Filter Placement In Tank

It is usual to have the tube that takes water out on the opposite side from the tube that returns the water. The argument is that if they are both on the same side a good proportion of the returning water gets pulled straight into the out take tube.

Also, does the placement have any influence on the circulation? and how much surface movement is required for gas exchange to take place?

Hi Littlefish,

The placement of the inlet and outlet pipes will affect the circulation and I agree with Sue on this. Regarding circulation, I have come to the conclusion that some external filters are inferior to internal filters in this respect. So, I supplement my external filter with an internal circulation unit.

As regards how much surface movement is required to ensure adequate gas exchange, this is important particularly when injecting CO2 for the live plants. I measure dissolved oxygen using the JBL O2 Test Kit (the new version) and dissolved CO2 using a drop checker plus the JBL CO2 Direct Test Kit. Both these gases need to be measured at different times of day.

JPC