# Mechanical and Biological filtration in different filters.



## pseudodiego (22 Dec 2021)

Hi everyone.

One doubt. I'm planning to have an external filter with only biological filtration, and one hang on filter with mechanical filtration, as that way I'll be able to clean the sponges weekly in the water changes with ease.

Is there any reason not to do it?

Thanks.


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## Konsa (22 Dec 2021)

Hi
If you are CO2 user the hang on filter will degass more CO2 so you will need to adjust your injection rate.
No other downsides.
I use fairly large prefilter sponges ( cleaned werkly)on my canisters so most of the muck is caught in those but due to having messy fish had small internal filter with sponge to help me polish the water.It works but is extra sth to try to hide.
I rarely clean my canisters too.Maybe once an year or so and they are always spotless
Regards Konstantin


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## Matti (22 Dec 2021)

Sounds a bit complicated, I would have just one filter.
What kind of filter, it depends. If you want to keep it simple, a Matten filter.  You clean it once a year, or once in two years.
In the end, this is a very simple hobby.


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## pseudodiego (22 Dec 2021)

Matti said:


> Sounds a bit complicated, I would have just one filter.
> What kind of filter, it depends. If you want to keep it simple, a Matten filter.  You clean it once a year, or once in two years.
> In the end, this is a very simple hobby.


Complicated why? 

I asked because I already have those two filters, I willuse them both anyway, only difference is if I separate the mechanical and biological filtration or if the two filters have both.


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## Konsa (22 Dec 2021)

Hi
Biological and mechanical filtration will occur in both filters anyway. You can separate different media in both filters but thats about it.You don't really want to have a filter that is packed with the so called biological media without any form of pre filter to it  (to keep away the majority of the muck )or you will have to clean it fairly often.
Have a read through this and the links in it.





						Is expensive bio media worth it?
					

Could a heavily planted tank take the main role of biological filtration to the point any other filtration you have would end up becoming mechanical?  Yes, I think so. Plants and the substrate. I can see that happen if you have lots of plants relative to livestock and excellent flow throughout...



					www.ukaps.org
				



Regards Konstantin


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## Gold Fish (22 Dec 2021)

If you let the water carrying particles (fish poo, leafs, other stuff) into the external filter, you will have mechanical filtration in it. The only question is how soon it will require to be cleaned. 
Let me give you another option: have a fine prefilter on the intake (like a shrimp guard or fine sponge) and that it will stop staf going in the filter. You will still need to clean that prefilter weekly and hoover the tank bottom where all the rubbish will be collected. 
In order for the hang on filter to collect that rubbish, you will need to ensure a water current which will push al that toward the correct intake.


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## Nick potts (22 Dec 2021)

As above really. Both filters are going to be colonised by bacteria for bio filtration, and both are going to trap debris.

Your best option is going to be to add mechanical filtration to both and just change it often, if you left the external with just bio and no mech and didn't clean it, it would soon clog up and reduce efficiency.


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## CJM70 (23 Dec 2021)

I think the point here is that you want the filtration to be selective, but the filters cannot be so. It’s not like the hang on will just select the dirty water to mechanically remove particular waste, and the canister will then JUST do biological filtration. Both will do both. Which means you will still have to clean both filters, but in fact will have more work to do as a result. The only reason to use both really is if you have insufficient flow and require more water movement, but as mentioned above, if using CO2, you will be degassing some of it.
It would enable a more “educated” response to know what filters you refer to, the size of your tank, the amount of planting, and the bio load in terms of fish etc.


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## erwin123 (23 Dec 2021)

all this sounds awfully familiar to those doing product design and development. we should identify the needs first and apply the 

Needs
(1) Biological filtration - keep fish from being poisoned - (Threshold feature - customer doesn't really care how its done whether by HOB or canister, as long as its done))
(2) Mechanical filtration - keep water clear to enjoy the tank more (Threshold feature -customer doesn't really care how its done whether by HOB or canister, as long as its done)
(3) Don't like cleaning filters - idea of a perfect canister filter is one that is never opened. (if product has this feature it will delights the customer)

Customer needs 2 threshold features to be satisfied but will be truly delighted only if he never needs to open up the canister filter.

I guess that led to the development of the Oase Biomaster with separate removable prefilter. The Fluval 07 series went a different direction and decided on a super-huge prefilter compartment that can take in a lot of dirt before it ever gets clogged, so you don't have to clean it as often.  Each has pros and cons, the Oase has a huge footprint to accommodate its various features, the Fluval 07 is much more compact.  Customer has to choose - easy to remove prefilter that has to be cleaned a bit more regularly since its smaller, or a huge prefilter where you still have to open the canister, but the interval is longer.


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## pseudodiego (23 Dec 2021)

CJM70 said:


> I think the point here is that you want the filtration to be selective, but the filters cannot be so. It’s not like the hang on will just select the dirty water to mechanically remove particular waste, and the canister will then JUST do biological filtration. Both will do both. Which means you will still have to clean both filters, but in fact will have more work to do as a result. The only reason to use both really is if you have insufficient flow and require more water movement, but as mentioned above, if using CO2, you will be degassing some of it.
> It would enable a more “educated” response to know what filters you refer to, the size of your tank, the amount of planting, and the bio load in terms of fish etc.


It will be a 75 liters tank (60x35x35) , heavily planted with CO2, intense light and ferts.

Stocking will be 10-15 nano fish(possibly Microrasboras galaxy), 5 clithon snails, 10 amano shrimp and maybe 6 otocinclus if there is enough algae in the tank.

The filters are an aquaclear 30, and a Sera Fil Bioactive 130. One of the plus of using the aquaclear filter is that I can place the heater inside it, as it fits.


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## pseudodiego (23 Dec 2021)

erwin123 said:


> all this sounds awfully familiar to those doing product design and development. we should identify the needs first and apply the Kano Model
> 
> Needs
> (1) Biological filtration - keep fish from being poisoned - (Threshold feature - customer doesn't really care how its done whether by HOB or canister, as long as its done))
> ...


Good analisis, thanks. But I don't want to buy other filters as I already have those two. If isn't possible to separate biological and mechanical filtration I'll have to settle to cleaning both filters.


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## jaypeecee (23 Dec 2021)

erwin123 said:


> all this sounds awfully familiar to those doing product design and development. we should identify the needs first and apply the Kano Model


Hi @erwin123 

There seems to be a problem with the link above - 'Page Not Found' Error.

JPC


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## Nick potts (23 Dec 2021)

pseudodiego said:


> Good analisis, thanks. But I don't want to buy other filters as I already have those two. If isn't possible to separate biological and mechanical filtration I'll have to settle to cleaning both filters.


I think you are going to need both filters, or to add some extra flow with a powerhead etc IMO.

If you wanted to cut down on the amount you need to clean/open the external filter you could add a large prefilter sponge to the intake and just clean that as needed.



jaypeecee said:


> Hi @erwin123
> 
> There seems to be a problem with the link above - 'Page Not Found' Error.
> 
> JPC



"The Kano Model (pronounced “Kah-no”) is an approach to prioritizing features on a product roadmap based on the degree to which they are likely to satisfy customers"

That's about the gist of it


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## pseudodiego (23 Dec 2021)

Nick potts said:


> I think you are going to need both filters, or to add some extra flow with a powerhead etc IMO.
> 
> 
> 
> ...


As another option I have an aquaclear 70, but the flow of that one is really strong and I'm not sure if it would be simply too much for a 75 liters.


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## Nick potts (23 Dec 2021)

pseudodiego said:


> As another option I have an aquaclear 70, but the flow of that one is really strong and I'm not sure if it would be simply too much for a 75 liters.



I'd give it a try, I am of the opinion that the more flow the better, I have more flow on a tank of half the volume. Also, the hang on filters flow tends to be quite diffuse so should be fine.


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## CJM70 (23 Dec 2021)

pseudodiego said:


> It will be a 75 liters tank (60x35x35) , heavily planted with CO2, intense light and ferts.
> 
> Stocking will be 10-15 nano fish(possibly Microrasboras galaxy), 5 clithon snails, 10 amano shrimp and maybe 6 otocinclus if there is enough algae in the tank.
> 
> The filters are an aquaclear 30, and a Sera Fil Bioactive 130. One of the plus of using the aquaclear filter is that I can place the heater inside it, as it fits.


Thanks for the information it sounds like it’s going to be an interesting tank to see.

Nice choice of fish and that stocking level should be fine with fish that size though I’m not sure that there will be enough food for the shrimp and ottos after the tank is settled.

I’m also concerned about putting a heater into a filter that is not specifically designed for it, or am I mistaken and there is a specific chamber to hold a heater in the filter you mentioned? My concern is when the heater is on, the plastic off the filter may not be of a suitable grade to cope with direct heat. However if you can fix the heater using suction cups and a heater bracket then it might be safe.

The sera is a nice filter. But I would still advise against putting only biological media in it. There would be no harm in putting some medium filter foam in it. I think you said you wanted to do this to avoid having to open up the canister too often, but you will have to do this in any case because the buyer media will take a lot more mechanical clubbing in my opinion.  Nick Potts made the suggestion of using a pre-filter foam on the intake of the canister filter, and this is a fair suggestion. However the tank you have is relatively small and any extra equipment placed inside the tank will reduce the options you have for scaping it. I recall putting an Eheim pre-filter on the intake of a 3 foot tank I had once and I hated it because it encroached on the space I could use for better purpose.  But everyone has different priorities and you could of course hide it with hard scape or plants.

if it were my choice, I would either sell both filters, or use them for other purposes. And then I would look to buy something like an Oase biomaster thermo 350 for that tank. This filter has two advantages. Firstly it has a pre-filter chamber that you can change on the fly without having to open the main compartment of the canister. Many users both on here and across YouTube and other forums have reported that using this method means they can leave the main canister zone maintenance free for long periods of time.  The other benefit is that it also has a built-in heater which you can either use or not as the filter comes with a cap to replace the heater if it is not needed to be used.  

The other alternative that you might consider is to not use the HOB filter, but instead go for something like an Oase filtosmart thermo 100/200.  These are small external canister filters which again give you the option of having built-in heaters.  They will give you additional flow but because of the return method, they would not necessarily cause additional degassing of your CO2.

Remember you don’t necessarily have to buy brand-new. I managed to pick up the external canister filter I mentioned above, in immaculate condition, for half the price most retailers charge.  
hope this information is helpful, and remember at the end of the day regardless of what advice you get you need to make the decision that you feel makes you most comfortable and will suit your situation the best. Keep us posted and don’t forget to do a new tank thread when you get this going.


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## pseudodiego (23 Dec 2021)

CJM70 said:


> Thanks for the information it sounds like it’s going to be an interesting tank to see.
> 
> Nice choice of fish and that stocking level should be fine with fish that size though I’m not sure that there will be enough food for the shrimp and ottos after the tank is settled.
> 
> ...


Thanks for the ideas. About the heater, I tested it beforehand. The heat doesn't affect the plastic of the aquaclear at all.

I think I'll drop both filters and use the Aquaclear 70 that I mentioned. I just watched some videos about it and the flow can be reduced if is indeed too much.


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## hypnogogia (23 Dec 2021)

You’ll always need a mechanical pre-filter before the biological media, so you are stuck with opening and cleaning both filters.


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## sparkyweasel (23 Dec 2021)

jaypeecee said:


> Hi @erwin123
> 
> There seems to be a problem with the link above - 'Page Not Found' Error.
> 
> JPC


Try this;
Kano


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## Nick potts (23 Dec 2021)

pseudodiego said:


> It will be a 75 liters tank (60x35x35) , heavily planted with CO2, intense light and ferts.





pseudodiego said:


> I think I'll drop both filters and use the Aquaclear 70 that I mentioned. I just watched some videos about it and the flow can be reduced if is indeed too much.



I think you may struggle with the aquaclear and CO2, only because of how these filters return the water, rather than a flow across the tank like a standard filter it pours down into the tank, this means the circulation of co2 might not be great. I would be sticking with the external as well.


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## pseudodiego (24 Dec 2021)

Nick potts said:


> I think you may struggle with the aquaclear and CO2, only because of how these filters return the water, rather than a flow across the tank like a standard filter it pours down into the tank, this means the circulation of co2 might not be great. I would be sticking with the external as well.


It seems to be doable.



That's a 80 liters tank that seems to be running just with an Aquaclear 30. I guess the secret is to always have a high level water. So the CO2 doesn't flunctuate too much.


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## Nick potts (24 Dec 2021)

pseudodiego said:


> It seems to be doable.
> 
> 
> 
> That's a 80 liters tank that seems to be running just with an Aquaclear 30. I guess the secret is to always have a high level water. So the CO2 doesn't flunctuate too much.




The secret in the case of the video above is it is Filipe Oliveira  He understands aquarium plants and husbandry on a very high level. He could probably run a successful tank using a candle lol

I am not saying it's not possible, just that these filters are harder to work with than a typical external filter or filter with a traditional output. You'll also notice he is using a surface skimmer which helps with flow


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## pseudodiego (27 Dec 2021)

Well, my girlfriend bought me the Oase Biomaster 250 thermo for christmas, so problem solved.


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