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Thread: Static vs Moving bed filter?
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27-08-2019, 12:24 PM #1
Static vs Moving bed filter?
Hi/ Hope everyone is well! What are peoples thoughts on static vs moving bed filters? Thank you!
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30-08-2019, 11:13 PM #2
In my opinion, static should only be used for mechanical filtration.
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31-08-2019, 12:27 AM #3
Thank you Mike.
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freddyboy Thanked / Liked this Post
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03-09-2019, 08:57 PM #4
Bead filters are static..... mine give me the best water I have ever had.
Just sayin
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04-09-2019, 12:10 AM #5
Thank you Andy.
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freddyboy Thanked / Liked this Post
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05-09-2019, 12:32 AM #6
Quite an interesting question, and one with many ifs, ands, (water) buts, and maybes!
I am going to take the liberty of tentatively assuming that you are not referring to the use of static beds for mechanical filtration purposes, but purely for biological purposes. If I am wrong in that assumption, then much of what I am about to say may not be relevant.
I am also going to assume (perhaps incorrectly) that you are referring to static filters that employ the same type of plastic media as moving bed filters (although Japmat is still quite popular around the world, for static bed filtration, it generally tends to be used with plenty of aeration).
I am further going to assume that you mean static as in no aeration (since, in the case of using plastic media, aeration would tend to imply a moving-bed rather than static).
I realise I'm making quite a few assumptions, above, and you may well disagree with my assumptions - that's totally fine - I'm making these assumptions partly to allow me to discuss a few aspects which might be of interest, intellectually/theoretically, even though they may not turn out to directly relate to your intended definition of 'Static Bed'.
With all of that said, I think one of the main reasons folks in the UK can be reticent about using static bed filters is that, over the longer term, waste may be more likely to accumulate than in a moving-bed filter, so there is a possibility that anaerobic bacteria might begin to proliferate, with the potential to harm fish health. This can particularly be a risk if one does not have the luxury of an RDF as their first line of defence against waste accumulation in a static bed filter.
Another aspect is that the volume of space occupied by a static bed filter may be more efficiently used by a moving bed filter, since nitrifying bacteria thrive in an oxygen-rich environment and thus may more efficiently metabolise food and fish waste than an equivalent sized static bed filter. One could counter this by arguing that a moving bed filter requires more space between the media, in order for the media to move, whereas a static bed filter can be fully packed with media, thus increasing the amount of surface area. This is a contentious aspect, then, especially since it also depends on how much oxygen is present in the water prior to entering the static bed.
Although I'm not outright-prejudiced against non-aerated static-bed biological filtration, I would, personally, choose an aerated moving-bed in a heartbeat, unless there was a very specific reason to require a static bed biological filter. There are so many positives to a moving-bed bio filter, with perhaps the only significant downside being that they tend to do very little to de-nitrify the water, and that is something that can be remedied, to a resonable degree, with a trickle tower or bakki shower, downstream of the moving bed filter.
What I do find interesting, though, is that there are a number of cultural differences in koi pond design and filtration design, between, for example, the German, the French, and the British. One of these cultural differences is that the Germans seem to be quite at ease with using non-aerated static bed filters (again, for the purposes of this discussion, I am choosing to define 'static bed' in terms of using plastic media equivalent to that used in a moving bed filter)
It is quite common to see German ponds with an RDF, followed by a moving bed filter, followed by an almost identical static filter, using more of the same media. Although there is a tiny bit of aeration in the first of these videos (marginal aeration with static media being the '3rd option', in between moving bed and zero-aeration static bed), you get the general idea, and there are many German ponds with zero-aeration static-bed chambers included):
https://youtu.be/AqLQiUMkzK0?t=12m55s
https://www.youtube.com/watch?v=aQhEI7T3fAk
https://www.youtube.com/watch?v=v5_Ia6VMqK4
The Germans also seem quite at ease with static bed filters using japmat with zero aeration (although they may have an identical japmat chamber earlier in the filtration chain that does have aeration).
https://youtu.be/2fAm1n7W9Dg?t=193
Non-aerated japmat chambers seem to have gone out of fashion in the UK, what with multibay filters declining in popularity, in recent years, and I feel there is some legitimacy to being wary of non-aerated static beds, regardless of whether they are filled with japmat or hard plastic media, but this risk could, arguably, be largely mitigated by the use of a decent RDF and regular flushing of the media, to remove any build-up and stir-up any anaerobic zones. It can be very helpful to build a 'dump-to-waste' valve at the bottom of a static-bed chamber, to make for easy removal of trapped solids. Then the issue becomes one of simply 'do the benefits of a well-managed static bed filter outweight any potential risks?', and that really comes down to the opinion of the individual pond owner, and how much manual labour they are willing to do, to keep everything well-maintained, hygiene-wise.
If someone is considering using a static-bed filter purely because they wish to perhaps gain a bit more de-nitrification ability in their overal filtration chain, then it might be safer to simply build a trickle tower with deliberately restricted ventilation (since at least the passage of water through the media should prevent any risky sludge harbouring pathogenic anaerobic bacteria), or simply build a normal trickle tower with some decent ceramic media in it. I think I recall MankySanke discussing restricted-ventilation trickle towers, somewhere, but I just had a quick look on his website and can't find it.
If, however, the desire for static filtration is partly for mechanical filtration and partly for simultaneous nitrification activity, then, broadly-speaking, I don't see any significant risks with it, provided the static media is regularly flushed, just as it is in commercial implementations such as the Nexus or Spierings filters.
https://www.youtube.com/watch?v=V-zW0asvkgI
https://www.youtube.com/watch?v=auG-FtLSwrc
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P.S. One of the most extreme examples I've ever seen of using non-aerated hard plastic for the purposes of biological filtration is someone who was promoting the use of large-bore (approx. 10") pipework, with corrugated plastic tubing (just like a vacuum cleaner hose) packed inside the 10" pipe along its entire length, so that as the water circulates throughout the pond system, it gets nitrified and somewhat denitrified along the way. With no disrespect intended to the progenitor of the idea, although it may seem like a clever idea, I personally feel it was/is a step too far, with the risks of unseen sludge accumulating anywhere (or entirely throughout!) the system are, surely, exceptionally high. Therefore, it could, in the longer term, end up being a pathogenic biological disaster for the pond system.
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P.P.S. although this japmat chamber is aerated, the principle of a bottom-mounted 'dump-to-waste' valve can be seen here:
https://www.youtube.com/watch?v=KxKb...youtu.be&t=688Last edited by MustBeSomethingInTheWater; 07-09-2019 at 12:49 PM.
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05-09-2019, 04:40 AM #7
Hi/ Thankyou for very detailed reply. I've been looking at all the filter options on the market, and keep going backwards and forwards with the choices! And I've read a lot of them suffering with water tracking issues. Is there any issues with tracking in the moving bed filter set up? My feeling and guess would have to be if it did exist,it would be greatly reduced by the strong movement from the aeration? Thankyou again
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freddyboy Thanked / Liked this Post
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05-09-2019, 10:53 AM #8
Tracking can occur in moving-bed filters, but there are things you can do to reduce this tendency.
* Diffuse the incoming and outgoing water, so that the water is not travelling from a single specific point to another single specific point. This means building a very simple multi-hole manifold at the inlet and at the outlet, so that the water is forced to pass through a number of different holes instead of just one big one. Diffusing the water also has an additional benefit - it reduces the likelihood of the bio media congregating around the outflow (which can be a particular nuisance with higher pond turnover/flow rates, and especially if some of the bio media is of the very lightweight, non-hollow, 'flake' type, such as Mutag Biochip or Eco Pond Chip, etc.)
* Build the filter so that it has a considerably larger volume than what is actually required for the floating media itself. This is so that more mixing has a chance to occur before the incoming water exits the filter. This aspect can be quite commonly overlooked by people who have perhaps been tempted to simply calculate how many fish they wish to own (and their probable future size/mass), how much food they are likely to need to feed that many fish, and how much moving bed plastic media the manufacturer claims to be necessary in order to handle their calculated food loading. If I calculate, (and this is only a flippant example, for illustrative purposes, so don't take the ratios too literally), that I need to buy 50L of a certain brand of bio media (K1, Hel-X 13, or whatever), then the moving-bed chamber might need to be that size plus another, say, 50-100L for water, to ensure good fluid movement of the media. However, that doesn't take into account the possible benefit of oversizing the fluid chamber to improve mixing and reduce tracking. So give this some consideration. If you only have limited space for the filter, then so be it, but if you are able to, it can definitely be worthwhile to oversize the chamber, for the reasons I've described, even though you don't need to oversize the quantity of bio media within it. As a convenient bonus, it also gives you more freedom to add more bio media, in future, if you find your pond biomass increasing above your original estimates. Also remember that you don't necessarily need to buy a fancy moving-bed filter chamber from a koi dealer - there are many generic large containers, of various sizes, available, off-the-shelf, from agricultural equipment suppliers, as well as garden centres (water butts, etc.), and IBC suppliers.
* Although not essential, you can have the water enter at the top-left of the filter, and exit from the bottom-right of the filter, so-to-speak. It's tempting to presume that by doing this, the incoming water has to 'struggle' against the upflow of the aeration, in order to make its way downwards to the exit, but that would be an over-simplification, since the water is circulating anyway (as one region of water is moving upwards, another region of water must be sinking). Nonetheless, by having the inlet and outlet as diagonally far away from each other as possible, you are maximising the distance the water has to travel through the filter, and thus you are maximising the opportunity for water-mixing to occur. You don't need to cut a hole in the bottom exit of the filter chamber - you would only need to have the diffusor holes located there, so the diffusor manifold could be permanently 'dunked' or submerged in the filter chamber, but with it's physical pipework actually leaving the chamber at the top (am I making sense to you?)
You're never going to achieve perfection in trying to avoid tracking, but employing one or more of the above can be helpful. As you've already gathered, the aeration helps mix the water, but it can still be worthwhile including simple design features to improve the efficiency of mixing / minimise the possibility of tracking.
Another feature you can include on a moving bed filter, is a valve installed at the bottom of the chamber (and in this instance you really would tend to cut a physical hole in the bottom of the chamber). This hole would have stainless steel (or hard plastic) mesh over it, to prevent plastic bio media passing through. The idea is that, every week or so, you can open the valve and dump a moderate quantity of water to the sewer, with the aim being that as it leaves the chamber, it will flush away any accumulated waste matter, just as you can see in the video I linked at the end of my earlier reply (note the transparent pipework is helpful to see when the waste has been cleared). Few people in the UK have enough space for an IBC chamber (1 cubic metre / 1000L), but IBCs are popular in Germany and also happen to have a valve installed at the bottom, as a standard manufactured feature.
I wouldn't get too hung-up on including a dump valve on a moving bed filter, since they tend to keep themselves fairly clean, if you have decent mechanical removal of waste before the water enters the filter, but if you know you may have poor mechanical removal of waste, then a waste-dump valve could turn out to be well worth the effort, over the longrun. You'll have to consider the pros and cons and draw your own conclusions - I'm only mentioning it as an option for you to consider.
As a side-thought, if you go ahead with installing a dump-valve, and if you're still keen on a static-bed bio-filter, then you could even consider installing aeration (just as you would with a moving bed filter), but with the idea being that you switch on the aeration only when you want to agitate the media for cleaning purposes, then dump the sloughed-off waste through the bottom dump-valve, and switch the aeration back off.
There is a wealth of experience (and differing opinions) on the forum, so I'm sure you'll find enough information for some ideas to begin to crystallize in your own mind. Everyone has a different spin on how to go about designing filters, so, provided you have made yourself aware of some of the issues, and some of the known workarounds, you should be successful.
To be quite frank with you, the biggest filtration issue is efficient mechanical removal of waste. Since RDFs (Drum filters) are still not exactly cheap, it can be a challenge to filter waste in a way that is efficient and effective, yet doesn't turn the pond-owner into an unwilling slave, in terms of frequent maintenance. IMO, bio-filters are secondary in importance to primary mechanical filtration of waste - have you decided on how you intend to filter the pond waste/solids?
P.S. I noticed milaz posted some info on filter sizing 18 months ago:
https://www.koiforum.uk/water-treatm...tml#post260494
(Oversizing a filter, in order to improve mixing, is a seperate consideration, so would need to be considered after any such calculations).Last edited by MustBeSomethingInTheWater; 03-10-2019 at 01:35 AM.
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05-09-2019, 02:57 PM #9
Hi/ Thankyou again for your very interesting response, I find filtration much more interesting them talking about the fish themselves! I'm new to RDF filtration, but what i have read and understand they can't be beaten. But to be honest I must admit I'm a bit worried and concerned about any reliability issues. I also like the idea of using a ibc tank, but can't find much details or videos on how best to make them or the best set up regarding the internal manifolds and pipework. What you have also said about water entering the top left and existing the bottom right makes great sense to me. I've seen a ready made moving bed filter with what setup you spoke about with the inlet and outlet made up with a Diffusor holes, which looks very good and would stop any media escaping during any flushing. But the inlets and outlets both face one another sited at the bottom of the filter and I just wondered if that were the best locations for mixing! Thankyou Again!
Last edited by Maddog1; 05-09-2019 at 03:58 PM.
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freddyboy Thanked / Liked this Post
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05-09-2019, 05:44 PM #10
haha - I laughed at your remark that you find filtration more interesting than the fish - in some respects, I know what you mean - they are intriguing to a practically-inclined sort of mind.
Here's a couple of informative web resources you might enjoy:
Index of /~rstrange/wfs556/html-content
L.S. Enterprises
There's no need to get too bogged-down in the smaller details of design, provided you've got a reasonable grasp of the overall principles and the potential pitfalls, which it sounds like you are rapidly getting up-to-speed with.
Is it reasonable to have the inlet and outlet both situated at the bottom of the filter, on opposite sides? Well, yes, that's certainly acceptable, but I think you can understand why it might be even better to enter at the top and exit at the bottom, with them also being diagonally as far apart as possible, given that, notwithstanding the mixing action of the aeration, water will nonetheless attempt to travel the shortest path from inlet to outlet. Either approach will still function acceptably, though. For moving bed filters (MBBRs - Moving Bed BioReactors), I would encourage you to DIY your own, if you have reasonable DIY skills, since MBBRs are fundamentally very simple filters and commercial offerings tend to be shamefully overpriced in the Koi hobby - Oase being one, but by no means the only, example of this overcharging:
https://www.youtube.com/watch?v=uoFG0e4oGIM
https://www.youtube.com/watch?v=D-j-9DW3u4I
https://www.youtube.com/watch?v=VVJw93w-p7c
It's an absolute flippin' disgrace how much some vendors charge for a plastic tub with an air diffuser in it, and the same goes for so-called 'combi' RDF units, where the RDF has an adjacent MBBR chamber to form a combined single unit).
If you can afford to invest in a standalone (non-combi) RDF, then that's great, and they really are the best option for mechanical filtration of solids waste. ...but for the biological aspect of filtration, you could save a packet by building your own MBBR, and there's an above average chance it'll be better than any of the commercial offerings, if you use your common sense in designing it.
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If you have the patience to trawl through the many videos on the channel, you'll find quite a number of Modern Koi Blog episodes showing IBC-type MBBR filters, to inspire you:
https://www.youtube.com/user/KonishiKoiFarm/videos
For example, I posted one earlier, and here's a few more from that channel:
https://www.youtube.com/watch?v=iUqlOGlVMlM
https://www.youtube.com/watch?v=sOWUChX3nlM
https://www.youtube.com/watch?v=-nxSeVDKm9U
https://www.youtube.com/watch?v=BCXxT85Lpho
https://www.youtube.com/watch?v=aoawct1zX4Y
https://www.youtube.com/watch?v=osoI6Sr3-0c
https://www.youtube.com/watch?v=WCL9Ikw3lGM
These are only marginally relevant, but may be of passing interest:
https://www.youtube.com/watch?v=-JJQFEk-jWA
https://www.youtube.com/watch?v=c3ymEy51NEM
https://www.youtube.com/watch?v=xoAiTiPSD7U
and you may get some insight from this video:
https://youtu.be/8TmT2Qc8a-g?t=134
I would counsel you to steer clear of using submerged brushes (called 'burstenfilter', in Germany) for trapping solids, as they turn the owner into a slave, for daily messy cleaning, without which, one may experience endless fish health issues due to decaying waste. I'm linking the above video more to help you see the way the pipework is attached to the IBCs (or similar smaller generic plastic containers), using large flanges (also see www.mega-koi.de/produkte/pe-zubeh%C3%B6r/pe-hd-flansche/)
Water tanks:
https://www.tanks-direct.co.uk/water-tanks.html
https://www.koiphen.com/forums/showt...ond-Filtration
Interesting tangential information, regarding biofilms in filter systems (German Blog, translated):
https://translate.google.co.uk/trans...-text=&act=urlLast edited by MustBeSomethingInTheWater; 05-09-2019 at 08:18 PM.
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05-09-2019, 07:18 PM #11
Hi/ Thankyou for your response, loving the German channels, love both the ponds and fitter systems. Just wished we had content like this in the uk. Loving the ibc filtration systems some great ideas, the last one with the 4000 litre ibc looks so simple to built and the water looks so clear. Shame about the pitfalls with regarding high maintenance with cleaning the brushes and decaying waste causing health issues. Thankyou
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05-09-2019, 08:52 PM #12
Just for side-interest, with regard to the 'static yet mildly-aerated' option, here's ceramic being used in that manner. I'm not convinced that this is the best way (longterm) to use ceramic, since it may be more liable to clog with mulm, biofilm, and algae, than if it was in a shower configuration, but it'll probably give at least 18 months of fantastic nitrification and denitrification performance:
https://www.youtube.com/watch?v=g2-RIrVa7mw
Note that this ceramic is the silicon-carbide type that is more like a foamed lattice (very open pore structure) kind of ceramic than the likes of BHM and other ceramic logs.
(In case you're wondering how on earth the guy can afford so much ceramic, my guess is he's probably importing the stuff directly from China, by the shipping-container load, given that he retails the media to hobbyists).Last edited by MustBeSomethingInTheWater; 14-04-2020 at 09:42 PM.
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05-09-2019, 09:11 PM #13
Wow! That water in the filter looks Lovely! These Ponds and filters just blow my mind! Thanks for sharing.
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freddyboy Thanked / Liked this Post
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06-09-2019, 07:00 PM #14
Thanks for the very interesting posts MBSITW...best posts on here for a while. Some good points made.
That last filter...lol.
Most ponds are smaller than that.
What’s the powder he’s putting in at the end, do you know?
Sent from my iPhone using Tapatalk
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07-09-2019, 12:22 PM #15
Cheers mate.
The powder you asked about is just filter bacteria, to seed all that ceramic a bit faster:
http://kois-fuer-kenner-shop.de/epag...e/Categories/4
It's virtually identical to AquaBio5 (might even be rebadged, but I don't know)
http://happykoi.eu/Aqua-Bio-5-neu
Nice little pond in their promo:
https://www.youtube.com/watch?v=7F3IyEToHfU
...and yes, that last filter is a bit crazy, but if you can find any koi enthusiast who isn't at least a little bit crazy, in one way or another, be sure to let me know!
I admit I had to laugh when I first saw that vast quantity of ceramic being used - I thought to myself "at that rate why didn't he just seal up his shipping container full of ceramic, from China, and hire a plasma cutter and mig-welder, to simply install an inlet at one end and an outlet at the other - No hole in the ground necessary!"Last edited by MustBeSomethingInTheWater; 07-09-2019 at 12:44 PM.
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08-09-2019, 06:19 PM #16
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freddyboy Thanked / Liked this Post
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13-04-2020, 07:16 AM #17
A sorry for thread resurrection 😋
One point to look at the problem it attempting to solve, nitrification using bacteria.
https://en.wikipedia.org/wiki/Nitrifying_bacteria
Ammonia nitrification to nitrite requires oxygen. The process is an oxidisation. Hence aerobic bacteria with an oxygen feed such as an airated moving bed filter.
Nitrite to Nitrate is also an oxidisation so requires oxygen from somewhere. Again aerobic nitrifying bacteria perform this.
Denitrifting bacteria convert Nitrate to N2 or N2O. Again most are aerobic bacteria.
https://en.m.wikipedia.org/wiki/Denitrifying_bacteria
However not all bacteria perform these steps are aerobic themselves - they can be anaerobic, it depends on the bacteria species you have.
An interesting (but heavy) study here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438332/
Best plants to remove Nitrate
pug has a very impressive veg filter on his pond, have a look at some of his his youtube videos....