Sorry if I renaswer any questions, I tried to start off where everyone left off, or simply emphasize/add to a few points, but I have a horrible memory sometimes, lol.
Bioload = the amount of biological waste that is being put into your system. More fish = more waste = more bioload.
Some species of fish produce more waste than others thus put more bioload on your tank. Anything decaying in your tank adds bioload (excess food, sick plants, fish poop, etc.). The higher the bioload in your tank the more filtration and water changes are needed.
fx5= Fluval Fx5. A model of canister filter with a large capacity and flow rate, useful for large tanks.
For this size tank, is a canister or powerfilter more appropriate?
You can use either or a combination of both.
Advantages of canister filters:
Can be hidden under tank. Intake tube and output can be positioned where you want it. Can hold large amounts of biological media. (Biological media are the objects that hold your biological bacteria, such as ceramic rings or sponges. There are several types of biological media, some more efficient than others)
Disadvantages:
Can seem complicated to break down and clean at first. More expensive. Must be broken down to clean and replace mechanical filtration cartridges.
Advantages of HOB power filters:
Mechanical filtration catridges can be easily cleaned or replaced. Generally easy to set up. Generally easy to break down and clean.
Disadvantages:
Takes up lots of room on back of tank. May be noisier (Depends a lot on brand/model).
The best filtration option for the average tank is a combination of canisters and power filters, in my opinion. If you want a heavily planted tank canisters themselves are the best option. On smaller tanks power filters by themselves are generally the cheapest and easiest option.
I have read about a few of them at aquariumguys.com, and the best they offer are rated at 90-100 gallons.
You'll want to completely ignore what size tank the filters are rated for. Different companies rate their filters differently, so while one filter that is
rated for 100 gallons may actually support that size tank with a full fish load, most likely it will only support a tank half that size. Some companies are completely illogical with their filters ratings which seem to be decided by a magic 8 ball or something. Most companies are going to overrate their products.
What you want to pay attention to is the GPH. This tells you how many gallons per hour the filter is pumping. Usually they are rated WITHOUT media such as filter pads, biological and chemical media, so you must keep this in mind. A filter that is rated at 350GPH will most likely not flow that much when completely set up. Some filters tell you what the average GPH with and without media is, so pay close attention. Companies that don't list their GPH anywhere should generally be avoided. All the better brands will have it listed conveniently on the box or their website.
Considering that most people here tend to have more filtration per gallon than the filtration supposedly supports, how many of each should I be thinking about getting?
I agree on this point:
Turn over rates are also nothing more than a apporximate gauge and are ALWAYS lower than stated but it's still a useful guide. In general try for number thats at least 4 times the aquarium capacity and less than 10 times.
(some of us with monster fish go over this mark but you have to be careful and know what your doing...besides in most cases anything over 8x is a waste of equipment and power.)
I would suggest going with a combination of two or more filters though. On a larger tank it is DETRIMENTAL that you have redundancy so in the case of a filter failure there is always another filter running.
Aquariumguys.com basically called the diatom filter the best filter, but warned it was dangerous to the lungs and they recommended that it only be used to clear the tank up then switiching to another filter. Would a diatom filter running full time be the best option available, lung problems aside?
You don't need a diatom filter right now, so I would set that thought aside. Diatom filters are very specific in their uses and aren't needed for the general aquarist. They are not good all around filters.
I have seen Fluval5 mentioned as well. Are Fluvals and Eheims in the same category, and if so, which one would be better for what I am planning above?
Eheims are a higher end canister filter whereas Fluvals are one of the cheaper canisters, and while some people swear by them I don't. Although I'll admit they can work just fine with proper maintanance and some know how I wouldn't recommend them to someone that is new to filtration in general. The Fluval FX5's are apparently good filters but may be more than you need right now. IMO Eheims are overpriced, though they work well.
Rather, I would recommend a Rena Filstar xp3 because they seem to be reliable and they should be easy to break down for most anyone. Cascades (by Penn Plax) seem to be ok even for the relatively cheap price, but stay away from any other products made by this company.
Of course a lot of us disagree on our brand loyalties and such but this should be a good general outline.
One brand I will recommend you completely stay away from right now is Magnum canisters. Not because they are bad filters but they are horribly annoying to set up, break down and maintain.
