# Oase Biomaster… thinking of buying and need some advice



## CJM70 (30 Nov 2021)

Hi everyone I’m about to buy one of these filters as I have seen and reviewed from here to Timbuktu and it seems that they are well received. One of the things I really like the idea of is the pre-filter cartridge. Up till now I had always thought that filter media should be washed in aquarium water. But many of the reviews of this filter state that you can wash the pre-filter sponges in tapwater because they are purely mechanical. I totally understand the difference between mechanical biological and chemical filtration, however I still have a concern because once rinsed in tapwater they will contain droplets of water that has not been dechlorinated.

Surely even that small amount of non-dechlorinated water has the potential to damage some of the bacteria in your filter? Or is it literally the case that it is so little it will not have any effect? I guess I am old school and have always been told that even mechanical filtration should be rinsed in tapwater and as a consequence I have always done this at the same time as water changes and used the dirty water change water for cleaning any filter media in.

If anyone who has one of these filters can clarify the situation I would be most grateful. I have to say the only reason I am questioning my knowledge is that I have seen some very prominent aquascapers State in the reviews, that the pre-filter sponges need not be washed in tank water. I realise that these guys have extensive knowledge and experience with these products, so I am just wondering if I can get some clarity on this matter before I potentially caused any damage to the bacteria in the rest of my filter once it is up and running.

Also whilst I am asking about this filter I note that some people have claimed that there was a lot of air bubbles causing some noise and I’m just wondering if that was something that the manufacturer has resolved now or if there is an easy fix?

Thanks for all your help.


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## Courtneybst (30 Nov 2021)

CJM70 said:


> But many of the reviews of this filter state that you can wash the pre-filter sponges in tapwater because they are purely mechanical


I do this every week with no ill effects. To be honest, even if I did absolutey murder all the bacteria in the pre filter sponge, there's still 6 trays worth (at least in the 850) of media which the bacteria is still clinging too. There's also tons more bacteria in the planted tank itself. I wouldn't let that worry you at all.


CJM70 said:


> Or is it literally the case that it is so little it will not have any effect?


It's my understanding that this bacteria would need to be exposed to chlorine for a sustained period to really have an impact. Even if this isn't the case my previous point remains.


CJM70 said:


> I’m just wondering if that was something that the manufacturer has resolved now or if there is an easy fix?


It doesn't appear to be resolved. Some have claimed to have solved their issues with a few tweaks but the ones with mine persist. For me, the pre filter and built in heater at that price point is the trade-off I'm making for said issues.


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## Wookii (1 Dec 2021)

CJM70 said:


> Hi everyone I’m about to buy one of these filters as I have seen and reviewed from here to Timbuktu and it seems that they are well received. One of the things I really like the idea of is the pre-filter cartridge. Up till now I had always thought that filter media should be washed in aquarium water. But many of the reviews of this filter state that you can wash the pre-filter sponges in tapwater because they are purely mechanical. I totally understand the difference between mechanical biological and chemical filtration, however I still have a concern because once rinsed in tapwater they will contain droplets of water that has not been dechlorinated.
> 
> Surely even that small amount of non-dechlorinated water has the potential to damage some of the bacteria in your filter? Or is it literally the case that it is so little it will not have any effect? I guess I am old school and have always been told that even mechanical filtration should be rinsed in tapwater and as a consequence I have always done this at the same time as water changes and used the dirty water change water for cleaning any filter media in.
> 
> ...



The pre-filter sponges are for mechanical filtration only, the sponges and media in the main filter housing are for biological filtration, so the pre-filter sponges can be washed in tap water without issue, and should be to get them thoroughly clean.

The tiny trace amount of chlorine that may be left in the sponges will have absolutely no impact in the bacterial assemblage, the concentration will be far too dilute to have any effect. That said, I would recommend filling the pre-filter cartridge with water before placing back in the filter, as it a lot easier to prime with that full of water than air, and will usually start running straight away without using the priming button. Adding the water gives you the opportunity to add a drop or two of Prime which will immediately eliminate any chlorine anyway.


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## CJM70 (1 Dec 2021)

Wookii said:


> The pre-filter sponges are for mechanical filtration only, the sponges and media in the main filter housing are for biological filtration, so the pre-filter sponges can be washed in tap water without issue, and should be to get them thoroughly clean.
> 
> The tiny trace amount of chlorine that may be left in the sponges will have absolutely no impact in the bacterial assemblage, the concentration will be far too dilute to have any effect. That said, I would recommend filling the pre-filter cartridge with water before placing back in the filter, as it a lot easier to prime with that full of water than air, and will usually start running straight away without using the priming button. Adding the water gives you the opportunity to add a drop or two of Prime which will immediately eliminate any chlorine anyway.


Thanks for putting my mind at rest. It was the trace amount of chlorine that was niggling me.  But doing it your way by filling the pre-filter chamber with water and a few drops of prime is an excellent solution.   🙏🏻


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## Wookii (1 Dec 2021)

CJM70 said:


> Thanks for putting my mind at rest. It was the trace amount of chlorine that was niggling me.  But doing it your way by filling the pre-filter chamber with water and a few drops of prime is an excellent solution.   🙏🏻



The other thing I forgot to mention, is I use two sets of pre-filter sponges also, so I can can get the filter switched back on straight away. So I remove the dirty ones, put on the dry clean ones, fill the pre-filter chamber and put it back in the filter and switch the filter back on. Then I go off and wash the dirty pre-filter sponges, and leave them to dry ready for the next cleaning session. So the drying process would also eliminate the chlorine.


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## CJM70 (1 Dec 2021)

Wookii said:


> The other thing I forgot to mention, is I use two sets of pre-filter sponges also, so I can can get the filter switched back on straight away. So I remove the dirty ones, put on the dry clean ones, fill the pre-filter chamber and put it back in the filter and switch the filter back on. Then I go off and wash the dirty pre-filter sponges, and leave them to dry ready for the next cleaning session. So the drying process would also eliminate the chlorine.


Brilliant Wookii , that makes perfect sense and is a great idea. What are your thoughts on using impart some of the carbon impregnated pre-filter sponges that the manufacturer office?


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## Wookii (1 Dec 2021)

CJM70 said:


> Brilliant Wookii , that makes perfect sense and is a great idea. What are your thoughts on using impart some of the carbon impregnated pre-filter sponges that the manufacturer office?



They're likely a waste of time and money to be honest. If you want to use activated carbon during tank start-up, a proper granulated one in a mesh bag in the filter is a better bet, though the benefits of using activated carbon at all are a matter of debate.


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## CJM70 (1 Dec 2021)

Wookii said:


> They're likely a waste of time and money to be honest. If you want to use activated carbon during tank start-up, a proper granulated one in a mesh bag in the filter is a better bet, though the benefits of using activated carbon at all are a matter of debate.


That makes sense I would expect to get much more carbon surface area using granulated carbon in a filter bag then simply impregnated in foam.

whilst on the subject of truth or myth, what is your opinion on products such as twin star or chihiros aquarium sterilisers. You know the ones that are supposed to kill algae promote plant growth and protect fish stock.


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