Systems - The Structure
Fluidized Bed Filtration
Written by Wednesday, 14 April 1999 17:00
It's said this is the latest fashion in filter technology; its main highlight is its capability to eliminate (be reduction) an enormous amount of nitrates (NO3) while absolutely no mechalical filtration of any kind is performed. Keep this in mind when You chose such a filter. The idea that's behind this filter is absolutely simple: a water flow moves "sand" inside the pipe (number 4 in drawing), amongst floating sand (after a settling period long up to 40 days!) nitrifying bacteria (nitrosomonas and nitrobacter) will settle "feeding" on ammonia and nitrites, while anaerobic bacteria will take care of nitrates. Any kind of matter (wastes, decaying food, leaves and so on) floating in tank will, highly, reduce filter's performance (mostly if once entered the filter they'll result too big to get out!!!) You know how it is when keeping Mbunas ... they dig, dig, dig, dig ... dig all day long!!!
Its outstanding oxidizing / reducing performance fascinated me when I faced the duty of setting up one, more, tank for my beloved M'bunas (wild caught specimens, got at Lake Malawi, back in 1997, during a safari), then as soon as I decided to use this filter (mostly for the sake of curiosity and wishing to test this new technology) I had to face the only, and real, problem of those filters: debris, mostly because of M'bunas digging attitude. That's why I decided to use a canister filter, as a pre-filter unit, before the water flow reaches the "Fluidized Bed Filter" unit (see drawing) and also an internal, separate, filter performing only a mechanical action (flow: 600 lt/h - 160 gals/h; not pictured) then the problem was choosing a pump, of correct flow and power, suitable for this use. Those filters, generally, do better with slightly overpowered pumps (moving water through all the filter system is quite an effort) and thus can result slightly noisy. The rest has been a "plumbing-game" choosing pipes, connections, taps of correct size and connecting them all in a suitable way.
Drawing, Pictures and following notes, should, I hope, explain, in further details, how the filter has been built up.That's why I decided to use a canister filter, as a pre-filter unit, before the water flow reaches the "Fluidized Bed Filter" unit (see drawing) and also an internal, separate, filter performing only a mechanical action (flow: 600 lt/h - 160 gals/h; not pictured) then the problem was choosing a pump, of correct flow and power, suitable for this use. Those filters, generally, do better with slightly overpowered pumps (moving water through all the filter system is quite an effort) and thus can result slightly noisy. The rest has been a "plumbing-game" choosing pipes, connections, taps of correct size and connecting them all in a suitable way. Drawing, Pictures and following notes, should (I DO hope!) explain, in further details, how the filter has been built up.
- Is, simply, the tank on his stand (mine is 360 lt/100 gals).
- Is the canister filter (has a pump of 600 lt/h - 160 gals/h in flow. BTW tried also a 840 lt/h - 220 gals/h; bit too noisy). This filter alone is suitable for filters up to 250 lt - 66 gals/h..
- Is, basically, the "Fluidized Bed Filter" stand.
- Is the "Fluidized Bed Filter" unit, suitable for tanks up to 1200 lt - 300 gals (alone! Both filter reach a flow way over tank's need).
- Is the intake pipe (has two taps; one safety tap on the pipe while the other "open/closes" the cantister filter flow.
- Is the outlet pipe to "Fluidized Bed Filter" and to tank (redirects a possible overflow)
- Is the outlet pipe from "Fluidized Bed Filter" to tank (main flow).
- Is the safety tap on inlet pipe (see point 5).
- Outlet tap of canister filter.
- It's the "T" switch direct possible overflow directly to tank (NOT passing trough "Fluidized" unit)
- Is the safety tap on inlet pipe of "Fluidized" unit.
- Is the safety tap on outlet pipe of "Fluidized" unit.
- It's the flow control valve of "Fluidized" unit (increse/decrease) water flow to tank
- Is the safety tap on outlet pipe of "Fluidized" unit.
- Power supply cord (mine is 200 V: 50 Hz).
Thanks are due to Vladimir Potabenko for spotting some mistakes in the original article.
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