JVzer0

Hi,

I just have a general question about canister filters. I have read that your filter should turn over the full volume of your aquarium water at least 5 times an hour. However, all the canister filters I look at are rated for aquarium volumes far too high for them to turn over in 12 minutes. Here's an example:

http://www.drsfostersmith.com/Produc...3&N=2004+22777

If you click on 'more information' you can see that all three of these filters are rated for water volumes that they couldn't even turn over twice in an hour.

I know that usually filters are recommended (by their manufacturer/seller) for volumes higher than it is best to use them for, but this seems to be taken to a different level with canister filters.

Is there something different about them? I know they have more surface area for bacterial colonies, but that shouldn't make a difference in terms of water flow.

SereneReyn

well, i've never heard the 5 times an hour thing... but in the past, whenever i've gone to buy a new filter, i've always gone with something that was around 3 times higher than whatever the box recommended... (ie, for a 50g tank, i would go with a filter rated for 150g tank)

after reading this post, i checked what my actual turn over would be if the filter were running at optimum GPH speed... turned out to be really close to 5x per hour. /shrug

the one thing that i do like about the canister filters is that you can use whatever media you want, in whatever order... you have your sponges/floss... the bio-material, and the option of carbon if your tank needs it. HOB filters, it's alot harder to break it down that much, imo - and the sheer difference in quantity of media is quite large as well.

i know i didn't answer your question at all, but i'd be just as interested in hearing what others (who probably know a lot more than me) have to say.

susitna-flower

I believe the rule of thumb for HOB filters are 10 X tank size for gph. if your than was 55gallons it should turn over 550 g/h. That does not hold for canister filters. I would try for 5X but as SereneReyn said more is better, but this all depends on your budget.

Sometimes it is cost effective to use an extra HOB to eliminate dead spots, or add more turnover if it is needed beyond your canister filter.

JVzer0

Thanks for the replies susitna and serene. It'll be a long time before I get a tank where I'll want a canister filter but this was something that had been bothering me.