Water changes and aquarium size.

neonk

I ran a 10 gallon tank succesfully for years on 20% water changes monthly. I only had small fish (neon tetras) and an aquarium crab though. So generally speaking in a tank half the size with similar stocking should the water changes be increased? How does this work?

Sanguinefox

Sounds strange doesn't it? The way it works though is quite simple. Larger tanks have more stable environments. Smaller tanks don't. Though that's not quite the case here.

If you have lets say X fish in 10 gallon they are putting out (insert amount of waste) into ten gallons of water.

Now imagine you take the same X fish and put them in a five gallon. Now they are still putting out (insert amount of waste). Your water is now taking in across five gallons what used to go into 10 gallons. The water gets more dirty faster. Thus you have to do water changes more often (or potentially more water per water change). Smaller tanks reach their limit's water wise faster than bigger ones. It's why smaller tanks are actually often more difficult to keep going versus larger ones.

Tazman

fish also give off chemicals to attract potential mates and deter predators, these are also removed in water changes.

neonk

I forgot to add that the ratio of fish to water will be the same, so I will have half the amount of fish as I did in the 10 gallon. Will the 5 gallon still require more water changes just because it is smaller?

Sanguinefox

What fish are you planning to put in there? A five gallon really doesn't hold much to begin with.

neonk

Either a couple of neons or some catfish

Sanguinefox

Cat fish? What specific species?

Tazman

None in a 5g tank...

neonk

Smaller ones like corys

Tazman

Tank is too small for any catfish..sorry.