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I've got a 75 gallon tank with 6 Discus, all around 4 inches. The water flow seems too strong, they're struggling to swim near the filter output. Using a Fluval 407, but I'm not sure if I should adjust the flow rate or add something to diffuse it. Anyone dealt with this before?

The Fluval 407 can be pretty powerful for Discus. I'd recommend reducing the flow rate to about 50%, they prefer calm water. Also, try adding a spray bar to distribute the flow more evenly. What's your substrate? Sand helps buffer the current too.

Yep, gotta agree with jason. Discus aren't fans of strong currents. I run my 407 at half power in my 90 gallon, and they're way happier. Also, check your water temp, they like it warm, around 84°F.

jason wrote: ↑Sun May 18, 2025 3:06 pm The Fluval 407 can be pretty powerful for Discus. I'd recommend reducing the flow rate to about 50%, they prefer calm water. Also, try adding a spray bar to distribute the flow more evenly. What's your substrate? Sand helps buffer the current too.

Spot on. I've got the same setup, and adding a sponge filter near the output helped a ton. They're chillin' now.

If you're worried about oxygenation with lower flow, add an air stone. Discus need stable O2 levels, especially in warmer water. Also, what's your water change routine? Frequent changes help keep them stress-free.

Thanks for the tips, everyone. I'll dial down the flow and look into a spray bar. Doing 30% water changes twice a week, temp is steady at 84°F. Substrate is sand, so that's good.

Another thing to consider is tankmates. If you've got fast swimmers like tetras, they might be stirring up the water too much. Discus prefer calm buddies like Corydoras.

My Discus were acting weird too, turns out the flow was too strong. I just stuck a piece of filter sponge over the output, and it worked like a charm. Cheap fix!

hanksid wrote: ↑Sun May 18, 2025 10:38 pm My Discus were acting weird too, turns out the flow was too strong. I just stuck a piece of filter sponge over the output, and it worked like a charm. Cheap fix!

That's a solid hack. I'd also recommend checking your filter media, clogged sponges can mess with flow.

How's your lighting setup? Bright lights can stress them out if the water's too turbulent. I keep mine dim with floating plants to diffuse the light and flow.