Flow Rate Vs Contact Time

[banana]

This has probably been covered before but i searched and couldnt find anything

What is the optimum flow rate to have in a sump filter? The tank's 300l and the sump is about 100.

The sump contains about 4-5 litres of bio-media(bio-balls,eheim substrate,matrix) and a course,medium and fine filter pads.

Is the faster the flow the better or is the amount of contact time with the media more important?

 

[ellena]

Hmmm, that's not something I'd thought of before. Interested to hear answers to this...

 

[chrisbassist]

Since the bacteria do their job pretty quickly, they don't need much in the way of contact time. So flow rate is more important.

It also sounds like you have it set up as a large external filter, rather than using the sump like you would on a marine setup. Which means I'd say follow the same rules as external filters and aim for 5x flow rate

 

[banana]

Its a fresh water tank

I know,I know but my friend gave me the tank and it came with a sump and i already had freshwater in my other tank so i just transported everything to the bigger tank.

It seems to do a #40## good job at filtering though

Also 5x flowrate seems waaay to slow, the water barely seeps down the overflow and barely manages to spin the outlet thing in the sump so i added another pumpn which increased it to 18x! and the whole system runs smoothly with moderate to fast water flow into and out of the sump.

Is 18x too much flow for the filter?

 

[fatheadminnow]

There is no such thing as too much flow rate. One of my tanks has perfect water parameters at less then 1x turn over in an hour... and some of my other tanks are pushing 10x+ turn over rate an hour.

Whatever you think is okay will be find because the bacteria will very easily be able to adapt to any flow rate.

-FHM

 

[banana]

thanks