The Great Mechanical Filtration Experiment

[Gold Fish]

Hi Bradders,
I already done this test.
I have changed all my media in my filter with sponge similar to your blue sponge in the bio trays. With that, the filter worked fine until it started eliminating long stripes of detritus. Not many and the fish enjoy to eat them. Still I didn't like them and now I have a final layer of sponge similar with your orange Oase last sponge. That is doing a good job in collecting all of that floating stuff but then it's becoming clogged as fast as in the original setup.
Please keep in mind that all this happened having a prefilter fitted on top of the intake which stopped all big stuff to get in the canister and was weekly cleaned with the water changes.
So, my advice for you is:
In order to be able to touch less your canister, use those new 10 ppi prefilter sponges, but add as Darrel was saying, a minimum 30 ppi prefilter on the intake. That will be easy to be weekly clean with the water charges. This way you will not need to clean the prefilter in the canister so often but you will still need to give it a general clean every 6 months as before.
If you are not going to use a prefilter on the intake, then you will need to clean the canister prefilter every 2 weeks and open the trays every 4 to 6 months...
Good luck with your test.

 

[Bradders]

Thank you for the insights @Gold Fish ! A couple of questions, so I understand.

I have changed all my media in my filter with sponge similar to your blue sponge in the bio trays. With that, the filter worked fine until it started eliminating long stripes of detritus. Not many and the fish enjoy to eat them. Still I didn't like them and now I have a final layer of sponge similar with your orange Oase last sponge. That is doing a good job in collecting all of that floating stuff but then it's becoming clogged as fast as in the original setup.

I assume you dont have an Oase filter? That correct? Also, what do you mean 'long stripes of detritus'?

I have a final layer of sponge similar with your orange Oase last sponge. That is doing a good job in collecting all of that floating stuff but then it's becoming clogged as fast as in the original setup.

I am working on a theory that filtration that gets clogged in relatively short spaces of time is due to it not being able to handle the load - well, not without cleaning periodically to restore that load capability. As an example, my Oase 250 is now 8 months old and the pre-filter was cleaned weekly when using 45PPI foam. However, an inspection over this weekend showed that the 2 x 20PPI foam and 1 x 30PPI foam in the internal unit was not clogged nor dirty - just a biofilm present. In short, still no need to clean. It would be interesting to understand your bio-load in proportion to your filtration to get an idea if you have any time.

 

[Gold Fish]

Bradders,
No I don't have an Oase filter. Is an Eheim.
When you clean the filter, your water becomes dirty, but if you look closer you can see particles floating in it. Put 10 of them in a chain and you have my floating strings.
Regarding your filter, it will clog where is your finest filter. That can be the orange sponge or before at the matrix front face.(bottom of the lower matrix tray).
And finally, yes, it all depends on the bio-load and filter capacity.

 

[Bradders]

Regarding your filter, it will clog where is your finest filter. That can be the orange sponge or before at the matrix front face.(bottom of the lower matrix tray).

Thanks, Gold Fish. Yes, the current experiment is as below, in terms of flow direction. I am not going above 30PPI foam.

1. Pre-filter: 10PPI Foam
2. Tray 1: HEL-X13 Media
3. Tray 2: 20PP1 Foam
4. Tray 3: 20 PPI Foam
5. Tray 4: 30 PPI Foam

And finally, yes, it all depends on the bio-load and filter capacity.

I have done some calculations on bio-load, and 1 Oase Filter is around 55% capacity, just based on fish waste produced etc. Now, if my theory is correct, they should not clog too quickly - which seems to be the direction I am going at the moment, but it's too early to tell with the recent change of the pre-filter from 45PPI down to 10PPI. Effectively, I have 'opened the gates of hell' and allowed more detritus into the main unit with all the bio-media. It will either deal with it, or it will start to clog as it cannot deal with it. I am also keeping a close eye on water clarity.

 

[ElleDee]

It will either deal with it, or it will start to clog as it cannot deal with it. I am also keeping a close eye on water clarity.

So, you are positing that if there's enough filtration capacity there won't be much residual mass left over to clog the canister? Just checking that I'm getting the hypothesis here.

 

[fredi]

I am working on a theory that filtration that gets clogged in relatively short spaces of time is due to it not being able to handle the load

Completely agree with this, with the proviso that the media used is suitable (not too fine), I think that a “sensible” balance between area and flow is required to maximise the efficacy of the filter

 

[Bradders]

So, you are positing that if there's enough filtration capacity there won't be much residual mass left over to clog the canister? Just checking that I'm getting the hypothesis here.

Correct, that is what I am aiming at. According to my math, the amount of plastic biomedia and foam should deal with 154 grams of fish with very clear water. I only have 80-100 grams of fish in my aquarium, which means it should (if this works) have no problems handling the load and clog very rarely. (Again, the theory is if you HAVE to clean your bio media every 3 weeks because it's clogged, then it can't handle the load).

Completely agree with this, with the proviso that the media used is suitable (not too fine), I think that a “sensible” balance between area and flow is required to maximise the efficacy of the filter

I think (down to the basic math) I have the surface area and nothing is too fine, but flow is something I am also keeping an eye on. My filter only turns over 4-5 times the tank volume each hour. I have a good amount of surface agitation to assist with oxygen gas exchange but I agree that oxygen needs to keep getting into the closed-system canister.

 

[fredi]

Correct, that is what I am aiming at. According to my math, the amount of plastic biomedia and foam should deal with 154 grams of fish with very clear water. I only have 80-100 grams of fish in my aquarium, which means it should (if this works) have no problems handling the load and clog very rarely. (Again, the theory is if you HAVE to clean your bio media every 3 weeks because it's clogged, then it can't handle the load).

I think (down to the basic math) I have the surface area and nothing is too fine, but flow is something I am also keeping an eye on. My filter only turns over 4-5 times the tank volume each hour. I have a good amount of surface agitation to assist with oxygen gas exchange but I agree that oxygen needs to keep getting into the closed-system canister.

I think that you will find that “fine” media works ok initially(with sufficiently high flow), then clogs and efficiency drops off
Whereas “course” media lacks the surface area which “fine” media has, but (providing that flow is ok), maintains a more consistent efficiency, I binned my fine foam, I do use filter floss, although am getting through it quite quickly due to Panaque’s creating sawdust 😩

 

[ElleDee]

Correct, that is what I am aiming at. According to my math, the amount of plastic biomedia and foam should deal with 154 grams of fish with very clear water. I only have 80-100 grams of fish in my aquarium, which means it should (if this works) have no problems handling the load and clog very rarely. (Again, the theory is if you HAVE to clean your bio media every 3 weeks because it's clogged, then it can't handle the load).

I think (down to the basic math) I have the surface area and nothing is too fine, but flow is something I am also keeping an eye on. My filter only turns over 4-5 times the tank volume each hour. I have a good amount of surface agitation to assist with oxygen gas exchange but I agree that oxygen needs to keep getting into the closed-system canister.

Interesting. I always assumed that stuff would be leftover after the filter microbes did their thing; it would be transformed, but still large enough to clog a static filter. I don't really know though, I'm imagining it works like organic matter breaking down in soil, but it's not quite the same thing. I know you'll let us know.

 

[Gold Fish]

Thanks, Gold Fish. Yes, the current experiment is as below, in terms of flow direction. I am not going above 30PPI foam.

1. Pre-filter: 10PPI Foam
2. Tray 1: HEL-X13 Media
3. Tray 2: 20PP1 Foam
4. Tray 3: 20 PPI Foam
5. Tray 4: 30 PPI Foam

I have done some calculations on bio-load, and 1 Oase Filter is around 55% capacity, just based on fish waste produced etc. Now, if my theory is correct, they should not clog too quickly - which seems to be the direction I am going at the moment, but it's too early to tell with the recent change of the pre-filter from 45PPI down to 10PPI. Effectively, I have 'opened the gates of hell' and allowed more detritus into the main unit with all the bio-media. It will either deal with it, or it will start to clog as it cannot deal with it. I am also keeping a close eye on water clarity.

Using that arrangement, my bet is as follows:
You will end up cleaning the prefilter 2 or 3 weeks intervals because of plant materials clogging.
In 4 to 6 months you will need to clean the 30 ppi foam which will be clogged with detritus collected from the biological filtration.
I'm looking forward to see if my guess is close. 🤣😂🤣

 

[Bradders]

Interesting. I always assumed that stuff would be leftover after the filter microbes did their thing; it would be transformed, but still large enough to clog a static filter. I don't really know though, I'm imagining it works like organic matter breaking down in soil, but it's not quite the same thing. I know you'll let us know.

I'm looking forward to see if my guess is close. 🤣😂🤣

Yes, indeed, I will defo let you know. And I am also looking forward to finding out!

 

[hypnogogia]

Little update for you @Bradders. I have 10ppi pre filters attached to the filter intake, 30ppi on the filter pre filter. The filter itself has 3 trays of K1 micro media and 2 trays of 30ppi foams. After about 6 months I opened it up, and despite cleaning pre filters regularly, the inside was full of gunge, explaining why the filter flow had substantially reduced. I’m not sure using only 10ppi as a pre filter is the way to go.

 

[Bradders]

Little update for you @Bradders. I have 10ppi pre filters attached to the filter intake, 30ppi on the filter pre filter. The filter itself has 3 trays of K1 micro media and 2 trays of 30ppi foams. After about 6 months I opened it up, and despite cleaning pre filters regularly, the inside was full of gunge, explaining why the filter flow had substantially reduced. I’m not sure using only 10ppi as a pre filter is the way to go.

Very interesting.

So (as a comparison, and why I am trying to progress this little rabbit hole of a project!), what do you think it means that for eight months, I have used the standard Oase 250 configuration (mix of 30/45 PPI pre-filters, 1 Tray HEL-X13, 2 Trays 20PPI Foam and 1 Tray 30 PPI foam), and my last check shows that none of the inner trays were dirty/clogged and my flow has remained at the 500 - 600 L/per hour mark since it was purchased? (Bar pre-filler cleans).

 

[hypnogogia]

Very interesting.

So (as a comparison, and why I am trying to progress this little rabbit hole of a project!), what do you think it means that for eight months, I have used the standard Oase 250 configuration (mix of 30/45 PPI pre-filters, 1 Tray HEL-X13, 2 Trays 20PPI Foam and 1 Tray 30 PPI foam), and my last check shows that none of the inner trays were dirty/clogged and my flow has remained at the 500 - 600 L/per hour mark since it was purchased? (Bar pre-filler cleans).

I think it might be an aging thing. When I first changed to the bio media I have now (from bio home) it would happily run for 6 months, and when I opened it up it was clean. Not this time though. It’s almost like it slowly approaches a tipping point. Current media has been in for about 18 months.

 

[Bradders]

I think it might be an aging thing. When I first changed to the bio media I have now (from bio home) it would happily run for 6 months, and when I opened it up it was clean. Not this time though. It’s almost like it slowly approaches a tipping point. Current media has been in for about 18 months.

That is interesting. So your working theory is the age of the foam itself after prolonged use? i.e. the older it is, the less it will effectively deal with the load before clogging?

That is implying (if we are talking about the foam) that one of three things could potentially be happening.

• The foam surface area is breaking down, meaning there is less of it, so therefore gets clogged quicker.
• The bio-load in the aquarium has changed (increased) over the 18 months placing more load and therefore clogging quicker.
• A mixture of both the above.

 

[hypnogogia]

That is interesting. So your working theory is the age of the foam itself after prolonged use? i.e. the older it is, the less it will effectively deal with the load before clogging?

That is implying (if we are talking about the foam) that one of three things could potentially be happening.

• The foam surface area is breaking down, meaning there is less of it, so therefore gets clogged quicker.
• The bio-load in the aquarium has changed (increased) over the 18 months placing more load and therefore clogging quicker.
• A mixture of both the above.

There’s a 3rd option, which is that the biofilm is getting thicker and in my gentle cleaning in aquarium water hasn’t been removed (as intended) until eventually it’s just got too much. The gunk wasn’t just in the foams, it was also in the K1.

 

[Bradders]

There’s a 3rd option, which is that the biofilm is getting thicker and in my gentle cleaning in aquarium water hasn’t been removed (as intended) until eventually it’s just got too much. The gunk wasn’t just in the foams, it was also in the K1.

Yeah, I was thinking about that as well. It's too much hassle, but the only way to prove that would be to replace just one foam with a new one (i.e. keeping all the other bio-media untouched) and see if that one new foam does not clog at the same rate. But that depends on your loading and how much it already relies on that foam being populated with bacteria.

 

[HopefulBrit]

Well, some of us are bored, so it's time to start tinkering. (Fed up with spreadsheets, so moving on to a practicable). 🙂

Hey Bradders,

Would be really interested to know if there's any follow up to this experiment.​

​

Best,
L.

 

[Gold Fish]

Hey Bradders,

Any updates on your experiment?
I have cleaned mine once since then. The10 ppm sponge was OK, only the last 30 ppm sponge was "clogged" with the collected mulm. I give it a quick squeeze. It was still brown, not blue as the original colour and just a quick shake to the 10 ppm sponges. Have them all back in my experience 250 and now 3 months later is still going strong.
Don't forget, I have a sponge over the strainer in the tank which gets cleaned weekly with the water changes. That stops all the baby shrimps and th big particles to get in the filter.
How about you?

 

[Bradders]

Would be really interested to know if there's any follow up to this experiment.​

Any updates on your experiment?

Really sorry everyone, I forgot to continue and come back to this!!

OK, so what have I don't in that time? (One thing is for sure, and that is enrage @dw1305 by using my filter as a syphon! 😛 )

Without the scientific approach to record this, here is what I done (+reminders) and my views:

• I am always conscious of theoretical load capacity of my bio-media - calculated by fish metabolic weight verses the surface areas of the bio-media.
• My maturist Oase 250 has never had more than a theoretical capacity of 50% fish loading. (e.g. surface area supports 250g of fish, I never has more than 125g of fish).
• The biomedia in a main filter unit (20PPI) that has never been cleaned since June 2023. Inspection shows discoloration, but certainly not clogged or full of detritus.
• Tested pre-filter of 10PPI for last 3-4 months, has not seemed to affect anything. Inspection of foam shows little negative progression from the point above, and any flow difference is not noticeable.
• Water remains crystal clear, fish deaths remain very low and infrequent. (Blackwater fish have remained alive for entire 19 months). So I feel the filter is still keeping the aquarium healthy despite no thorough cleaning of the 20PPI biomedia.

So what does this say to me?

1. At a technology level, there does seem to be something positive about 'over-filtration'. e.g. (and stating the bleeding obvious!) not having too much demand on your filter from loading can extended the periods between cleaning.
2. Extended periods between cleaning means less risk of disturbing the BB in the biomedia. (Now, there is some research that shows cleaning very mature biomedia does not kill the BB, even in chlorinated water. But lets leave that for now).
3. Although the 10PPI experiment has only run for 100 days or so, there was not a notable impact on flow, decrease in observable water quality or observable increase of detritus/clogging within the 20PPI biomedia.