reid@decwrl.dec.com (Brian Reid) (12/31/87)
As far as I can tell, other people are also enjoying reading the answers to the various questions that I am asking, so unless I start getting "be quiet" messages, I'd like to ask a few more. It's really very informative to read different peoples' points of view on these issues. I want to learn more about wet/dry type of filters. From what I have learned by reading advertisements in FAMA, and from an occasional veiled reference in this newsgroup, a wet/dry filter is an external filter that is used in the following way: 1. You pump water out of the aquarium. Sometimes you run this through a simple mechanical prefilter so that big junk won't get into the next phase. 2. You sprinkle this water over some filtration medium which is in a big chamber. Evidently you sprinkle it pretty slowly, so that the water just trickles down through the filter medium. 3. The water flows out of the bottom of the filtration chamber into another part of the filter, where it gets other things done to it, such as protein skimming or activated carbon or whatever. 4. The water is pumped back into the tank. My questions are these: 1. Why does the water have to be sprinkled slowly over the filtration medium? Why can't you just flood it the way you would flood a cannister filter or a gravel bed? There must be some reason, or else people wouldn't go to the tremendous expense of building the trickle mechanism. 2. Why does the protein skimming come after the sprinkling? It seems to me that it would be better to get as much junk as possible out of the water before sprinkling it onto the filter medium, in order to minimize the amount of clogging and to reduce the number of times it has to be cleaned. 3. Why do these things cost many hundreds of dollars? They don't look like they are even as complicated as an ordinary cannister filter, except that they have some custom Plexiglas in them. Plexiglas can't be that expensive. There must be some piece of the filter that I haven't figured out yet, whose presence would enable the manufacturer to charge $500 for it, as many do. 4. As long as you're going to spend that kind of money buying a filter or that kind of time building it, why not make it do everything? Why not add a filter stages that has activated charcoal, sort of the way the AquaClear power filters do it, so that when the water is pumped back into the tank it is completely ready. Is it because you want to be able to turn some of the filtration on and off, e.g. turning off the charcoal when you are medicating? Brian Reid