Zero bypass filters

apastuszak said:
The Fluval doesn't have any foam or floss in the media baskets. It has 4 rectangular foam pads that run the length of the filter from top to bottom and is inserted perpendicular to the media baskets.
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That actually started with the "04" series of Fluval canisters. The "00-03" series of Fluval canisters had foam sponges inside the media baskets and a round canister. The "02" series used a single large sponge on the top. The "03" series split it into two sponges.

I think the whole issue of filter bypass is a red herring. If filters had zero bypass they would clog up so quickly as to be nearly useless. When the truth is that some bypass occurs with every filter. Water will channel and find a path of least resistance all the time.

In reality, our aquariums are recirculating systems and the water (however you want to subset it (milliliter, molecule, etc...) will pass through the filter multiple times per day so that at least at some point the subset of water will come into contact with filter media through the course of a day.

The filter media doesn't have to touch the water subset every pass to maintain water quality.

Andy
 
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Did some more research and found out where the "bypass" problem occurs.

The media basket cover does not form a tight seal against the bottom of the motor, allowing water to sneak past the media baskets and make it out the filter. The gap supposedly between the basket lid and motor is about 1/4" (6 mm).

I read a thread where someone took a magic eraser and cut a hole in it, placed it between the media basket cover and closed the lid on, and is claiming their tank is a lot cleaner. Doing this however seems make it WAY HARDER to get the air out of the canister when you clean the filter.

I'm not sure what the the forum policy is to linking to other forums, so I don't want to post a link to the thread.

The used 305 I just got, has a media cover that is not completely flat. The part with the opening is actually sunken in, making the whole lid somewhat concave. This would cause an even larger gap.

I need to clean the 305 on my tank today anyway, so I think I'll grab a magic eraser and give it a try.
 
Ran out at lunch and grabbed a magic eraser and started cutting. An X-Acto goes tought it like a hot knife through butter.

Here's the thickness of the thing:

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And it squeezes down to this when I pinch it with my fingers:

5EsivCA.jpg


I squeezes it on top of the basket lid and turned it make a cut and know how to cut it out. Then I used an X-Acto to cut a hole through it:

HuwV9c4.jpg


And here's what it looks like on the lid:

GFeUbzt.jpg


I'll be testing it out in about 2 hours.

I'm not sure how I'll know it's working any better, since the system is sealed when it's running and I can't see the water flow. But I figure, it really can't hurt any.

If this actually does work, there may be a market for some kind of pre-cut gasket for these things.
 
I also agree that worrying about filter bypass isn't that big a problem. Eventually the filter will process enough water to do a proper job.

Has anyone considered that filter manufacturer's design their filters to allow some bypass to help keep the filter impeller wet intentionally to provide cooling of the components?
 
I expect SOME bypass from filters as media gets clogged. But the supposed Fluval design of bypass right from the start is somewhat troubling. I found a thread that claimed that after a few weeks a partially clogged Fluval will bypass as much as 60% of its water flow. I don't know of any way to verify these claims. But if this little hack will minimize some bypass, then I figure, why not try it.
 
You are putting needless wear and tear on the motor if you restrict the bypass more than originally designed. Reducing the clogging up by adding a simple sponge prefilter at the inlet might do the trick. If you reduce the bypass then the canister itself will clogg up even faster. You are not doing yourself a favor by doing so if the intention was to increase the time between cleanings. Waiting weeks between cleanings does not sound like the best way to go with a canister.

If you wait so long that the tank starts to look dirty - and that is your indicator to clean your canister - then it is waaay to long between cleanings.
 
I have always cleaned my Canister filters monthly. I know some people that clean their filters 4 times a year. I would think you clean them when you see a decrease in the water output. If a filter has significant bypass, then you're never going to see a decrease in the flow.

I'm not trying to reduce the clogging. I am trying to ensure that as much water as possible passes through the media baskets. The sponge isn't there as additional filtration, but as an attempt or prevent water from flowing straight to the outflow without going through the media.
 
I can only go by the canisters I own, but there's no way for water flow to bypass the media on my canister filters. The only way would be if you left open gaps in the media on each tray.

I've got a cheap SunSun 302 and a Marineland C360. The suction is plumbed to the bottom of the canister and forced to go through all the media trays before it works it way up to the top and is pumped back to the tank.

HOBs on the other hand have to easily bypass in the event of plugged media, or they would overflow onto your floor until they ran out of suction.
 
Finally got around to cleaning the canister out and trying the bypass hack. it's been running for about 7 hours now. Some observations:

  1. Whenever I turn the Fluval back on, a certain amount of detritus gets kicked out of the filter, from gunk in the tubes. This detritus takes a few hours to filter out completely. With the magic eraser in place, it was gone in about 30-40 minutes.
  2. It's now 8:16 PM at night and the water flow is about half of what it was when I first turned it on around 12:45 PM.
  3. Had to seriously burp the filter to get all the air out of it.
  4. The filter seems quieter since I did the hack.

Since the water flow is cut in half now, I'm going to clean the filter again and see how clogged the pads look.
 
Check not only the pads, but also the magic eraser, to see if that one is plucked up as well.
 
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