Oxygen levels required

[Soilwork]

Hi all.

What are the minimal oxygen levels required for nitrifying bacteria to a) nitrify and b) survive/reproduce.

What are the minimum levels of DO required for fish/shrimp etc (I know this will vary but in general)

What are the forums thoughts on bottled bacteria products. Is it true that true nitrifying bacteria can go dormant with low levels of oxygen whilst being shelved?

Dr Tim Hanovec (founder of Dr Tims aquatics) alludes to this as being what happens.

Thanks
Craig.

 

[dw1305]

Hi all,

...What are the minimal oxygen levels required for nitrifying bacteria to a) nitrify and b) survive/reproduce.........What are the forums thoughts on bottled bacteria products. Is it true that true nitrifying bacteria can go dormant with low levels of oxygen whilst being shelved? Dr Tim Hanovec (founder of Dr Tims aquatics) alludes to this as being what happens...

I think these are very relevant questions, and this is discussed, to some degree in the <"Best way to cycle a second...">.

I think the answer is that nitrification is likely to occur at lower levels of dissolved oxygen than was originally thought, mainly because the <"organisms involved are Archaeae">. The work on Aquarium filters is reported in <"Aquarium Nitrification Revisited: Thaumarchaeota Are the Dominant Ammonia Oxidizers in Freshwater Aquarium Biofilters">.

The real problem is that, most of what, we thought, we knew about the ammonia oxidising organisms (AOO), isn't actually true for aquariums. Earlier work (and bacterial supplements) utilised Nitrosomonas, Nitrobacter and Nitrospira based on work originally done on sewage treatment etc. Subsequent research has shown that only Nitrospira (which was thought to convert nitrite (NO2) to nitrate (NO3)) is present, and that Nitrospira can also <"directly oxidise ammonia (NH3) to NO3">.

Doctor Hovanec's comments on changes in our knowledge about nitrifying organisms are here: <"Bacteria revealed">, and it is well worth a read. His scientific papers are <"here">, and his products page is here: <"DrTim's Aquatics">, where you can buy the latest incarnation of <"One and Only: Live Nitrifying Bacteria">, which doesn't need to be refrigerated.

What are the minimum levels of DO required for fish/shrimp etc (I know this will vary but in general)

I'm not sure any-one will know. You can make assumptions based on the natural habitat of fish, rheophilic fish from cooler waters are likely to be the most vulnerable to low oxygen levels. There is more discussion in <"Aeration and dissolved oxygen....">

Due to the relationship between temperature and gas solubility (as temperature rises solubility falls) warm water that is 100% saturated with oxygen may not not contain enough dissolved oxygen (in mg/l) to sustain some fish. There is a chart to work out the relationship between temperature and DO in <"Twinstar..what is it: page 34">.

There are minimum figures for the organisms grown in commercial aquaculture, you could assume that Atlantic Salmon (Salmo salar) would be about the most sensitive, and it needs <70% DO levels (at 16oC) for growth, and the hypoxia tolerance threshold is 47% O2.

cheers Darrel

 

[zozo]

What are the forums thoughts on bottled bacteria products.

Once did read an article at a pond community about starting up ponds with bacteria, (not in english) where sevral products were tested.. The gel products performed the best, the powder and liquid products did nearly add nothing but ammonia and nitrite and were considered a waste of money..

In areas where no chloramine is used in the tap water there already is a large enough population of nitrifying bacteria in the tapwater even if chloramine is used it still aint enough to kill them all.

End conclusion, there was no significant faster growth of bacteria with the use of any of those bacterial products.. Bottom line was, you do not absolutely need them..

 

[Soilwork]

Hi all, I think these are very relevant questions, and this is discussed, to some degree in the <"Best way to cycle a second...">.

I think the answer is that nitrification is likely to occur at lower levels of dissolved oxygen than was originally thought, mainly because the <"organisms involved are Archaeae">. The work on Aquarium filters is reported in <"Aquarium Nitrification Revisited: Thaumarchaeota Are the Dominant Ammonia Oxidizers in Freshwater Aquarium Biofilters">.

The real problem is that, most of what, we thought, we knew about the ammonia oxidising organisms (AOO), isn't actually true for aquariums. Earlier work (and bacterial supplements) utilised Nitrosomonas, Nitrobacter and Nitrospira based on work originally done on sewage treatment etc. Subsequent research has shown that only Nitrospira (which was thought to convert nitrite (NO2) to nitrate (NO3)) is present, and that Nitrospira can also <"directly oxidise ammonia (NH3) to NO3">.

Doctor Hovanec's comments on changes in our knowledge about nitrifying organisms are here: <"Bacteria revealed">, and it is well worth a read. His scientific papers are <"here">, and his products page is here: <"DrTim's Aquatics">, where you can buy the latest incarnation of <"One and Only: Live Nitrifying Bacteria">, which doesn't need to be refrigerated. I'm not sure any-one will know. You can make assumptions based on the natural habitat of fish, rheophilic fish from cooler waters are likely to be the most vulnerable to low oxygen levels. There is more discussion in <"Aeration and dissolved oxygen....">

Due to the relationship between temperature and gas solubility (as temperature rises solubility falls) warm water that is 100% saturated with oxygen may not not contain enough dissolved oxygen (in mg/l) to sustain some fish. There is a chart to work out the relationship between temperature and DO in <"Twinstar..what is it: page 34">.

There are minimum figures for the organisms grown in commercial aquaculture, you could assume that Atlantic Salmon (Salmo salar) would be about the most sensitive, and it needs <70% DO levels (at 16oC) for growth, and the hypoxia tolerance threshold is 47% O2.

cheers Darrel

Thanks. I'll read all of those links later on.

What do you think is the suffering factor that separates waste water treatment facilities to aquariums that would trigger a different type of bacteria to grow?

Why are they not focussing on developing a 'archaea in a bottle' product? I read a link posted by yourself a while back regarding this and it would seem that the bacteria do exists but true predominant ammonia oxidising organism was the archeae.

Do you believe this products are genuine? Can the bacteria really survive in these bottles and are they really just a money making scam? I'm just not convinced by them at all.

Why do you think people report filter die off when canisters stop running. Can the DO levels for whatever organisms are in there fall below the threshold? I'd assume that if this happened the fish would already be in far more trouble again depending on the scenarios with regards to temp, atmospheric pressure, surface agitation etc.

 

[Soilwork]

Once did read an article at a pond community about starting up ponds with bacteria, (not in english) where sevral products were tested.. The gel products performed the best, the powder and liquid products did nearly add nothing but ammonia and nitrite and were considered a waste of money..

In areas where no chloramine is used in the tap water there already is a large enough population of nitrifying bacteria in the tapwater even if chloramine is used it still aint enough to kill them all.

End conclusion, there was no significant faster growth of bacteria with the use of any of those bacterial products.. Bottom line was, you do not absolutely need them..

Cheers for that. I don't use them and never have. I try to convince people not to waste their money. I even question the ability to culture aerobic organisms and get them to our tanks without them perishing.

 

[zozo]

I try to convince people not to waste their money

Touch job if professional advocate the benefit of using it.. Look at the James Findley videos with the use of his ADA powder collection he sprinkless around.. Honnestly states, not necessary but defenitely beneficial for the longevity of the tank. Which is a rather vague statement adressing all that to the powders.. Seeing his first videos, he used a simple paint brush to work around with his substrate and all of a sudden he later switched to that ADA stainless scoop thing, i do not see this thing beeing more sufficient than a paint brush on the contrary, but it probably is a sponsoring/marketing thing after his videos proofed to be so popular..

 

[sciencefiction]

I used the Tetra safe start product years ago which I think is the European version of Dr Tim's one and only. And the stuff worked to cycle two tanks from scratch in a week. I remember the ammonia never crossed 1ppm and the nitrite peaked for 12 hours and then dropped down to zero like a rocket. That was it, Monday to Sunday cycling done.

There were a lot of bad products out there before that were useless. Not all of them are.

I read a paper once.Unfortunately I can't quote it as I don't keep track of what I read. But they did tests on established media in aquariums and the outcome was that the bacteria restores its capability fully in 12-24hrs after being "inactive" for many days. The longer its been left without vital supplies, the longer it takes it to recover. However, it takes it a very long time to die off completely providing the media doesn't dry out.

Over the years, I've happened to accidentally leave tanks without running filters. This has happened mostly in my small tanks as I don't pay as much attention if everything is back up and running. I've never had a problem. I've done that to my shrimp only tank at least 4-5 times because my adaptor is too heavy and unplugs the filter from the wall which is behind the sofa, so I don't even notice it for days....

The only time I had a problem was when I thoroughly washed the only filter in the tank years ago. I washed and washed the media until it was perfectly clean It didn't cause a mini cycle. It caused a massive cycle...I had never seen such ammonia levels, even in newly established tanks...It stunk of ammonia and my corys fins melted overnight...hence I noticed something is wrong...

 

[Soilwork]

I used the Tetra safe start product years ago which I think is the European version of Dr Tim's one and only. And the stuff worked to cycle two tanks from scratch in a week. I remember the ammonia never crossed 1ppm and the nitrite peaked for 12 hours and then dropped down to zero like a rocket. That was it, Monday to Sunday cycling done.

There were a lot of bad products out there before that were useless. Not all of them are.

I read a paper once.Unfortunately I can't quote it as I don't keep track of what I read. But they did tests on established media in aquariums and the outcome was that the bacteria restores its capability fully in 12-24hrs after being "inactive" for many days. The longer its been left without vital supplies, the longer it takes it to recover. However, it takes it a very long time to die off completely providing the media doesn't dry out.

Over the years, I've happened to accidentally leave tanks without running filters. This has happened mostly in my small tanks as I don't pay as much attention if everything is back up and running. I've never had a problem. I've done that to my shrimp only tank at least 4-5 times because my adaptor is too heavy and unplugs the filter from the wall which is behind the sofa, so I don't even notice it for days....

The only time I had a problem was when I thoroughly washed the only filter in the tank years ago. I washed and washed the media until it was perfectly clean It didn't cause a mini cycle. It caused a massive cycle...I had never seen such ammonia levels, even in newly established tanks...It stunk of ammonia and my corys fins melted overnight...hence I noticed something is wrong...

Thank you. That is interesting. Of the BIAB that have been reported to have worked i do see this one cropping up time and again.

I can understand the bacteria restoring capability in short periods of time without a substrate such as ammonia but oxygen? I'd have though that this was of vital importance since we continually focus on the need to ensure good DO levels in any aquarium environment.

I was thinking more of an enclosed filter that has collected a lot of detritus. Without a source of fresh flow and oxygen and a heavy bioload i was wondering if they can become anaerobic to the point that destroys some of the bacteria.

 

[dw1305]

Hi all,

What do you think is the suffering factor that separates waste water treatment facilities to aquariums that would trigger a different type of bacteria to grow?

The evidence looks pretty convincing that it is the level of ammonia.

Bizarrely some of the advocates of ammonia based cycling <"are now arguing that you want the bacteria favoured by heavy ammonia levels in the cycling stage of the tank to deal with the heavy ammonia load that they are adding">. No, I don't understand it either.

There is research from the waste water industry that shows that even in (very) polluted water that the Archaea are important. <"Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant">.

Why are they not focussing on developing a 'archaea in a bottle' product? I read a link posted by yourself a while back regarding this and it would seem that the bacteria do exists but true predominant ammonia oxidising organism was the archeae.

They may well be. I'm not sure how "One and Only" is produced (and I'm pretty sure that Dr Hovanec won't tell you), it may well contain both Bacteria and Archaea.

Do you believe this products are genuine? Can the bacteria really survive in these bottles and are they really just a money making scam? I'm just not convinced by them at all.

I'd have to say sceptical, but If "One and only" (and "Tetra Safe Start") were Archaea based long term survival would become more likely.

Why do you think people report filter die off when canisters stop running. Can the DO levels for whatever organisms are in there fall below the threshold?

The problem for a lot of people is that their canister filters are running at a fraction of their biological filtration capacity, because they are always deficient in oxygen.

Once the filter stops running, ammonia levels start to rise, causing a positive feedback loop where low levels of dissolved oxygen cause fish death, which raises the level of ammonia, which lowers the level of dissolved oxygen etc.

If you don't have plants and a substrate, and fill your filter with floss etc, you have a single point of failure and will definitely have a <"disaster sooner or later">.

Without a source of fresh flow and oxygen and a heavy bioload i was wondering if they can become anaerobic to the point that destroys some of the bacteria.

Yes, they certainly can.

I used the Tetra safe start product years ago which I think is the European version of Dr Tim's one and only. And the stuff worked to cycle two tanks from scratch in a week. I remember the ammonia never crossed 1ppm and the nitrite peaked for 12 hours and then dropped down to zero like a rocket.

There are lots of people who have been successful with bacterial supplements and ammonia based cycling, it isn't a guaranteed failure, or a guaranteed success, it is somewhere in the middle.

I've never had a problem. I've done that to my shrimp only tank at least 4-5 times because my adaptor is too heavy and unplugs the filter from the wall which is behind the sofa, so I don't even notice it for days....

I've done it as well, if you have planted tanks it often doesn't matter, if you don't have plants it always matters.

cheers Darrel

 

[sciencefiction]

I've done it as well, if you have planted tanks it often doesn't matter, if you don't have plants it always matters.

Yes, planted tanks.

 

[Soilwork]

Thanks

Hi all, The evidence looks pretty convincing that it is the level of ammonia.

Bizarrely some of the advocates of ammonia based cycling <"are now arguing that you want the bacteria favoured by heavy ammonia levels in the cycling stage of the tank to deal with the heavy ammonia load that they are adding">. No, I don't understand it either.

There is research from the waste water industry that shows that even in (very) polluted water that the Archaea are important. <"Low-ammonia niche of ammonia-oxidizing archaea in rotating biological contactors of a municipal wastewater treatment plant">. They may well be. I'm not sure how "One and Only" is produced (and I'm pretty sure that Dr Hovanec won't tell you), it may well contain both Bacteria and Archaea. I'd have to say sceptical, but If "One and only" (and "Tetra Safe Start") were Archaea based long term survival would become more likely. The problem for a lot of people is that their canister filters are running at a fraction of their biological filtration capacity, because they are always deficient in oxygen.

Once the filter stops running, ammonia levels start to rise, causing a positive feedback loop where low levels of dissolved oxygen cause fish death, which raises the level of ammonia, which lowers the level of dissolved oxygen etc.

If you don't have plants and a substrate, and fill your filter with floss etc, you have a single point of failure and will definitely have a <"disaster sooner or later">.Yes, they certainly can. There are lots of people who have been successful with bacterial supplements and ammonia based cycling, it isn't a guaranteed failure, or a guaranteed success, it is somewhere in the middle. I've done it as well, if you have planted tanks it often doesn't matter, if you don't have plants it always matters.

cheers Darrel

Thanks Darrel. I did a lot of research on cycling when I first started on another forum. I posted a lot of it on there.

I found this paper by Dr. Hanovec which I have found very useful.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC124703/#!po=13.1579

It's suggest cycle lead times and an end time if between 33-38 days in lab conditions with nitrospira being the the detected NOB. I have found these times to be very very consistent with fishless cycles that I have monitored on other people's threads to the point of creating a thread to document this.

I think that people overestimate the resilience of the organisms in our tanks. Sometimes I haven made changes to my tank and all has been well yet other times i do almost the same thing and something skews off and I get cloudy water or strange fish behaviour.

Is it possible that in cases where people have had a power outage for a number of days and rebooted the canister with no problems have been backed up by organisms in the substrate and decor?

Edit: it's comment like this the give me cause for concern.

'I doubt if all your bacteria are dead. If they die within 3 days, the "bacteria in a bottle" companies are going to have some explaining to do'

Taken from
https://googleads.g.doubleclick.net/pagead/drt/si

 

[sciencefiction]

Is it possible that in cases where people have had a power outage for a number of days and rebooted the canister with no problems have been backed up by organisms in the substrate and decor?

I am pretty certain the bacteria colonises everything, the substrate, the décor and the glass. Sometimes when you move fish over from tank to tank, if you don't move the substrate and décor as well, you can cause a mini cycle.

When I was a kid I kept a river loach, that was caught for bait for fishing, in a tank with no filter, no air stone, no plants, no substrate either...for 5 years. I only changed the water in it. Dumped the old one and filled from buckets where we stored water because we had water outages. I did that once a week, no more.

Eventually my mother killed the loach by washing, his "manky" tank in her opinion, with soap and hot water. The glass was not covered in any algae I could see. But it was extremely slimy. That's what kept my loach alive. I was devastated when I came back from summer camp and she told me what had happened.
I never knew what he was but he looked a lot like a kuhli loach body shape wise and was very outgoing and playful. I never had a heater so he survived in very low temps as we didn't have central heating.

 

[dw1305]

Hi all,

Is it possible that in cases where people have had a power outage for a number of days and rebooted the canister with no problems have been backed up by organisms in the substrate and decor?

I think it probably is, but it might also depend on how recently the canister media has been cleaned.

When I've posted on other forums about why plants are so important I've always made clear that the biological filtration in planted tanks is a plant/microbe system, and that the plants create conditions where you have a greater surface area for nitrification within the substrate.

I also always mention Diana Walstad's "aerial advantage". There are plenty of papers on oxygen transport by plants to the substrate from work on constructed wetlands, this is an interesting one <"Community Structure and In Situ Activity of Nitrifying Bacteria in Phragmites Root-Associated Biofilms">.

I found this paper by Dr. Hanovec which I have found very useful. <"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC124703/#!po=13.1579"> It's suggest cycle lead times and an end time if between 33-38 days in lab conditions with nitrospira being the the detected NOB.

Yes, I think the subsequent ~20 years have shown that Nitrospira is a much more significant player in nitrification then was originally assumed, partially because they have been found to be virtually ubiquitous in the environment. As well as their role in converting NO2 to NO3, it is now known that Nitrospira bacteria have the the <"urease enzyme">, and can <"directly oxidise ammonia to nitrate">.

There are time scales for the appearance of NOB in <"Bacteria revealed">, which is a review, in light of further experimentation, of his 1998 paper.

cheers Darrel

 

[Soilwork]

Thanks Everyone. On closing this thread I have one more question.

I recently dug up my soil substrate and replaced it with eco complete. I couldn't catch all the fish because of the dense plant mass and when I took a plants out to get better access I virtually couldn't see anything. I cought about two thirds.

Thinking about this now whilst typing I don't know why I had the canister running whilst doing this. I replaced about 95% of the water but the fish had already been exposed to pretty heavily dirtied water column. The substrate was smelly and there were odd cold spots in the soil that I could feel as I was scooping it out.

After everything was done I lost a runt harlequin. It had red spots on its underbelly and near its gills. I didn't clean out them filter as quickly as I should have as I thought a 95% water change would bide me a bit more time.

The result was 4 more dead fish yesterday when I got home. The ammonia was up to about 1ppm. The canister filter was very dirty.

Do you think the canister was producing ammonia from the soil that entered?

And lastly, how often do you clean your canisters in a lightly stocked tank taking co2 injection in to account as I believe high tech tanks produce more waste. Would you expect the filter to reduce in efficiency as the time between cleaning increased?

 

[sciencefiction]

The ammonia was released from the substrate, not the canister. It's not just ammonia that gets released but all types of unwanted gases that are naturally produced by microbial activity. The damage may have been done before you did the water change though if you had 1ppm lingering ammonia afterwards, it didn't help anyone recover either...

I can't comment on CO2 injected tanks because I've got none, but I've never noticed having ammonia/nitrite issues by not cleaning the canisters regularly.
Cleaning too often or not cleaning it enough are both harmful. I put pre-filter sponges on the intakes and that keeps the big bits away for a good while. That's especially important in a planted tank or tanks with strong filtration where soil, debris and food can get sucked in the filters daily. You want just clean enough water getting into the filter. If you mess up a lot with the tank's substrate, you need to clean way more often and you probably need more filtration too to compensate for the ammonia spikes created by that. I have some blue sponges in my filters. They're still blue and not clogged months after not cleaning. If I had no prefilters, they'd be full of gunk.

Folks that keep CO2 planted tanks often suffer from the "consistent diatom" problem because of messing up with the substrate often. They blame it then on too much light and not enough co2. Its the regular mini ammonia spikes and consistent high levels of organics that trigger algae and kill fish early or later.

 

[dw1305]

Hi all,

Do you think the canister was producing ammonia from the soil that entered?

The ammonia was released from the substrate, not the canister.

I agree with "sciencefiction", the disturbed substrate is the most likely source. The problem with the debris in the filter is that itis likely to have slowed the water flow, and clogged the filter media, leading to low levels of dissolved oxygen.

I can't comment on CO2 injected tanks because I've got none...

Same applies I've never added CO2.

but I've never noticed having ammonia/nitrite issues by not cleaning the canisters regularly. Cleaning too often or not cleaning it enough are both harmful. I put pre-filter sponges on the intakes and that keeps the big bits away for a good while. That's especially important in a planted tank or tanks with strong filtration where soil, debris and food can get sucked in the filters daily. You want just clean enough water getting into the filter. If you mess up a lot with the tank's substrate, you need to clean way more often and you probably need more filtration too to compensate for the ammonia spikes created by that. I have some blue sponges in my filters. They're still blue and not clogged months after not cleaning. If I had no prefilters, they'd be full of gunk.

That is the approach I take, I have a pre-filter that I clean ~weekly, but the canister itself I only usually open every ~6 months or so. I have Asellus and Snails in the filter, and there is usually very little biofilm on the canister media.

Snails in trickle filters for waste water treatment can be a major problem, because the snails are very effective at consuming the biofilm and limiting the rate of nitrification of ammona. This is from "Application of high rate nitrifying trickling filters to remove low concentrations of ammonia from reclaimed municipal wastewater."

Results showed that nitrification was impeded by a combination of high organic carbon loads and aquatic snails, which consumed much of the active biomass.

My suspicion would be that the majority of filtration problems are caused by people not having a pre-filter and either by design, or accident, using their filter as a syphon.

cheers Darrel

 

[Soilwork]

The ammonia was released from the substrate, not the canister. It's not just ammonia that gets released but all types of unwanted gases that are naturally produced by microbial activity. The damage may have been done before you did the water change though if you had 1ppm lingering ammonia afterwards, it didn't help anyone recover either...

I can't comment on CO2 injected tanks because I've got none, but I've never noticed having ammonia/nitrite issues by not cleaning the canisters regularly.
Cleaning too often or not cleaning it enough are both harmful. I put pre-filter sponges on the intakes and that keeps the big bits away for a good while. That's especially important in a planted tank or tanks with strong filtration where soil, debris and food can get sucked in the filters daily. You want just clean enough water getting into the filter. If you mess up a lot with the tank's substrate, you need to clean way more often and you probably need more filtration too to compensate for the ammonia spikes created by that. I have some blue sponges in my filters. They're still blue and not clogged months after not cleaning. If I had no prefilters, they'd be full of gunk.

Folks that keep CO2 planted tanks often suffer from the "consistent diatom" problem because of messing up with the substrate often. They blame it then on too much light and not enough co2. Its the regular mini ammonia spikes and consistent high levels of organics that trigger algae and kill fish early or later.

I think I underestimated how much ammonia would be released. The substrate had been down for over 6 months.

On the contrary, I have had my greatest success when with livestock longevity whilst injecting co2 and keeping a substantial plant mass. Granted I have perhaps not approached the non co2 methods in the correct way. I definitely believe that both systems are very robust when in balance but thinks will spiral out of control faster with high light and co2. Or if someone attempts to deforest the tank incorrectly

 

[Soilwork]

Hi all,I agree with "sciencefiction", the disturbed substrate is the most likely source. The problem with the debris in the filter is that itis likely to have slowed the water flow, and clogged the filter media, leading to low levels of dissolved oxygen.Same applies I've never added CO2. That is the approach I take, I have a pre-filter that I clean ~weekly, but the canister itself I only usually open every ~6 months or so. I have Asellus and Snails in the filter, and there is usually very little biofilm on the canister media.

Snails in trickle filters for waste water treatment can be a major problem, because the snails are very effective at consuming the biofilm and limiting the rate of nitrification of ammona. This is from "Application of high rate nitrifying trickling filters to remove low concentrations of ammonia from reclaimed municipal wastewater." My suspicion would be that the majority of filtration problems are caused by people not having a pre-filter and either by design, or accident, using their filter as a syphon.

cheers Darrel

6 months seems like a long while. I wish I could leave mine that long but it makes sense to clean the filter at the same time as the inline atomiser which dirties more quickly.

Even though the results are not apparent, do you think the filter has declined in efficiency at say month 5 as opposed to month 2?

Edit: does the same water ever haze or cloud after cleaning?

 

[roadmaster]

Filter's could become less efficient at 5 month's or five week's, depending on what they are filtering (ie) Organic input.

 

[dw1305]

Hi all,

6 months seems like a long while.

Filter's could become less efficient at 5 month's or five week's, depending on what they are filtering (ie) Organic input.

Yes, I agree with "roadmaster" It could be, but I have substantial pre-filter sponges, which I clean regularly.

A lot of the initial criticism of the first draft of <"aeration and dissolved oxygen.."> centred around the likelihood of air locks happening caused by the filter intake taking in air bubbles. Until that point it hadn't occurred to me that people would use the scaffold type filter intakes without a sponge pre-filter, I'd just assumed that everybody would use a pre-filter to stop bits of plant, food, faeces etc ending up in the filter.

When I asked why people didn't use pre-filter sponges I was told that they stopped faeces, bits of plants etc getting into the filter, and that was actually what the filter was for, "why else would it be called a filter?"

Another advantage of pre-filter sponges is that you can aim a filter venturi at them, and a large number of air bubbles will be trapped in the sponge surface, allowing oxygen to diffuse into the water flow into the filter.

People were worried that biological filtration would occur in the pre-filter, and this was also a worry about plants, if they really were so effective, that they would limit biological filtration in the filter media. A lot of these worries were because people had been told that the filter bacteria would die without ammonia, that too much oxygen in the filter was a bad thing (because it limited anaerobic denitrification) and that plants used oxygen and contributed to the bioload.

All these statements have a grain of truth in them, but in combination they can lead to some horrible things happening.

Even though the results are not apparent, do you think the filter has declined in efficiency at say month 5 as opposed to month 2?

The flow rate will have dropped off, but I think that has much more to do with algal growth in the hoses, rather than the development of biofilm in the filter. I've never had much biofilm on any of the filter media, and I would suspect that even after several years that wouldn't have changed a huge amount.

Edit: does the same water ever haze or cloud after cleaning?

No, it doesn't, and I would be concerned if it did.

cheers Darrel