacity, so it's prone to swings. Try mixing in some tap water or adding crushed coral to stabilize it. What's your KH reading? If it's below 3, that's your issue.

Totally agree! Vista, how's your fish behaving? If they're gasping or hiding, it's a sign the pH drop's stressing them. I'd do a small water change with tap mix ASAP to buffer it.

[Vista]

Thanks, everyone. I only soaked the driftwood for 2 days, guess that wasn't enough. Fish seem okay but a bit less active. KH is at 2, so that's probably the culprit. Gonna try mixing in tap water and adding coral. Appreciate the help!

[Wildman]

KH of 2's way too low for Discus. Aim for 4-6 to keep pH stable. Also, cut back on the beef heart. It's high in protein and can spike organics, which bacteria break down into acids. Switch to more balanced foods like Hikari Bio-Gold or Discus pellets.

[Purrer]

Yo, my tank did the same thing last month. Added a bag of aragonite sand in the filter, fixed it in like 3 days. Cheap fix, works like a charm. Also, test your tap water's pH after sitting out for 24 hours. Sometimes it's lower than you think.

[Lyn]

What's your water change schedule like? If you're doing big changes with pure RO, the pH's gonna swing hard. Try smaller, more frequent changes, like 20% every other day. And yeah, buffer that water. Discus ain't fans of rollercoaster pH.

[mistysea]

I had this issue too. Turned out my substrate was holding a ton of waste, even with vacuuming. Switched to bare bottom and pH stabilized. Maybe check under your sand for gunk buildup?

[darksage]

Yep, subway's spot on. RO water's sketchy for Discus unless you remineralize. I run a mix of 70% RO and 30% tap to keep things chill. Also, check your filter media. If it's packed with bio balls or ceramic rings, they can acidify over time. Swap some out for fresh ones or add a bag of crushed coral in the filter.

This. Also, consider a pH controller if swings keep happening. They're pricey but worth it for long-term stability.