Why a moving bed filter is not for you - Fluidized Bed Filters SUCK!

There's been a number of smaller moving bed filters on the market over the last few years and sump sized fluid bed filters are popular with monster fish keepers, but I'm here to tell you why they might not be for you, because they suck!
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[@dusk1947]

Having kept a sump on planted tanks, this method always looked like more of a hassle than it was worth. I first saw one on an Arowana tank which blew my mind. And I know they work, but there are so many easier ways to control nitrogen in a tank. While this method has numerous drawbacks which you did a great job of showcasing. Years later, I did install a moving bed reactor on a marine tank however. And it's for one very specific reason: Coral food… For context: Once you get away from K1 media, you can also find pellets made from biodegradable compounds, usually called "biopellets". These are usually polysaccharides or a polyester, with a long-chain polymer being the best option. This provides an abundant carbon source for the bacteria on its surface to grow in excess, effectively carbon dosing without dosing liquids. But they function the same as K1. Generally tumbled in a fluidized bed reactor, with a return pump instead of air slowly churning them (less noise), providing a crazy high amount of nitrification. And as the media are colonized by bacteria, and the pellets hit each other while tumbling, the excess bacteria is knocked off into the water column. This is also one of the flaws of a K1 system, you really need mechanical filtration in conjunction to capture that excess biofouling, in most cases. It’s not just that a fluidized bed doesn’t capture particulates, but it actively creates additional particulates entering the water in the form of excess free-floating biofilms. In a marine system, you can use a protein skimmer to strip that bacteria out of the water effectively do to the different chemical properties of high saline water. It’s just easier to create a foam head through fractionation in sea water over fresh water. But, that allows a marine system to rapidly export the excess bacteria, which consumed a large amount of nutrients like nitrates and phosphates in the water. And you can actually over-filter the water down to 0 ppm N or P if you’re not careful. (this is best avoided for both aquatic plants and corals, that need some level of N and P to thrive) The niche application for it is this (and why I love using a fluidized bed reactor): As filter feeders, small-polyp stony corals (SPS) regularly feed on bacteria as a major part of their diet. And many studies have shown Scleractinia’s can’t effectively utilize dissolved phosphate. Instead, they rely on bio-available phosphate from captured prey, like bacteria or zooplanktons. So, by running a small amount of biopellets, you generate bacterial food for corals which provide their ideal phosphate source for growth. And the excess is simply stripped out by the skimmer, adding another tool to the suite of filtration methods in a typical marine sump. Which is a key difference, I don’t just run one filtration method, my reef has 5 filtration tools (filter socks, a skimmer, a fluidized bed reactor, macro algae refugium, & carbon reactor). In a 300 gallon system, I only run 4 ounces of biopellets. I say all this to really show: I personally think fluidized beds are a pain in the butt and not worth the effort if you just want to control Nitrogen. But they do this one very niche application extremely well.

[@gregjonesonline]

fluidized beds are by far the best bio filter to invest in for large aquarium systems, self cleaning, lasts forever, all you gotta do is add air.

[@user-op8fg3ny3j]

Some mechanical filtration helps too

[@jcinadr]

I think it is more accurate to say they are for specific applications than they suck. First off, they are a bio filter - so the real question is do you need a high capacity bio filter. I noticed you have planted tanks - planted tanks have a lot of surface area (the plants), they already have a lot of area for bacteria to colonize, they already need decent water flow (or you get algae problems). What we deal with is often more particulate than chemical issues. So for my current tanks, I have to agree - they simply would not do much for me, and there are other filters that would work better. That said, I do believe that you could economically make one that would work very well for a high bio load aquarium, and by using wave makers rather than air pumps you could probably keep the noise down. In the end, they can be very space efficient bio filters - because ultimately that is what they were designed for (water treatment and aquaculture).

[@igorverdes]

What do you think about the oase hel-x 1 on the bottom of the canister filter. The turbulence moves it and doesn’t get clogged like other micro porous media.

[@nunoprazeres1173]

Great points for discussion. I agree and disagree... Instead of just saying that those filters suck, it should be said they are very context dependent. I can risk saying that there are much better solutions for the vast majority of the fish keepers but for more intensive aquarium addicts (like me - and probably you) 😄they are a very valid option -if not even the best one. Some of the tanks in my small fish room have individual DIY moving K1 filters and they keep water quality like no other. They are visible, of course but I am talking bare-bottom tanks anyway. I run them using a simple USB air pump which costs $5 or less and less than 2 watts to operate. I am currently building a piping system to circulate a lot of tanks through a single sump inside which there will be mechanical, chemical and biological filtration and the later will be mostly moving media (K1 and K2). Since there will be a few mechanical filtering stages before the moving media (filter sock and Poret foam matts with increasing density), I expect the water to be incredibly polished. Adding carbon and Purigen in the last chambers is also an option if I am not 100% satisfied. Keep on the great work!!!

[@brianholdridge1860]

I have two and they hang in the closet. I totally agree with these cons. Good luck with the 'doesnt suck" installment. 😀

[@tamerkesenkas1645]

I was waiting for this one

[@Peregrine1989]

I feel like the cons for the Sump version can be addressed EXCEPT for the price. Firstly while you traditionally run them via airstones, they can also be run by Wave makers, which reduces the noise significantly. Secondly why yes they do no mechanical filtration by themselves, you cam combine them with another form of filtration to fix that. Most obvious of these is an UGF, a filter sock OR in Sumps with s bend designs (rather then drilled holes) the sponge required to stop the K1 escaping the fluidized chamber Really though you are correct...like ANY sump they are only for large tanks with either monster fish OR overstocked African cichlids.

[@laurabustos6560]

I've never even heard of this type of filter! I guess I'm learning some stuff today!! ✌️

[@daviddalpe4663]

Hi Bentley, I have k1 in a 2 liter pop bottle in a 30 gallon tank. I hide it behind plants.

[@John-Ebsen]

I have one of the ziss filters in a 75, but it's a supplemental filter and glorified air stone. I've seen some very impressive and huge MBFs in giant koi greenhouses.

[@BlarglemanTheSkeptic2]

I recently designed, built and installed a fluidised filter in a 180L tank that is virtually invisible and silent. There is currently about just under a gallon of the media tumbling, with room to double up as the fish grow. The filter has place for the heater, water polishing and a large plant to suck up excess nutrients from the flow. It's only just come online, so other than the aesthetics (very quiet with limited visibility in the tank), it's too soon to comment on performance in the real world (though I do know that the media processes ammonia efficiently, having gone through a 7 day fast cycle separately).

[@Karp_Keeper]

Since I don't have a dedicated filter room, running the air stone at night solves the noise issue for me. Though, this allows waste to build up on the sump bed if there's no bottom drain.

[@JohnWood-tk1ge]

I put a Ziss in my fifty five gallon super red pleco breeding tank along with a box filter and a sponge filter ( over filtered). But it’s a colony breeding tank and it is the tank I move the sponge to new tanks and replace. I am weird because I like the look of the three filters because I can look and see them running. Plus I know what they are doing for the tank!

[@Wendy-ir6ww]

I'm kind of torn between using this as a sump in my planning for a set of large (over 2,000 gallon) fish tanks & a refugium with a sump, so I'm definitely looking forward to your next video on this. But also one note - beyond K media, many people I've seen use expanded clay pebbles as the media for them, which does help keep the costs down a little.

[@tonyadams4726]

I haven't tried them yet but it doesn't sound like something I would want to anytime soon lol

[@nicogall.8351]

Hi Friend, I greet you from Italy. There is a lot of confusion about this filter. After all, aquarium farming is like this. Everyone has their say. About this filter: It can be used as a single filter. No, it cannot be used as the only filter but must be accompanied by a traditional filter. What is the truth?

[@joehanney3495]

Makes me wonder. With all the information coming out about microplastics and its spread. We then have bits of plastic bumping together in a closed loop system, if any or how much is this polluting aquariums/ponds?

[@user-op8fg3ny3j]

In our water supply too

[@robertpurvis9659]

Everything you said is directly opposite of what all the other people say about sand filters

[@lukewang1997]

Are you going to do a bog filter?

[@BentleyPascoe]

No, hard to actually do them at any small scale

[@mikeeljahosafats3231]

I don't get it. 0 ammonia is 0 ammonia. Why does it matter if a million strong bacteria at it all or if 2 million weak bacteria at it all?

[@beerprem]

Moving bed filteation iscgreat for aquaculture or other highly intensive operations.for home fishkeepers its overkill and a waste of space, any reasonably stocked tank wont use even 1% of its capacity.