How big of a tank would I need, before I should consider a sump

  • We are currently upgrading MFK. thanks! -neo
Personally I would not use a sump for any tank less than 75 gallons.

In saltwater I'd add one for any tank over 75 gallons.

In fresh I'd add it to any tank over 125 gallons.

That's just my preference. There is no rule. I might even favor canisters in a larger FW tank if it is planted to prevent the off-gassing of CO2.
 
Do you mean the species of fish?
They are Australoheros "Red Ceibal", a cichlid from Uruguay that requires a bit of a cool down period. I kept them in unheated basement in tanks in winter (@50'F), and in the tank, or pond outside spring thru fall in Milwaukee.
The colors in the photo above are spawning colors.
Below is a male in normal coloration, at around 6".

female below
 
My personal opinion on it is if it's a drilled tank run a sump. If it's a saltwater tank, run a sump. If it's a fish room system, run a sump.
 
I literally debated a small sump on my little girls 5g Betta tank. On the 75 I mentioned I also have a algae scrubber and a SS coil that uses my water heater to heat the he tank.
 
I would go sump all the way. Not only is your sump an added amount of water and filtration system, but you could baffle it for injured fish, new fish, and of course fry. I love being able to soak my driftwood in the sump before adding it to the show area of the tank. It adds tannins O your water and let's the wood get the beneficial bacteria from your tank ahead of time. Also letting it get to the point that it will sink. Without a sump on my 55gallon tank my water changes took about 25-30 minutes. Now that I have a sump I can do a 30% water change on my 265gallon in 5 minutes or so. I run a canister as well for the nice flow and mechanical filtration. Go sump all the way man. Worst that can happen is you won't like it, but it will for sure filter your water. So you can't exactly fail.
 
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