Is a filter designed for "up to 40 gallons" ok for a 20 gallon tank?

[Eric]

I have a fluval 205, and I would like to use a 20 gallon long fish tank. Is it ok if the filter is meant for up to 40 gallons if I am only using a 20 gallon tank?

[angyles]

on any aquarium, turning the water over 8-9 times an hour is quite a bit. While that would be great in a lot of aquarium setups, I wouldn't do it for anything that doesn't like water movement, like an axolotyl, puffer, etc.
A lot of canister filters have a method for adjusting the water flow. Does this one have anything for that?

[gethin17]

i have the ' fluval 105 ' in my tank, im not sure how many gallons it is ( im guessing about 15 gal) its 61 x 30 x 31cm which is about 24 x 12 x 12".

In my tank i have one leucistic axolotl and a goldfish. ( i know you are not suposed to have the two in the same tank but i have had them both together since last june and there getting along famously).
The ' fluval 105 ' has delt with the notoriously messy axolotl and the goldfish's waste with great success, keeping the tank's water exceptionally clear.
Also the 105 does not cause a extremely fast water flow as to not expose what ever you happen to have in your tank to excess amounts of stress, however the ' fluval 205 ' is made for a minimum of 100ltrs and a max of 400ltrs (source Fluval 205 - AquariumSuperstore - The UK's Leading Online Aquatic Retailer )
your tank might just about make it into the minimum requirements but i can see it being like a whirlpool inside your tank once you switch the filter on.

in my opinion you would be far better off with a 105 ( which has a 25 us gal max capacity ) which means it is an ideal capacity filter for your tank. let me know if this has been of any help (or not)
good luck with your predicament

all the best :
Gethin£49.95 RRP: £99.95

[Eric]

Yeah, thank you both for the help. I think I am gonna either continue to use the 37Gal I currently have set up, or downgrade to a 29 gal, as they both have the same base measurements so my stand would accommodate either. Thanks!