01-08-2012, 01:43 PM
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Ah...filtration, one of my favorite subjects. There is a current myth that filter water flow must be 4-10 times the size of the tank in GPH. Good filtration is not about how fast or how much water is pushed through a filter, but rather how well we filter the water. In fact, water flowing more slowly through very fine media filters the water better than blasting through coarser media. Running all of the tank water through a good filter 2-4 times per hour should be more than enough if we're doing it right. As a matter of fact, some folks with heavily planted tanks use simple bubble up sponge filters that process very low GPH since plants help filter the water. Detritus can be allowed to decay in the upper layers of the substrate to help feed the plants or can be removed with a gravel siphon hover above the substrate surface.
Some folks seem to thing they have to have all kinds of water flow to move detritus into the filter inlet. (I hear all the time about folks adding power heads in addition to their filters).
It's almost impossible to do this and many of our fish don't appreciate these high flow rates in the tank. It's far better to let mulm collect naturally on top of the substrate and remove weekly with the water change - or better still, if it's a planted tank, just let it decay and help feed the plants.
It takes 4-8 weeks to cycle a tank unless significant biology is bio-seeded into the tank (and about 6 months before the tank is considered 'established').
For instance, if we took a filter or filter media and some substrate from an established tank to start a new tank, we could add some stock right away as there would be enough biology to handle the bio-load.
Also, if the tank is medium-heavily planted, cycling is not required as the plants will process the ammonia directly.