Can too much flow exhaust your fish?

Spkarim · Nov 29, 2019

Hi Everyone,

A heart Happy Thanksgiving y'all from Texas

I just got a clownfish in my 40g breeder with 1300 gph and 560 gph circulation pumps that turn on or off only. They are positioned on opposite ends of the tank 3/4 way up facing each other

the new clownfish seems to be swimming really hard in a bottom corner with both pumps on. I turn off the larger one and it doesn't work as hard, swims around more. I have a couple Banggai Cardinals that will also swim out more.

I have some Montis on upper part of reef so want to give them enough flow.

Is is possible the flow is too much, or the fish can handle it? With both pumps on substrate sand basically not moving. Should I get a different pump instead of the larger one, or consider a controller?

Thanks in advance

Tahoe61 · Nov 29, 2019

Interesting question.

I am of the opinion based on my experience with some smaller clowns there can be too much flow. I have decreased flow to allow smaller new clowns to get a couple meals in and acclimate.

naterealbig · Nov 29, 2019

Sometimes when i get a new fish, due to previous system conditions they aren't used to high flow. If the fish seems to be experiencing distress, I'll turn one or more of the circulation pumps off until they get acclimated to the new tank. After that i increases flow over the next couple days.

The clowns will be okay - and willbe happy with the flow in a day or two....

Billdogg · Nov 30, 2019

When all the in-tank circulation is on, my 120DT approaches 100x turnover. What I have found is that it seems like many fish like to "surf" in the outflow . Try to arrange your power heads so that they create a more random flow pattern. The fish will figure them out .

PatW · Nov 30, 2019

You have about 40 times flow. My tank has over 50. None of my fish even relatively poor swimmers like Bengai cardinals never have had trouble with flow.

It depends some on your rock work. Fish can tuck in behind a rock if they want. But I don’t see that much. I have seen fish surf the powerheads. They swim up besides them and then hop into the full blast flow and enjoy the ride. Some of the fish that are decent swimmers swim right into the blast, they get a fishy work out.

I have seen really strong currents at coral reefs with flows far in excess of what you will ever see in an aquarium. And fish do fine.

Eleni18 · Nov 30, 2019

But what about the corals? How do you adjust power heads and flow so they don't blow away?

Billdogg · Dec 1, 2019

All of my power heads are placed about 1/3 - 1/2 of the way down the side and then angled up and towards the center to create as random a flow as possible. Pointing them up also increases the oxygenation of the water making everything happier. If you have LPS or soft corals that seem to be bothered by the flow, try to place them in more protected areas (up close to rockwork, etc)