Who Gives A Fish Forums

I've got a 75-gallon tank with six Discus, all around 4 inches. The water flow from my canister filter feels too strong, and they're avoiding one side of the tank. Should I adjust the flow direction or add something to diffuse it? Tank's got sand substrate, driftwood, and a few Amazon swords. Parameters are stable, 0 ammonia, 0 nitrite, 5 nitrate, pH 6.8. Temp's at 84°F.

Yep, strong flow can sketch them out. I'd point the output toward the glass or add a pre-filter sponge to cut the current. My Discus chilled out after I did that in my 60-gallon. Also, check if the driftwood's blocking flow unevenly. What kinda canister you running?

Aw, poor babies! Mine hid for days when I cranked the flow too high. Maybe try angling it upward so it breaks the surface? That helped mine feel safer. Btw, love that you've got Amazon swords—they're such vibe setters. How often you do water changes?

coralCartel wrote: ↑Thu Jul 03, 2025 5:25 pm Yep, strong flow can sketch them out. I'd point the output toward the glass or add a pre-filter sponge to cut the current. My Discus chilled out after I did that in my 60-gallon. Also, check if the driftwood's blocking flow unevenly. What kinda canister you running?

Totally agree. I use a spray bar on my FX6 to distribute flow evenly. Also, 84°F is solid, but watch for temp swings if you redirect flow near the heater. What's your lighting schedule like? Bright lights plus high flow can stress them.

The filter is a Fluval 407. Flow rate is 383 GPH. I have adjusted the direction toward the surface. The driftwood is not blocking flow. Water changes are 30% twice weekly.

Thanks for the tips, everyone! Gonna try the pre-filter sponge and angle the output upward. Lights are on 8 hours a day, low intensity. Appreciate the help.

Nice, Fluval's a beast. If the sponge doesn't cut it, you could also mess with the valve to dial back the GPH. My Discus started schooling more after I tweaked mine. You got any dither fish in there?

Sunnyday wrote: ↑Thu Jul 03, 2025 9:07 pm Thanks for the tips, everyone! Gonna try the pre-filter sponge and angle the output upward. Lights are on 8 hours a day, low intensity. Appreciate the help.

Keep us posted! Mine took about a week to adjust after flow changes. Also, twice-weekly water changes? You're on top of it—that's probably why your params are so stable.

8-hour lighting's perfect. Just watch for algae if you're redirecting flow toward the surface. Oh, and if you add the sponge, rinse it in tank water during changes. Tap chlorine'll wreck the bacteria. What's your substrate depth? Too deep can trap debris with high flow.

Substrate is 1 inch deep. No dither fish. Tankmates are 10 cardinal tetras and 6 corydoras. The tetras seem unaffected by the flow.