There are two kinds of mechanical filtering systems - using pressure and one does not have pressure. The pressurized systems have some kind of canister. The non pressurized filtering systems allow the water to trickle through or around the filtering media. Which one is most effective? most dependable? the pressurized systems seem to be more expensive.
You mean like a HOB (Hang on Back) filter, like say, an AquaClear?
It really all boils down to personal preference. There are many designs that work so well. I'd still be using my AC500 on my 100gal if I had the clearance behind the tank. As it was, it sat on the front of the tank until I plumbed my canisters.
In a HOB the water is pumped through a tube and allowed to overflow back into the tank. In a canister the water is pulled out of the tank and pushed back in by one pump. A Wet/Dry or Sump system pumps water into the tank and the tank uses an overflow system to refill the sump. Canisters are generally larger and have more room for filter media than HOB, and Sump or Wet/Dry systems are even bigger and can be whatever you can imagine. Canisters tend to cost more than HOB filters, and Sumps can cost as much or as little as you want to spend, depending on how much DIY you are interested in. Efficiency is generally a question of how much water can bypass the media. Generally speaking the order of effectiveness is the same as the order of cost with HOB being least effective, Canisters being more effective and Wet/Dry being most effective if it is designed properly. Dependability has everything to do with brand, and little to do with type of filter. Quality components results in dependable equipment. Personally, I swear by Hagen and AquaClear for Filters and Powerheads. BTW, all of these depend upon gravity as a critical mover of water, and none of them are really "pressurized". Canisters are sealed, but I don't think there is any significant pressure inside. If you sealed the top of a sump you could use a syphon instead of an overflow and have your own homemade canister filter.
Because I'm hardheaded, stubborn and relativley skeptical I ended up using a huge Hozelock pond filter for my 120 gallon. First off I got it for a steal. Second, I was going to go with the Ehiem because I read over and over that it was the one to have and that a lot of folks are very pleased with them. So if the pond thing doesnt work out I'll get the Ehiem immediatley. I'll be gaining more than I'm losing.
Right now the Hossie is doing a spectacular job. The water chem is holding nicley and I will start stocking soon (slowly). I did make a mod on it where I was able to put some charcoal in the bottom under the foams. That made a difference right away.
Like the guys said above it's a matter of what you want to do, space you have, and money you want to spend. Do your research.
ok well i kinda have a more specific question...well sorta...lol i am currently using two 330 gph HOB filters on each of my 55 gallon tanks and i am seriously considering changing over to canister filters so as to increase my media choices(wanting to give seachem purigen a try). my question is if 1 350 gph canister will do the same job as 2 of the 330gph hob's do? i ask this because i really dont want to spend the cash to put 2 canister filters on every tank. hopefully someone can help out here btw the brands on these are as follows: the HOB's are aquatech 30-60, and the canister is the cascade 1500. thnx for any tips and advice you can give.
I'm all about the canister filters. Their 'cost to run' is cheaper long term, they do a better job of filtration than a HOB, they can be hidden behind the tank for a cleaner look, they are much quieter, easier to clean, you can alter your flow options (spraybar, etc). How much better do they have to be?
Cichlidquy - I use a rena xp3 on my 55, which houses an oscar and a pleco. Those are 2 of the dirtiest fish you can imagine, and the rena does a great job. I do keep a sponge filter in there too, for polishing. The sponge is powered by a small air pump.
The only problem I have with my xp3 is that it puts heat in the water...I'm sure the lighting doesn't help either. I don't even run a heater in my tank and it stays at 79-80. The AC in the room keeps the ambient temp at 74-76.
