# Moving bed filter, Kaldnes K3 Filter Media question?



## peter hardman (Apr 23, 2010)

Hi everyone :thumb: .
I was wondering if anyone can give me their opinion about, or there experiences with, the Kaldnes K1 or K3 moving bed filter media.
I was looking at adding it to my already set up F/W sump, I am also setting up a new 6ft tank for Tangs with the idea of using it in the new sump too.

Any suggestions, opinions, thaughts on using it would be greatly appriciated.

Thanks. Pete.


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## fmueller (Jan 11, 2004)

I can't say that I've ever hard of Kaldnes, nor am I familiar with the concept of 'moving bed filter media'. If you have seen it online, maybe post a link and I can check it out. Might be some fancy stuff only you folks down under can get :wink:


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## peter hardman (Apr 23, 2010)

Hi, thanks for your interest, here is two youtube videos for you to look at. Let me know what you think.









I have done a few DIY projects with good success using cut drinking straws or bottle tops with holes drilled in etc. They do take some time to mature but when they do they work very well. I'm not a fan of placing anything into the tank if not nessasary so mine were either built into the the sump or sat beside the tank in containers.

I have ordered 14 litres of the stuff and have a tank and filter ready set up (6ft) for their arival, when I get it all up and running I will post a vid on here.

Cheers. Pete


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## fmueller (Jan 11, 2004)

Interesting. Thanks for sharing this. I've built a Fluidized Bed Filter (FBF) for my 240G when I first set it up, but am no longer using it. From what I see, a 'moving bed filter' is the poor man's FBF. The smaller the particles, the larger the total surface area is going to be. Sand is hard to beat in this regard, and the moving bed filter has much larger particles.

By moving the particles around you optimize the percentage of the surface that can actually be used effectively, because no part will be permanently covered by something else. That would usually be a huge problem with sand, but is no great problem with media that are less densely packed, such as bio balls or the things in this moving bed filter. That's why moving them around will have a much smaller effect than for example with sand.

The reason I am personally no longer using FBFs - or any specialized bio filter media - is that I don't believe available surface area is usually the limiting factor for bio filtration. Especially when things go wrong, oxygen content in the water can become a limiting factor. That's why I try to keep oxygen at saturation levels. If that's the case, nitrifying bacteria will always find surface area to colonize - be it in the tank or in the filtration system.

In short, I think a moving bed filter will be overkill for bio filtration, because the media will provide more than enough surface area even in the non-moving state. But to each his own. Having your bio filtration media move around certainly can't do any harm :thumb:


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## peter hardman (Apr 23, 2010)

Thanks fmueller for your input an info :thumb:.
I enjoyed the read on the FBF, hmmm interesting. 
You have made me do a re-think on my plans which is good.
What you said all sounds good, well put.

Cheers.
Pete


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