Hvordan og hvorfor virker Zeolitfiltrering..Lang post!

[leifkrarup]

For de interesserede!
Der mangler et par diagrammer som ikke kunne gengives her...men de er ikke så vigtige og artiklen kan sagtens læses uden.

By Jens Kallmeyer

[Editorial note: The author wished to state that he does not advocate the use of any specific brand of Zeolites and/or additives. He is not connected with any company selling these products. Jens can be reached at kallm@gmx.de]

Zeolite Filtration for marine aquaria became popular a few years ago. Since then, it has caused a lot of discussion among hobbyists. While some hobbyists consider it the "Holy Grail" of coral keeping and enthusiastically promote this technique, others condemn it with as much enthusiasm.
What is lacking in most of the Pro/Con discussion is an actual explanation of the principles that lie behind this technique. Unfortunately, little information that goes beyond, “Use as stated in instruction manual” is provided by the suppliers of Zeolite Filters! In the earlier days, when this technique was still brand-new, more than just a few aquaria suffered from severe coral die-off after switching to this technique. These unlucky events were not restricted exclusively to inexperienced beginners, but rather to those that have kept a marine aquariums for many years. There are many beautiful tanks with Zeolite filtration. There is ample proof that the method does work very well, with massive improvements in keeping extremely colorful SPS corals. Why does it work in some tanks and not in others?
Zeolites have been well known in freshwater aquaria for a long time. Their ability to reduce nutrient concentrations quite rapidly tempted marine aquarists to try freshwater Zeolites in seawater tanks. In almost all cases these tests ended in a major catastrophe. So what is the difference between those "tank-killers" of the past and the new Zeolite filters? It is definitely not the design of the filter itself, which is basically a large canister-filter with a high flow rate.
First, it is the kind of Zeolite used. Second, it's the way of using the Zeolite as part of a whole concept. Apparently, there are more things to consider than just buying a pack of Zeolite and tossing it into a canister-filter. Before going into the details, it is important to understand the basic principles behind this filter system.
Let’s start with the basics and ask the question, "What actually is a Zeolite?" Zeolites are minerals, and consist mostly of silica and aluminium, plus other elements like Sodium, Potassium, Iron, and Manganese. The most interesting feature of Zeolites is their crystal structure. You can think of Zeolites as a sponge with holes of different sizes. The small holes are the size of single molecules, about one billionth of a meter. The size of these holes depends on the chemical composition of the mineral. There are hundreds of different Zeolites known in nature, and also many different synthetic Zeolites.
What makes these minerals so special is their ability to absorb specific compounds. Depending on their composition, they preferentially absorb different compounds. This means that they are more likely to absorb one compound more than the other if both are available. For many industrially-used Zeolites, their absorption preferences have been determined. However, thinking of Zeolites just as "absorbers" is a bit oversimplified. They are actually ion-exchangers. The holes to which a compound binds are not empty, but rather filled with sodium or potassium. As soon as a preferred compound is available, another compound, usually--sodium or potassium, is given off, and the compound will be absorbed. This reaction, the replacement of one ion for another ion, is called ion-exchange.



The diagram on the left represents fresh Zeolite. Sodium (Na) and Potassium (K) ions are ready to be exchanged with other positively charged ions. The diagram on the right represents the release of Sodium and Potassium in exchange for Ammonium ions.
This "ion-exchanger effect" itself is of limited importance for the use of Zeolites in filtration of marine aquaria (there are some other tricks that will be explained later). However, it is of great importance in industrial applications. It is possible to produce synthetic Zeolites with very specific ion-exchange capabilities that can be "pre-loaded" with specific ions which will then be exchanged against other ions. In marine aquaria, the liberation of sodium or potassium is most probably negligible, as they are major constituents of seawater anyways.
Why did so many earlier trials with Zeolites in seawater end unsuccessfully, even though they worked perfectly in freshwater? The answer is easy: The Zeolites commonly used in freshwater adsorb ammonium, which is a desirable function in fresh, AND seawater. However, Zeolites do prefer calcium. Now, you can imagine what happens in seawater! There is usually little to no calcium in normal freshwater, so the Zeolites absorb ammonium. Because there is a lot of calcium in seawater and because these specific Zeolites prefer calcium, the calcium values drop instantly, with sometimes catastrophic results. In the earlier days, when marine aquarists experimented with freshwater Zeolites, they ended up with very low calcium concentrations of less than 200 mg/l.
The Zeolites now used for seawater preferentially absorb ammonium, but this is just one half of the story. The other half is where the biology comes in. As already mentioned, Zeolites have a very porous structure. Under the microscope, they look almost like a sponge. The larger holes are MUCH bigger than the smaller ones, about a thousand times bigger. This porous structure creates a large surface area for bacteria to settle. As the ammonium is adsorbed by the crystal structure, the bacteria living on the Zeolite get their food delivered to their doorstep. To enhance the filtration capacity, a carbon source is added, in most cases not directly into the filter, but into the aquarium. In most cases, aquaria are carbon limited.
Therefore, by adding a carbon source, all bacteria in the tank receive some additional food. But as those bacteria that sit on the Zeolite get the ammonia much easier and in much greater quantity than others in the tank, they can make much better "profit" from the carbon addition. To speed up the starting of these filters, some companies offer bacterial starter cultures, although their usefulness is debatable.
Now that we have discussed the basic principles of what happens on the Zeolite, we should take a look inside each grain. Due to the porous structure of the material and the bacterial films coating the surface of each grain, oxygen will rapidly be depleted inside the Zeolite. At the very surface, where oxygen is still available, the ammonium is either oxidized by autotrophic bacteria to nitrate, and then immediately reduced to nitrogen gas by heterotrophic bacteria, or the ammonium may be reduced to nitrogen directly.
The latter process (anaerobic ammonium oxidation, anamox) is known to occur in sewage treatment plants, and has only recently been identified in nature for the first time. Proof of whether or not this process is occurring in a Zeolite filter would be highly difficult, if not impossible. This shouldn't bother the users of these filters; the net reaction is the same: ammonium is removed from the water and transferred to nitrogen gas, which goes off into the atmosphere. All these reactions can only take place when a carbon source is added. Without a carbon source, the filter would first only absorb ammonium and nothing else. It would be a simple ion-exchanger. After a few days to weeks, chemoautotrophic bacteria would settle on the ammonium-loaded Zeolite and oxidize it to nitrate, as indicated in the following reaction:
NH4+ + O2 + 3OH-= NO32- + 2 H2O
Therefore, such a filter would actually produce nitrate, and its use for aquaria would be rather limited! When I said previously that the ion-exchange process itself is not of much importance in the marine aquarium I may have been a bit too simplistic. Over the last year or so, many people actually have used this effect in a very elegant way. In new tanks, a little powerhead with a cartridge full of Zeolite can have a very positive effect on the stability of the tank. As ammonium is oxidized to nitrite, a reduction of ammonium levels reduces the nitrite peak in the start-up phase considerably. As the excess ammonium is taken out of the system before it is oxidized and starts causing problems, the Zeolite filter acts as a buffer which stabilizes the nitrogen cycle in the tank. In such a case, the Zeolites have to be changed every few days and no carbon source is added.
In the “normal” Zeolite filters with the addition of a carbon source, these filters can run for extended periods of time because ammonium is constantly removed from the minerals by the combined efforts of autotrophic and heterotrophic bacteria. After a while, the Zeolite is exhausted and needs to be replaced. If the bacteria remove the ammonium from the minerals why doesn't the filter run forever? First of all, the bacterial films will slowly clog up the pores, thereby reducing the adsorbing capacity, secondly other ions will also be adsorbed onto the Zeolite. As the bacteria do not remove these ions (at least not preferentially), they will slowly become enriched and therefore reduce the number of places available for adsorbing ammonium. In industrial applications Zeolites are often recycled. This is definitely not an option for the home aquarist, as it involves the use of highly aggressive liquids. If you try to do this in your kitchen you endanger your family's health and that of other people! Saving money this way is just downright foolish. If you decide to set up a marine tank, make sure you can afford to maintain in properly.
There is also another method of nutrient removal working in Zeolite filters. As the bacterial biofilms build up, a lot of nitrogen compounds are actually fixed in the biomass and thereby removed from the water. When the biofilms become too thick and rip off, the skimmer may catch them and thereby remove these biologically fixed nutrients from the water.

The diagram on the top represents bacteria taking advantage of the locally high concentration of Ammonium trapped in the Zeolite and breaking it down to Nitrogen gas. The diagram on the bottom represents well fed, nutrient rich bacteria that have reached the end of their lives drifting from the Zeolites, destined to be skimmed out of the tank.


Since these filters entered the market, they have been proven to keep nutrient concentrations at levels usually found in the central Pacific, one of the most nutrient depleted waters on Earth. Extremely colourful SPS imports from Fiji, Tonga, etc., that often went brown rather soon, now keep their amazing colours. For many users, this system provided a breakthrough in SPS-keeping. Even some long-time SPS enthusiasts with amazingly beautiful tanks running on different filtration systems seem to get more colourful corals after changing to Zeolite filtration.
The major advantage of these filters is also their major danger: They remove ammonium very rapidly and extremely efficiently. Although ammonium concentrations are never high (at least they should not be), it is a very important component in the nitrogen cycle. By removing it almost completely, all other processes will be influenced as well. When these filters entered the market, some people underestimated their effects on the overall chemistry of the tank. In rather old tanks with higher nutrient concentrations, the corals were well adapted to these conditions and the sudden drop caused massive die-off of colonies that had been growing well over decades. The corals starved and became susceptible to parasites and diseases. If the corals did not starve to death, the parasites killed them. It seems that tanks that have started with Zeolite filtration run very well and without major problems, while old established tanks are much more sensitive to it.
When switching from a different system to Zeolite filtration, some reports mention times of up to one year before the effects of the new system came fully apparent. Don’t forget that Zeolites are the most effective ammonium absorbers available. Keep a close watch on your corals, and measure the nutrient levels at least once a day over the first week. If the corals react too drastically to the changes in water quality the amount of Zeolite needs to be reduced.
If you are tempted to try your luck with such a system, go ahead. It is a good way to an amazing aquarium. It is not much easier, cheaper, or better than several other methods that are available on the market--it is just different. It will not liberate you from proper and regular maintenance of your tank, and there is no guarantee that your tank will look like the one that made you consider trying this method! Whatever you do, be conscientious and patient. No system can cope with the lack of knowledge, laziness, and impatience of the owner. Happy Reefkeeping!

[Hvidtfeldt]

Vil da lige læse den igennem lidt senere hvis du kan anbefale og læse den?

[Musiker]

Jeg syntes den er god, et link til orginalen ville være rart
Han er geolog og her er hans akvarie bygge tråd:
http://reefcentral.com/forums/showthrea ... genumber=1

[leifkrarup]

Jeg syntes den er god, et link til orginalen ville være rart
Han er geolog og her er hans akvarie bygge tråd:
http://reefcentral.com/forums/showthrea ... genumber=1

Jeg troede du havde set den på Zeoforum!:-) Men her er den i hvertfald.
http://www.wetwebmedia.com/ca/volume_1/ ... ilters.htm

[leifkrarup]

Vil da lige læse den igennem lidt senere hvis du kan anbefale og læse den?

Den har ihvertfald givet mig svar på noget jeg ikke vidste omkring virkemåden.

[StarF]

spænderne læsning.. syntes dog stadig bare zeovit er for dyrt på store akvarier.. ellers var jeg da klart gået over på det.

[leifkrarup]

spænderne læsning.. syntes dog stadig bare zeovit er for dyrt på store akvarier.. ellers var jeg da klart gået over på det.

Har du prøvet at regne på det...jeg synes altså ikke det er så dyrt når man først har fået startet op....men alting er jo dyrere til et stort akvarie, ingen tvivl om det...zeolitsten og aktivt kul skal jo skiftes hver 8. uge.

[StarF]

sidst jeg regnede på det, mener jeg at jeg kom frem til ca 1000kr om måneden... kan self ha fucket udregningen op

[leifkrarup]

sidst jeg regnede på det, mener jeg at jeg kom frem til ca 1000kr om måneden... kan self ha fucket udregningen op

Med al ære og respekt...det lyder helt hen i skoven du har 4x så meget vand som mig og jeg tror jeg bruger 60-80 kr pr måned. Så kan du jo selv gange op. Vædskerne regner jeg ikke for noget for de rækker meget længe....men som sagt skift af kul og zeolitsten hver 8. uge er nok den største udgift.
Man sparer jo så drift af ozon, uv samt fosfat og nitratfilter da disse skal kobles fra. Men hvis jeg var dig ville jeg nok også vente til vi andre har nogle håndfaste beviser for at det er effektivt, før jeg investerede.

[Musiker]

@Leif - Jeg har regnet ud at det koster mig omkring 100kr pr måned.. For et 250L - I starten regnede jeg med 150,- .. Tror de 100kr passer meget godt..

/Henrik

[Carsten]

Zeoliten lader til at være en af de største poster. Men det lader til at den udgift kan sænkes en del.
Godt nok fortæller Pohl ikke præcis hviken form for Zeolit han sælger, og det er der jo nok en årsag til.
Flere andre butikker sælger noget Zeolit som kemisk hedder Clinoptilolith- zeolit.
http://www.naturelemente.de/cgi-bin/sho ... ain&list=0
http://www.tropic-meeresaquaristik.de/e ... lithfilter
Og det jo til en lidt anden pris, end Pohl's 12 euro for en liter.

[Musiker]

Største udgift er nok kullet og Zeobak'en .. Mht kul kan man bruge billigere end KZ's det skal bare sikres den ikke indeholder PO4..

[leifkrarup]

Største udgift er nok kullet og Zeobak'en .. Mht kul kan man bruge billigere end KZ's det skal bare sikres den ikke indeholder PO4..

Zeobak dyrt??....jeg bruger 2 dråber 2x/uge..det kan da ikke koste meget. En lille flaske koster ca. 100 kr. og må da vare i mange måneder.

[Musiker]

Tjae.. Det var bare den første af mine flasker som er ved at være tom hos mig. Så den har holdt siden Maj. Dvs at den har holdt 5 måneder.. 100kr/5 = 20kr pr måned.. Det er da lidt dyrt? Og jeg har i perioder ikke været den bedste til at dosere.. Så det er ikke fordi jeg har brugt for meget

/Henrik

[Musiker]

Det jeg står og skal ud og købe nu og dermed har brugt til mit 250L siden maj er:
1. Zeobak, den mindste flaske (Stort set tom)
2. Kul, 1 pose tom
3. Zeolit, 2 poser (Nu falder intervallerne det skal skiftes med)
4. Zeofood, En del tilbage endnu

[StarF]

ja ok udgiften var ikke så slem så... ku godt overveje det, men i så fald sku det blive med en købt reactor, så man slipper for alt det hjemme fusk

hvor svært var det at starte op med zeovit? som jeg husker skal man starte op på en speciel måde, når akvariet allerede køre?

man kan btw også købe zeovit her: http://www.aquafair.de/index.php/cPath/43_57 mon ikke det virker lige så godt? er jo næppe noget specielt han selv sælger.

[leifkrarup]

Det er meget simpelt at starte op .... den eneste forskel når der er tale om et etableret akvarium er at man starter forsigtigere op for ikke at skade korallerne ved for hurtige ændringer af vandkvaliteten.

[leifkrarup]

man kan btw også købe zeovit her: http://www.aquafair.de/index.php/cPath/43_57 mon ikke det virker lige så godt? er jo næppe noget specielt han selv sælger.

Det var nu ikke lige der jeg ville spare Zeolitter har meget forskellige kemiske egenskaber så det er vigtigt at man får lige netop den type man har brug for.
Jeg tror nok at man kan købe passende zeolitter andre steder, problemet er blot at finde ud af hvilke der er gode nok og for dig vil udgiften til zeosten være ca.200 kr hver 8. uge så du kan måske spare 5-10 kr om måneden ved at købe dem andre steder....er det risikoen værd?

[Carsten]

Vi har kun Pohl's ord for at det er en blanding af 4 forskellige zeolit arter. Og ingen kender det exakte blandingsforhold, hvis der er noget.
Men hvorfor skulle andre arter ikke kunne give samme resultat.
Og hos KZ koster 1 liter Zeolit 12 Euro og hos Aquafair det halve.
Bevares så er udgiften begrænset hvis det kun er er et lille akvarie, men f.eks så skulle jeg bruge 4 liter zeolit.
sådan som jeg læser manualen, så skal halvdelen skiftes efter 6 uger og så fremdeles, det betyder igen at prisen på stenene er 375 kroner hver 3 måned, ialt ca 1500 kroner om året blot for stenene. Der kommer så alle de væsker der skal i, og det er jo ikke så få, og de er bestemt ikke gratis.

[StarF]

husk nu på Pohl har en hvis interesse i, at folk betaler ham for det dyre. Tvivler på der er noget specielt ved det.

[leifkrarup]

husk nu på Pohl har en hvis interesse i, at folk betaler ham for det dyre. Tvivler på der er noget specielt ved det.

I har ret!....alt hvad jeg siger er blot at Zeovitsystemet har kørt i 20 år og der sker en stor vidensdeling og erfaringsudveksling i hele verden, på den måde har man en vis sikkerhed for at de ting man bruger faktisk også gør det de siger de gør.
Jeg vælger så at betale en vis merpris for den viden og sikkerhed der ligger bag.
Hvis nu noget går galt så kan jeg rette op på det indenfor systemet. Hvis jeg bruger andre zeoliter ville jeg ikke vide om det er deres skyld eller om det er doseringerne der skal tweakes....Jeg synes simpelthen ikke at den lille merpris er usikkerheden værd.

[spdiving]

Måske et dumt spørsmål men hvorfor skal ZEOvit sten skiftes ud med nye hvær gang. Kan de ikke bare blive vasket rene igen på en måde og lægges til tøre så alle bakterier dør så de igen kan genbruges i reaktoren ??

Tænkte på at have nogle få poser at skifte imellem men de gamle bliver gjort klar til brug senere.


Steen

[Musiker]

Måske et dumt spørsmål men hvorfor skal ZEOvit sten skiftes ud med nye hvær gang. Kan de ikke bare blive vasket rene igen på en måde og lægges til tøre så alle bakterier dør så de igen kan genbruges i reaktoren ??

Tænkte på at have nogle få poser at skifte imellem men de gamle bliver gjort klar til brug senere.


Steen

Nej en del af virkningen fra dem er at optage stofferne.. Ligesom Rowaphos bliver de mættet på et eller andet tidspunkt og kan ikke længere optage de stoffer man ønsker.
Læste at man kunne få genskabt effekten, men de stoffer som bruges til processen skulle være hammer giftige og ikke noget man kunne bruge i et hjem.
Læste at folk brugte dem som fragment holdere, men jeg har ikke prøvet det endnu...

[leifkrarup]

Måske et dumt spørsmål men hvorfor skal ZEOvit sten skiftes ud med nye hvær gang. Kan de ikke bare blive vasket rene igen på en måde og lægges til tøre så alle bakterier dør så de igen kan genbruges i reaktoren ??

Tænkte på at have nogle få poser at skifte imellem men de gamle bliver gjort klar til brug senere.


Steen

Nej ikke dumt men et oplagt spørgsmål....men NEJ!!! ...og forklaringen findes i den artikel som tråden handler om.

[Hvidtfeldt]

Har lige læst artiklen. Og kan kun give Leif ret, kun brug de zeolitter der er lavet til det, ellers kan det gå galt.
Syntes faktisk at alle der vil starte op med zeovit skulle læse den har artikel da den sætter ting lidt i perspektiv.

[Musiker]

Især den sidste linje summere meget godt op hvad det hele drejer sig om - Zeolit baserede systemer er ikke lettere, billigere eller bedre end flere andre metoder, blot anderledes:

If you are tempted to try your luck with such a system, go ahead. It is a good way to an amazing aquarium. It is not much easier, cheaper, or better than several other methods that are available on the market--it is just different. It will not liberate you from proper and regular maintenance of your tank, and there is no guarantee that your tank will look like the one that made you consider trying this method! Whatever you do, be conscientious and patient. No system can cope with the lack of knowledge, laziness, and impatience of the owner. Happy Reefkeeping!

[Carsten]

Jeg sad lige og kiggede på lidt flere priser på zeovit systemet.
Alle priserne er baseret på Petsupplys priser og mit akvarie. Det indeholder ca 1500 liter vand.

Zeobak= ca 1ml om ugen kr. 9,90
Zeofood= ca. ½ ml om ugen kr. 1,-
Zeostart2= ca 20ml om ugen = kr. 19,-
jern konsentrat= ca 3,5 ml om ugen= kr. 7,-
Kalium/jod/flour= ca 3,5 ml om ugen = kr.12,-
B-balance= ca 100 ml om ugen= kr 57,-
K-balance= ca 100 ml om ugen= kr. 57,-
Stylo pocci= ca 3,5 ml om ugen = kr. 12,-
Zeospur macro= ca 75 ml om ugen= kr. 76,-

Synes nok at det er priser der vil noget, ca 250 kroner om ugen.
Muligvis er der nogle ting som ikke er nødvendige, men hvilke kan jeg ikke gennemskue.

[leifkrarup]

Carsten af disse produkter skal du kun bruge for 30 kr om ugen for at køre Zeovit....mange af de andre ting er overflødige hvis du skifter de 5% vand om ugen som er forudsætningen for at køre Zeovit, og bruger en af de anbefalede saltblandinger....blandt disse KZ´s egen Reefers Best Salt som er ca. 50 kr dyrere end de fleste andre mærker.
Alle øvrige er produkter som man kan vælge prøve at tweake korallerne med hvis man har lyst.