Hi all,
I've always used big externals, favouring Eheim, I dare say others have caught up in the last 15 years
I still think the Eheim Classics are the best external filters, but I'd definitely keep and use the trickle filter.
Wet and dry trickle filters are probably the most efficient filters in terms bio-filtration, and their ability to fully oxygenate the water is absolutely ideal for rheophilic fish like Plecs.
Why Trickle filters are so good.
Because you have a thin film of water moving over the media in a trickle filter, it has a huge gas exchange surface (CO2 out, O2 in) and this means that the filter has the capability to convert large amounts of ammonia to nitrite and nitrate (You need 2 x O2 for every molecule of NH3 converted).
NH3 + CO2 + 1.5 O2 → NO2- + CO2 + 0.5 O2 → NO3-
Often what limits biological filtration capacity is amount of oxygen (O2) reaching the media. This is a
particular problem with canister filters, when the filter is used to both syphon organic waste out of the tank and to biologically filter the water, as soon as flow speed and volume slackens biological filtration is compromised. Often the capacity of the filter is increased by removing some media from it, and replacing fine sponges etc with media like ceramic rings, which are difficult to clog.
I'm not familiar with this make of trickle filter, but I'd put a coarse sponge in an accessible place where you can clean it fairly frequently (pre-filter or protein skimmer box (you don't need the skimmer)) and then use alfagrog as my filter material in the filter tower (or the bio-balls if they came with the filter).
They can only give you nitrate if there is waste to convert...The reason you seem to have more N03 is because this type of filters are very aerobic with very little anaerobic bacteria to use up the nitrate's
As DMac says it is their huge bio-filtration capacity that can lead to NO3 building up, NO3 can only be removed in 3 ways.
- By water changes
- By the anaerobic bacterial conversion to N2 gas which out gases to the atmosphere.
- or by being assimilated by plants.
Marine aquarists usually don't have any plants and need to keep nitrogen (and the other macronutrients) at very low levels. They often also need to keep water changes to a minimum, unless they have a ready source of clean sea water. To do this they use de-nitrifying coils, Jaubert plenums or deep mud filtration, all of which aim to out gas their N2 from an anaerobic environment. These are all quite difficult to run effectively.
In the fresh water aquarium it is much easier not to have any anaerobic conversion of NO3, and use plants and water changes to keep NO3 levels low.
There are more details here: <
http://plecoplanet.com/?page_id=829>
cheers Darrel