Unrealistic Expectation of my Canister Filter or a problem?

[hellocatfish]

I'm just not sure what to think of my Rena XP3 filter performance. Originally I cut it some slack since I had left the intake hose a few inches too long and I was using another manufacturer's intake tubes. But now I've put things to rights and performance still isn't what I'm getting from running two HOB filters in tandem on another tank.

I'm seeing quite a bit of particulate floaties (look like small grains of beach sand, but are organic material of some kind--possibly uneaten Hikari micro foods-- in my 40 Gallon SeaClear 40 gallon. In my 29 gallon tank, running two HOB filters (AquaClear 200 and TopFin 30 modded to hold bio noodles) I have NO floaties at all, despite having fewer and less voracious feeders.

Foods given to both tanks are the same kinds each feeding. Feeding amounts are in proportion to the population and volume of the tanks.

Not sure exactly what the floaties really are--uneaten food would be a logical conclusion but I watch and to me it appears all the food is consumed very soon after I put it in. So it could be little bits and pieces of my real plants in the 40--which I do NOT have in the 29 gallon.

I'm wondering if the floating little bits of debris--which are DEFINITELY small enough to be sucked up into any filter, are a symptom of filter bypass. Or poor arrangement of inlet and outlet tubes? I have the outlet tube to the far left of the tank, inlet tube to the far right.

I thought I had everything set up within the parameters approved in the instruction manual. XP3 capacity should be able to handle a 40 gallon. I'm not sure if I'm dealing with anything to be concerned about or anything fixable, or if the filter just is not all that great. Water parameters are good on both tanks--no complaints about any of the filters to care for water chemistry. Just one filtration results in a tank that is way more clear of floating debris than the other.

Sorry if this post is not very articulate. There is a two year old wanting to go to the park screaming in my ear at the moment. I gotta run...

[Gerry]

I read on a forum (can't remember which one) that a member had the same problem and it was the baskets not fitted down properls was allowing bypass.

I have heard great reviews from fellow fishkeepers on the Rena xp3, though I don't think 1 filter will beat 2.

Hope this helps.

[apistomaster]

This is just my opinion but the two designs both have their pluses and minuses. I do not have any experience with the Rena canister filters and I read about the bypass problem caused by improperly seated media baskets. I only use the Eheim Clasic canister filters, models 2215 and 2217. The 2213 is too small for anything larger than 25 gallons, at least with the bioloads I impose.

I think a high volume HOB filter is pretty good about picking up large particles quickly. I don't think they have the same potential to "polish" water that canisters functioning properly do.

I seriously doubt that any of the HOB filters including the BioWheel(RBC) design filters come close to to the biological and fine mechanical filtering potential of a canister filter that is properly set up. Most all of a biological filter nitrification capacity is dependendent on the available substrate's surface area and the amount of substrate surface area of the sintered ceramic media is incredibly high, dwarfing that possible of any HOB aquarium filter.

It is a nuisance to have to use more than one filter on an aquarium but whenever one filter is intended to perform both mechanical and biological filteration there is always a compromise being made. I think most filters recommended tank sizes are based on very conservative bioloads. Not very close to bioloads aquarists actually impose.

That is why when someone asks advice on what filter they should use, and assuming they only want to run one filter, I recommend using the next or more higher capacity in a particular filter design they are contemplating. Very few aquarists are actually conservative in the bioload they impose on their systems.

Sometimes the best appoach is to use both, each assessed to be effective for a given sized aquarium.
The use of both can result in a synergistic effect that neither design acheives on it's own.

[hellocatfish]

Gerry and Larry,
Thank you both for your replies. I'll have to take a look and make sure the baskets are seated properly. I found to my dismay the last time I had opened up the filter to check it out that the baskets had indeed come askew. I could have sworn then I had put them in snug this time--doublechecking after last time, and if they are indeed askew again...I'm going to wonder how on earth that happened.

I see that Marineland has come up with a new type of canister design that is supposed to be "virtually" bypass free. It will be interesting to hear how good "virtually" actually is once more people own and review them. On the Petsmart site they are pricey and at this point if I were shopping all over again, I'd pony up that kind of money only for an Eheim.

When I'm finished with the quarantine period on my new stock I'm taking down the 29 gallon and putting one of the HOB's on my SeaClear to work in tandem with the canister. Additionally I still intend to put in the Hydro IV sponge filter and powerhead you recommended, Larry. I'll also be running a hang-in-tank UV sterilizer, but not all the time.

[MatsP]

One small point: Canister filters work best by taking water from the bottom of the tank. This in itself means that floating-on-the-surface particles will not be picked up very well.

--
Mats

[apistomaster]

There is much to be said for Eheim Classic filter design. By pass can only be possible should flow tunneling occur due to over due cleaning.

I have made it clear many times in the past that I recommend an inlet that draws from the bottom and incorporates a sponge pre-filter.

Also I prefer the fan-shaped return nozzle to a spray bar because it won't impede the flow rate as will most spray bar configurations.

For what purpose do you find the UV sterilizer useful in your setup and collection of fish?

[hellocatfish]

I had actually taken off the spraybar um...sometime last week I think. I couldn't have the spraybar AND have room for the HOB filter I plan to put in the accessory cutout on the rear of the SeaClear. So I'm running the default jet nozzle or whatever Rena calls their version of the return nozzle.

The UV sterilizer is not useful in any way, to me, to be quite honest as far as I know. Because I bought the SeaClear from PetSmart I got an e-mail discount and free shipping offer so I decided, what the heck, throw it in with the supplies I was ordering, as they didn't really have any other gear that I really wanted to get. I got it cheap and it has a sponge filter and adds current to the thank so that's a nice bonus.

I have a very stubborn algae & slimey goo-on-glass problem in the quarantine tank but none in the main tank, and I'm sure it would have shown up in the main tank by now if it was going to at all. I'm curious to see if the UV sterilizer will help with the algae problem. Also, I want to kill any free floating nasties that the new fish may be bringing in. Although more than likely, at this point given the comrades they lost, my survivors in the main tank are probably non-symptomatic carriers of "whatever" that are more of a threat to the new fish than the new fish would be to them.

All in all, though, it's not a technology I would have sought out if the opportunity to get one cheap and with bonus water movement capability hadn't presented itself. I certainly didn't want to get one I need to plumb into the canister. Unless I end up battling a seriously nasty pathogen somewhere down the line, it's a temporary or intermittent tool. I think the flow rate may be too high to do anything than knock out some algae, anyway. If I ever need UV to kill some Terminatory-type of pathogen, then I would probably need to pay more attention to specs. Maybe this one has the flow rate and wattage to do the job, maybe not. I didn't bother worrying about it, quite frankly.

I think it could in the long run be a liability, because I do want bacteria in my tank. Having had doctors bombard ME with antibiotics (due to my having an unreliable heart valve) if I so much as show up in their office with a sniffle and ending up with horrendous fungal or bacterial imbalances as a result, I'm not one for sterilizing the heck out of any environment. Also, more and more research on autoimmune problems and allergies indicate the immune system needs something to work on or it turns on itself in some nasty ways.

So, not sure I'll put it in the main tank at all. I installed it today in the quarantine tank and it's a big ugly chunk of hardware. Cories like playing in its current, though.

[wrasse]

Hi hellocatfish,

Larry makes a very good recommendation regarding a sponge pre-filter fitted to the intake pipe of your cannister. Ehiem produce a specially made one called 'Pre-filter', which is neat and easier to remove for cleaning than a sponge alone. It is purely a mechanical filter, allowing the biological filtration in the cannister to go undisturbed for a little longer. It also has a course sponge material, so it doesn't clog-up and affect flow.

[hellocatfish]

Hi Wrasse,
Oh yes, I have totally been in agreement since the beginning of planning my canister purchase that I would need a sponge prefilter. I just haven't been able to find one locally that I was sure would fit the Rena XP3. And hadn't had enough free time online to really shop very well.

I couldn't tell by looking at the info on the packaging, which in many cases on many aquarium accessories is barely present. So can anyone tell me if the prefilter sponge fittings are interchangeable among different brands or models?

Hmm...or maybe a better question would be anyone here who has a Rena XP3 can tell me which sponge pre filter they use?

I'd found many that say can be used with adaptors for major brands, then the ones that list the brands, don't list Rena. Maybe it's a known thing to everyone else that the prefilters fit on any canister but I'm new to this kind of filtration and some things confuse me that probably seem like a total "Duh--no brainer" shopping decision to everyone else.

I almost walked up to the PetSmart checkout line not long ago with what I thought was a sponge pre-filter only it turned out to be the part to one of those inside sponge filter types.

I really have only ever had experience with hang on back filters circa 1968-1975. They were see through big plastic boxes with little to them other than siphon tube, fluffy floss, and carbon. Not even a motor or impeller. I think my dad had to use something like a turkey baster bulb to get them started. I don't really remember.

Larry had made a specific recommendation to me exactly of what kind of internal sponge filter and powerhead to get. I had written THAT down and so far it's been out of stock at the LFS and PetPlace online, but I did recently find it online and will wait til I need to restock my next batch of supplies for online order and get it then so as to keep shipping fees as one expense.

I get some things from the LFS or the chains, some things from Petsmart online, and have been slowly branching out to buy from other companies I find are reputable and have good prices. What I hate about brick and mortar is by the time I can make a trip in to shop, they have the uncanny ability to be out of what I came in for...or worse, they moved it around and I overlook it as I shop as fast as I can with a 2 year old in tow. So I've been getting into the practice of stocking up via the internet. It's great--UPS just drops it on the front stoop. Yayy!

Oh update really of no interest to anyone but I took the UV filter out today. I had it running all night and that's probably not long enough to really matter, but it was adding too much movment to the quarantine tank and while the peppered cories liked that, panda babies couldn't get up for air without getting shot across the tank.

[hellocatfish]

Oh, almost forgot, my filter baskets were totally seated properly on the Rena XP3. Sooo...next tank...Eheim. And probably the Classic model. I don't feel as intimidated at the thought of working with one now. A little, but by the time I'm able to set up the second permanent tank, I should have even more experience and confidence.

It's not that I think the XP3's are duds, and I do believe the folks who say they get crystal clear filtration from theirs. It's just now this is the second Rena product I've had where I got it and after the fact learned there's considerable variability in quality and function of individual units. My air filter was a complete and utter dud, as was the case for many other folks who commented on them. Yet some people had great experience.

Of course, part of this variability, at least with the canisters, may be due to user competence. Maybe in a few months when I know more what the bleep I'm doing, I'll be totally raving about my crystal clear water.

Oh well, thanks to all who helped me on this topic.

[MatsP]

As to a suitable sponge (pre-)filter - surely you can cobble something up if you don't find the direct match? Just find one that is roughly right (preferrably with a SMALLER innside hole), and either stretch it out to fit, or use a sharp knife (scalpel or stanley for example) to cut it to fit.

--
Mats

[hellocatfish]

I take it you mean to work with a tube-shaped sponge & put it over my existing intake? I will go see if I can find one of those, then--I THINK I saw sponges like that at some point during my wanderings. The things I'd been looking at had the sponge on plastic intake tubes and didn't look like the sponges come off easily from the tubes.

As for cobbling something up...when you have made as many mistakes as I have and been bewildered by as many accessories as I have, it can make a person a little hesitant to experiment and risk something seemingly simple go kerflooey.

[hellocatfish]

Update: I took the filter apart a couple of days ago to make a schedule replacement of the micro-filtration pad. Interestingly, I found bacterial filtration evidence mainly on this pad, which is the last stage of filtration. The 4 foam filters at the beginning of the stage had evidently trapped NOTHING. Not even a speck of poop.

I think this filter is doing its job of biological filtration, if my readings are anything to go by. But as far as mechanical filtration, something is completely amiss. I'm going to head over to the Rena website and find out if maybe I have the media arranged in the wrong order. I did follow the instructions that came with the filter, but in some cases they do conflict with the instructions on the product boxes.

On Saturday I'd picked up a very cheap TopFin 40 hang-on-back filter from PetsMart. It's been a rousing success as far as mechanical filtration goes, and it added water movement that really got the fish all excited and playful. So, overall problem solved, but I'm still not confident at this point that the Rena is doing all it should be capable of doing.

[hfjacinto]

Hi Hellocatfish,

If you decide to get rid of the rena, I wanted to let you know that I am very happy with the eheim eco.

Its been 2 weeks and it is running very well. I see the intake and uptake tubes are starting to get a bacterial build up and the outflow is very consistent (same pressure, flow as when started).

[hellocatfish]

Thanks for the update hfjacinto. I appreciate it! You know, when I bought the Rena, it was very cheap from Petsmart and part of me was thinking, okay, well you get what you pay for. But I had read enough good reviews and comments to figure maybe it was well priced and would keep my tank going fine until I could bring my abilities and my budget up to Eheim level.

What I didn't count on is evidently, looking at a couple of Petsmart review postings made by people who got their new Renas about the same time I got mine--that there must be one batch that has a lot of duds in them...and mine is one of them.

Tonight I came home from a dinner out with my family and after I'm done unloading stuff from the car, I come in to find my husband fiddling with the tank. To my shock he was peeling a very dead danio off of the filter intake. Well I guess I saw that one coming--that fish had been looking bad for awhile now. I looked closer and my cories were all red-gilled. I didn't even have time to test the water, I just went into hyper water change mode. I knew what it meant anyway, that there was an ammonia or nitrite spike in this tank. How could that be? It's been cycled for weeks now and doing great. Well, just a couple of days ago I had taken out the micro filter pad and put in a new one, which is what you are supposed to do. I guess in my case that was a big mistake because evidently the bulk of my bacterial colony was on that one pad.

Because tonight I took the filter apart to try and figure out what the heck was going on in it. As far as I can see, the bio noodles look wayyy too pristine. I hadn't really examined them noodle by noodle before because I never wanted to disrupt the bacteria--my goal was always do whatever I had to do quickly and put the filter back together FAST. This time I looked and the white noodles were very white and the black filter stars--well, couldn't really tell, but they looked new to me.

It had been the microfiltration pad at the very top that had been full of bacteria. When I took it out I'd cut some off the pad to put in the hospital tank to cycle that tank.

Looking very closely at how the baskets are fitting together, I can see they don't produce a very tight seal, as some people have complained about some of the Rena's.

I spent a long time on hold to Petsmart tonight--never getting through, to see if I can return the Rena. One person reported in their review they could not. I still have the original box but not all of the packing material that came with it.

I tell you what, I don't care how confusing or complicated it is going to be for me, I am going to listen to Larry and get the flipping Eheim Classic. I will figure it out. If I can't, well my husband is an engineer and my daughter is only two and a robotics fanatic who once put together a doll stand that I couldn't make heads or tails of. Between the 3 of us, somebody should be able to put the blasted Eheim together and teach me how to maintain it!

I'm going to take back some other stuff I bought from PetsMart--like the UV sterilizer replacement bulb. I am keeping the UV sterilizer itself for occasional use, as it works pretty good blasting algae to bits and it's the kind you can take out and store away when you're not using it. I'll TRY to return the Rena. If it still turns out I can't return the Rena and can't afford to get the Classic, then I'll get the Ecco and I think that will work out.

But I'd rather have the Classic because at this point I don't trust media baskets anymore.

[Marc van Arc]

But I'd rather have the Classic because at this point I don't trust media baskets anymore.

Which is of course absolutely unnecessary. You may choose any filter type you like, but there's no reason to distrust Eheim media baskets

[hellocatfish]

Yes, that is true and you are right & I appreciate the humorous way you pointed out the lack of logic in my post. But I'm very grumpy about my filter follies so I'm just venting. I was so happy to have had a smoothly running and cycled tank, after the fish in it had been through so much. I really blew my temper when I saw that just one dead fish could cause enough of a spike to make the cories' gills look irritated.

The Rena Filstars have been in the filter since its inception--if they didn't have enough bacteria in there by now to combat one lousy dead fish's waste, and all the bacteria doing the work of keeping my tank readings good had actually been colonized in the micro-filtration pad that is supposed to be replaced regularly, whoa, that's just messed up. I mean, I have this canister just filled with noodles. Yes, some are recent additions but two of the media baskets were filled with noodles/stars that should at least have had as much, if not more beneficial bacteria living in them as the micro-filtration pad apparently had. Those noodles and stars predate the installation of the last microfilration pad by weeks.

My options are limited. My husband is NOT letting me get a new filter of any kind, as it's not in the budget since one of our cats got sick and needed a lot of tests for a stomach problem that may turn out to be cancer--tests are pending.

I think I will try ordering a couple of baskets from Rena and see if these replacements provide a better more snug fit. The replacement baskets are within our budget.

My husband said the next time I shut down the filter he will take a look to see if he can rig something to make it work better.

[hfjacinto]

Hellocatfish,

I see you are in the mid-atlantic which could be NJ to Virginia, if you are close to NJ, I could give you an aquaclear 300. It has a new motor and intake tube. I was going to move it to the 10 gallon in the office but its too big. So its now sitting in the garage. Its yours if you want it.

I am in Union, NJ. Like the famous question "What exit?" either 140 off of the Parkway or 50B off of Route 78.

[Marc van Arc]

Yes, that is true and you are right & I appreciate the humorous way you pointed out the lack of logic in my post. But I'm very grumpy about my filter follies so I'm just venting.

Just to make things clear: I certainly wasn't mocking you. The remark was meant to cheer you up a little.
Fwiw: I couldn't find anything illogical in your post.

[PsYcHoTiC_MaDmAn]

I'm going to have to try a few other filter brands, personally from specs allone i've bought fluvals rather than rena (their also cheaper), and left eheims allone because of the cost. I've never had an issue with waste bypassing the prefilter sponges, and i keep the baskets for prefilter (crushed coral in this case),filterwool and ceramic noodles. its worked a treat for me

I've allways over filtered my tanks (fluval 405 & 4+(int) on a 140l tank)and never really had a problem with removal of gunk. however i've installed a surface skimmer on several of my tanks due to the bio film, so its possible to remove water from top and bottom of the tank via canister.

[hellocatfish]

Yes, that is true and you are right & I appreciate the humorous way you pointed out the lack of logic in my post. But I'm very grumpy about my filter follies so I'm just venting.

Just to make things clear: I certainly wasn't mocking you. The remark was meant to cheer you up a little.
Fwiw: I couldn't find anything illogical in your post.

Yep, I know that. I was saying I appreciate how you were being humorous. You did make me smile. I meant my post literally, I was not being sarcastic. I try not to ever use sarcasm on an international forum because language & cultural differences can cloud humorous intentions. So for example if I had felt mocked, I would have said "I do NOT appreciate..." Sorry if I made you feel like I was snapping back at you or acting defensive. No--I was laughing at myself WITH you. Because I was definitely feeling cranky about my filter problems. It's like I can't catch a break with my tanks. Even when I'm not doing something totally stupid, I get that kind of bad luck with the gear. Oh well, maybe it is stupid to NOT get an Eheim when everyone whom I respect here vouched for them so emphatically!

And you are being very kind...my post was totally illogical. I think the term is non-sequiter...???? Meaning I came up with a reason to shun ALL media baskets that does not necessarily follow from the particular problem I encountered. I bet if anyone were to do an actual study, they would NOT find a higher failure rate among filters that use media baskets.

So I was being a silly-billy!

[hellocatfish]

Hellocatfish,

I see you are in the mid-atlantic which could be NJ to Virginia, if you are close to NJ, I could give you an aquaclear 300. It has a new motor and intake tube. I was going to move it to the 10 gallon in the office but its too big. So its now sitting in the garage. Its yours if you want it.

I am in Union, NJ. Like the famous question "What exit?" either 140 off of the Parkway or 50B off of Route 78.

I had made a reply to your post--it doesn't show up, but it may, so I will not repeat everything I wrote in case it does show up.

But just in case it doesn't--thank you so very much not only for your kind offer but for your consideration of my predicament. I'm actually about 3 hours away from NJ. I'm not sure where Union is...I've only been to NJ a handful of times so I don't have much of a grasp of where anything is. I only even know it's 3 hours away because my husband sometimes has to travel to a field office in NJ.

I think I have my filter situation temporarily remedied for now. A couple of weeks ago I did add a TopFin 40 to the tank. TopFin40's are lousy filters if you use them as your sole filtration and "as is". But I mod them and love them the way I have them tricked out.

[MatsP]

I think I will try ordering a couple of baskets from Rena and see if these replacements provide a better more snug fit. The replacement baskets are within our budget.

Have you considered contacting Rena themselves about the problem (their US importer would be the recommended point of contact)? I think they would like to know about your disappointment in their product. If you explain your problam clearly (and I know you can do that, if you make an effort), I think they will make some effort to help you.

My husband said the next time I shut down the filter he will take a look to see if he can rig something to make it work better.

Surely, such rigging shouldn't be necessary!

--
Mats

[hellocatfish]

I have wanted some time to shake this issue out on my own and be dead sure it wasn't user error or an easy fix with a 99-cent replacement part. Just seeing how they have resolved other customer problems--basically suggesting getting the replacement parts or buying a whole new motor after only 3 years run-time, I wasn't too eager to waste my time composing a good correspondence to get THAT kind of answer. Aside from loads of other difficulties I'm juggling these days, I just put in a 16 hour stint at the hospital yesterday with my dad in there for cancer surgery and at this point I have more money (for new baskets anyway) to throw at the problem than I do time or energy or coherence. I'm just too pooped to resolve this properly for now. But I agree, the RIGHT way to go about it would be to do what you suggest. And when I can find it in me to be patient and logical enough to do so, I will. You're right--I CAN do it. I have held some customer service oriented jobs and understand how to work both sides of the equation.

At least the end-result is okay for now. Whatever tinkering I did the last time I opened up the filter has been sufficient to get the readings back to where they should be. That doesn't mean the filter is working like it should. Maybe the bacteria are once again colonizing on only the last-stage micro filtration pads. Whatever...at this point I don't care as long as there are good bacteria in there SOMEWHERE doing their jobs.

I won't know until I open it up again if the problem has truly been corrected. I can see through the canister somewhat and it APPEARS the baskets are seated tightly. Only a look at the first 3 filter pads will tell the truth of the matter. But I'm not going to do ANYTHING to disrupt the workings of the tank now, because I don't have time or energy to correct any problems that might arise if I disrupt whatever filtering magic I've got working in there for now.

[hellocatfish]

Okay, I'm sure now...it's a lemon. Eheim Ecco 2236 on order from PetSmart. The Rena will be on emergency reserve in the basement or the garage and its noodles will be put in the Eheim. Whew...glad that's resolved. Isn't that as an exciting news announcement as Britney Spears shaving her head?

[MatsP]

Okay, I'm sure now...it's a lemon. Eheim Ecco 2236 on order from PetSmart. The Rena will be on emergency reserve in the basement or the garage and its noodles will be put in the Eheim.

You really should send it back to Rena - if they don't do good product, they should have it back (and you should get the money you spent on it back).

Whew...glad that's resolved. Isn't that as an exciting news announcement as Britney Spears shaving her head?

As far as I'm concerned, she can do whatever she likes with her hair...

I'm much more interested in your filter troubles...

--
Mats

[hellocatfish]

I've just got too much going on and it's just not something I want to bother with right now. I've got too much to juggle and correspond about--medical insurers stuff, wedding related stuff, baby-shower related stuff, birthday and anniversary parties to help coordinate. Our sick cat recently passed away and now the dog is having issues--not sure if the petfood recall in the US is related or not--the recall expands every time I check and it's hard to be sure. I thought for certain my cat's illness was completely unrelated. But the dog...who knows. Vet visits are forthcoming, I'm sure.

If I ever thought quitting my day job and being a housewife would be boring or uneventful, I was seriously misinformed!

I'm getting the Eheim and it's being delivered tomorrow. Hopefully that will work out great for the tank and be one less thing to worry about around here.

[hellocatfish]

Woohoo...the Ecco is awesome! However, I did have to take out the Ehfi Substrat Pro. The bags it came in were kind of mildewy and I had a cloudy tank when I first ran the filter...even though I'd rinsed the substrat really thoroughly.

I opened up the canister and took out all but a few grains of the stuff and put in panels of floss instead and did a water change and all is nice now. I have all of the noodles and bio stars from the Rena in place so at least I didn't have to start from scratch in establishing a bio filter.

I'm still going to analyze what went wrong with the Rena...when I get the chance.

[azfisher]

I have been reading through these posts and am now a little concerned with Rena cannisters. I bought an XP3 a year ago and it is still sitting in the box as it was meant for emergencies. FYI, I have 7 tanks that are up and running all the time (2 - 125's. l - 80, 3 - 50 gal and one 40 gal.) All tanks have at least one Fluval 304 on them, but the prices on Fluval has gotten ridiculous. Even the on-hand stuff like pre-filter foam, etc. is foolish, let alone trying to have a ceramic shaft and shut-off valve assembly on hand at all times. I love my fish dearly, but also like to eat, so upgrading on filtration will have to advance slowly.
HOWEVER, I will admit to having three good old Aqua-clear 500 filters on one of the 125 gal tanks and I have been very pleased with the results. Obviously this much water movement is only for fish that can handle or even prefer a lot of current and the constant surface flow keeps scum away quite nicely.
Our water quality here in Arizona is simply horrid, so I must rely on both bio and chemical filtration. I use ChemiPure media on and off as necessay and lots of Amazon Rain additive. One thought - when one uses the Aquaclear 500 filter, do not let your water level come too close to the return flow from the box - one of my Gold Nuggets figured out how much nicer it was inside the filter box and I had to rig up a barrier to keep him out!
On my Discus tanks (which also contain S.A. suckermouth catfish that can tolerate the higher temps) I must be very careful on water current. The Discs have adapted nicely to a Fluval 204 and a 304 at opposite ends of the tank (80 gallon tall) with mega-diffusers. Just some random thoughts. I do admit to a pretty strict regimine of water changes and gravel vaccuming and basically the fish that are long-term residents have become very used to my fooling around. It is strange to have the Black Ghost and one large pleco nibbling on your arm while servicing a tank. Any thoughts on filteration experiences are welcome!

[GreenSynoMan]

This filter debate is very interesting to me. I have never used canister filters. My 10 gallon is filtered with a Marineland Penguin Mini; my 60 gallons are filtered with Marineland Emperor 400s, and my 80 gallon tall is filtered with an Emperor 280 and an Emperor 400. I have never had any issues with fish dying throwing my ammonia/nitrite/nitrate levels off, unless many fish died at once. Then again, I'm not checking my levels often, and mainly going by whether or not I lose fish as an indicator.