Join Date: Jul 2010
Location: Outside Philadelphia, PA
Trickle filters or wet/dry have their place today. I would use one only on specific types of systems. In SW I'd use it on a fish only system where I could not use much live rock in the tank. In FW I'd use one on a system where I couldn't have live plants, such as a tank for large fish that dig.
Trickle filters on most other systems tend to be not needed or even counter productive. In a SW reef system the usually do turn out to be nitrate factories. This is because they are very good at the reduction of ammonia to nitrite to nitrate. Often they are too good at this, resulting in high nitrate readings. This is a big problem on a SW reef system. This is also why you see a lot of SW people remove the bio-media from a trickle filter.
On a FW planted system, the nitrates can actually be an advantage. Nitrate is a source of food for a lot of plants. However, trickle filters are also very good at gas exchange, getting C02 out and O2 into the water. This can be a problem for planted systems because you need CO2 for plant growth. You can resolve the problem by adding CO2 to the system. Typically you'd want a pressurized CO2 system, so you can keep up with the CO2 being removed by the trickle filter.
That about sums up the good and the bad about using trickle filters. As you can see, most of what you have read it true in one form or another, but you also need to consider the kind of tank your running.
The bottom line is that you can use a trickle filter on a FW planted tank, as long as you keep up with the CO2 demands of the plants. However, if I had a choice in the matter, I'd op for one or more canister filters, depending on the size of the tank. They are a lot less noisy, and a lot less prone to floods.