filtration

[clownloachfan]

lately i have been looking at filters for a possible upgrade. I currently have a an emperor 270 withch is recomended for up to 50 gallons with a flow of 270gph. some canister filters out there are rated for the about same size tanks at 110gph. thats a big difference in specs. why?

[Diana]

Here is a really good write up on filters.
http://www.seachem.com/Library/Articles ... ration.pdf

Filters provide 2 things for an aquarium. Water movement and filtration.

I aim for 10 times the tank volume in water movement, so a 50 gallon tank would get a filter rated at 500 gallons per hour.
I am sure the filters are not really providing quite that much flow.
The flow does not have to be all from filters, I have some tanks with rather small filters, but a large power head.

Filters with thin media (replaceable cartridges) are poor filters. They allow too much debris to return to the tank. Filters with thicker media that you clean and reuse are much better filters.

I have an old Penguin 350 that I use on a 40 gallon tank, and several 170s that I use on 10 gallon tanks.