# Bio-filtration Required?



## dwalstad (Apr 14, 2006)

Here's a good question sent to me today.

Question: I read your article on nitrogen uptake in aquatic plants. (_Note: article is available on my website._) Given that (most) aquatic plants are adept at processing ammonium (ammonia?) and nitrites. Can I conclude that we can over-filter our water with biological filtration? In other words, are we filtering out the very chemicals that plants need? Thank you again.

Answer: Yes. Filtration removes ammonia that plants prefer and replaces them with nitrates, which require more energy for plants to fulfill their nitrogen needs. Moreover, filtration sometimes includes lots of aeration/bubbling which degasses off precious CO2.

Ammonia is taken up by plants more easily than ammonium; in fact, ammonia diffuses freely into the plant. Ammonia (NH3) has no electrical charge, so it easily crosses the lipid membrane barrier of plant cells. Ammonium (NH4+), in contrast, has a positive charge so cells can regulate its uptake-which is a good thing--but that requires some processing. I would conclude from this that ammonia is probably taken up _slightly_ more easily than ammonium by plants.

There's a Golden Rule here: the uncharged nature of ammonia is part of the reason why it is toxic to plants and fish when it is in excess. Their cells simply cannot regulate its uptake. It diffuses unregulated through the lipid membrane barrier and creates havoc within the cell. The same rule applies to H2S; because it has no charge, cells cannot keep it out.

Moderate water circulation can be useful. It brings nutrients to plant leaves more quickly. It also distributes heat, especially beneficial to large, deep tanks. Organic soil substrates like potting soil are oxygen-hungry first 8 weeks, sometimes making life difficult for plant roots. Circulation of the overlying water helps aerate those soil substrates.

If you have a small tank (1-10 gal) with good submerged plant growth and a moderate fish load, you don't filtration. With a larger tank newly set up with soil and with lots of fish, you might need some filtration to help oxygenate water as well as to remove ammonia.


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## FromReefs2Plants (Aug 14, 2017)

I use an aqualcear 50 on my 55g NPT with great success. I think some water movement is vital, I just added a powerhead. THe fish love it, we shall see about the plants.


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## Michael (Jul 20, 2010)

I use Aquaclear filters on most of my tanks, but only with mechanical media--the sponge that comes with the filters. Some biological filtration does occur in the sponge. I'm careful to keep the water level high enough in the tanks so that the output from the filter flows smoothly with no splashing or free fall into the tank.


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## terryna (Mar 16, 2018)

I shall be following this


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## EvanC (Mar 10, 2020)

Michael said:


> I use Aquaclear filters on most of my tanks, but only with mechanical media--the sponge that comes with the filters. Some biological filtration does occur in the sponge. I'm careful to keep the water level high enough in the tanks so that the output from the filter flows smoothly with no splashing or free fall into the tank.


I'm going to set up a 17 gallon soon. Would this qualify as a tank benefiting from a HOB for circulation? Also, do you pull out the carbon filter that comes with an aquaclear and just leave the foam?


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## hoppycalif (Apr 7, 2005)

Filter carbon is only effective for a short time. It soon gets loaded with large molecules and, from then on, it only acts as a biofilter - a place for bacteria to establish colonies. If you remove it before using it, you can save it for the possibility of later wanting to remove medicines or organic dyes from the water.


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## Chris829 (Mar 24, 2020)

I had a silly question but I'm currently adding more fish to my 4 week old 75 gallon planted aquarium. If ammonia is the first thing used by the plants for energy then why have a moderate fish load? Wouldn't more fish make more ammonia? I have 5 nickle sized angelfish, six panda corydora, 1 betta, and I just bought 8 red neon blue eyed rainbow online. I eventually want to add 14 or 15 cardinal tetras and some German Blue rams would that be considered a moderate fish load for a 75 gallon or is that excessive? Thank you for the input in advance.


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## Michael (Jul 20, 2010)

EvanC said:


> I'm going to set up a 17 gallon soon. Would this qualify as a tank benefiting from a HOB for circulation? Also, do you pull out the carbon filter that comes with an aquaclear and just leave the foam?


Yes, don't install the carbon packet. And you don't need the bag of ceramic biomedia that comes with the filter either.


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## Michael (Jul 20, 2010)

Chris829 said:


> I had a silly question but I'm currently adding more fish to my 4 week old 75 gallon planted aquarium. If ammonia is the first thing used by the plants for energy then why have a moderate fish load? Wouldn't more fish make more ammonia? I have 5 nickle sized angelfish, six panda corydora, 1 betta, and I just bought 8 red neon blue eyed rainbow online. I eventually want to add 14 or 15 cardinal tetras and some German Blue rams would that be considered a moderate fish load for a 75 gallon or is that excessive? Thank you for the input in advance.


Plants don't use ammonia for energy, they use it for a nitrogen source. And too much ammonia is toxic to both plants and fish.

As far as your fish list goes, my main concern is that those angelfish will not stay nickle size for long!


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## Chris829 (Mar 24, 2020)

Ok so moderate amount of ammonia good too much is bad...got it 😉

As far as the angelfish go I understand they will grow hand sized in some cases and was planning on them being the stars of the show. I was just trying to determine the moderate fish load thing. Moderate is a subjective thing I suppose. With that being said as my tank sits: 1 betta, 5 angels, 6 coryforas, 8 pseudomugil luminatus. In you guys opinion is there any room for a future school of 12 to 15 Cardinal tetras, 10 nerite snails, and a couple of rams or will this be too much for my heavily planted dirted tank?


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## adalah (Feb 10, 2019)

fromreefs2plants said:


> i use an aqualcear 50 on my 55g npt with great success. I think some water movement is vital, i just added a powerhead. The fish love it, we shall see about the plants.


+1


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## Michael (Jul 20, 2010)

You may not have too many fish, but the combination may not work. Full grown angelfish will eat cardinal tetras, and will probably terrify the blue eyes and rams so much that you will never see them.


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## zolteeC (Dec 26, 2017)

I have had also success with smaller no filter and no water circulation tanks.
I am less worried about NH4 or NH3 in my situation, plants and soil work very well for me.
What I am sometimes a bit unsure how much is the risk for low oxygen levels without water circulation. I think I have seen issues if there is alot of duckweed growing on the surface. I would not call my tanks heavily stocked by any means. In my case water temperature is also lower, around 21C stable even in the summer.

What is the recommendation on filter and water circulation with *shrimp* or snail *only* tanks?

I am experiencing with HC Cuba monoculture and RCS shrimp in a 35 liter NPT with no filter nor water circulation and things have worked fine since day 1 (6 months ago).


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## mysiak (Jan 17, 2018)

zolteeC said:


> I have had also success with smaller no filter and no water circulation tanks.
> I am less worried about NH4 or NH3 in my situation, plants and soil work very well for me.
> What I am sometimes a bit unsure how much is the risk for low oxygen levels without water circulation. I think I have seen issues if there is alot of duckweed growing on the surface. I would not call my tanks heavily stocked by any means. In my case water temperature is also lower, around 21C stable even in the summer.
> 
> ...


There is going to be an article about oxygen levels in primarily no-tech tanks released in an online Czech magazine in the coming weeks, I will ask the author if I could share his measurements here sooner (including some "standard" and high tech tanks). Results are quite interesting (I have access to the preliminary version with raw data/notes). In the "worst" case I'll translate the final version of the article once it's made public.


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## zolteeC (Dec 26, 2017)

mysiak said:


> There is going to be an article about oxygen levels in primarily no-tech tanks released in an online Czech magazine in the coming weeks, I will ask the author if I could share his measurements here sooner (including some "standard" and high tech tanks). Results are quite interesting (I have access to the preliminary version with raw data/notes). In the "worst" case I'll translate the final version of the article once it's made public.


This is great. I'd love to see some results with established NPTs, so not regular low tech tanks without soil substrate. That's a different setup.
I am usually not that worried about oxygen levels without circulation in my smaller NPTs as long as there is not too much duckweed on the surface, amount of fish is reasonable and water temperature is not too high (say around 20-24C).
However, it would be nice to see where are the "limits", how much room for error is left to stay on the safe side without water circulation.

In fish stores with very crowded tanks, if the filter stops (often its a sponge filter with air bubbles) fish may gasp for air in 15-25 mins...


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## Michael (Jul 20, 2010)

The only time I've had oxygen level problems in my Walstad tanks is during power failures. With both circulation AND lighting shut off, fish in my somewhat crowded tank show distress in about 48 hours.


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## mysiak (Jan 17, 2018)

zolteeC said:


> This is great. I'd love to see some results with established NPTs, so not regular low tech tanks without soil substrate. That's a different setup.
> I am usually not that worried about oxygen levels without circulation in my smaller NPTs as long as there is not too much duckweed on the surface, amount of fish is reasonable and water temperature is not too high (say around 20-24C).
> However, it would be nice to see where are the "limits", how much room for error is left to stay on the safe side without water circulation.
> 
> In fish stores with very crowded tanks, if the filter stops (often its a sponge filter with air bubbles) fish may gasp for air in 15-25 mins...


Unfortunatelly I can't say anything in details now (author asked me to wait), but..this is my summary which might help a little.

Generally speaking (and this is nothing new), tanks with no circulation tend to have very big variation of DO levels between night and day, tanks with filters (especial air driven sponge ones) usually have quite stable parameters.

It's impossible to tell oxygen levels by just looking at the tank, only very high oversaturation is visible (pearling). Hypoxia has different impact on livestock - some fish are able to live and breed for years even when DO is less than 2mg/l during night. Per several studies, long term or regular hypoxia has detrimental effect on fish (deformities, sickness, stunted growth etc.), but it depends on the species and their natural habitat and physiology.

If you're worried about DO levels, you can basically do two things:
1. increase amount of plants, increase the lightning period (14-15 hours) or increase the light intensity
2. add an air driven filter/air stone (mainly during night when no photosynthesis occurs)

More to come at the end of April..


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## aquabillpers (Apr 13, 2006)

Michael said:


> You may not have too many fish, but the combination may not work. Full grown angelfish will eat cardinal tetras, and will probably terrify the blue eyes and rams so much that you will never see them.


Yes! And if the angels breed, there will be even more stress on everybody!

Bill


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## dwalstad (Apr 14, 2006)

zolteeC said:


> I am experiencing with HC Cuba monoculture and RCS shrimp in a 35 liter NPT with no filter nor water circulation and things have worked fine since day 1 (6 months ago).
> 
> View attachment 63153


Nice tank! AND it shows that one can grow HC Cuba in an NPT when this species doesn't have to compete with other species.

Good to remove excess duckweed, as it will block oxygen diffusion from the water surface.

BTW, I've found that an ordinary kitchen fork works great for removing excess duckweed.


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## tiger15 (Apr 9, 2017)

I am hanging couple shrimp bowls by the window with heavy floating and carpet plants and zero tech, meaning no circulation, filter or heater. At first I worried about floating plants blocking air exchange so I placed an air tube ring to keep a breathing hole open. I later removed the ring and didn't see any difference. I have no measurement of O2 but observed pearling during 4 to 6 hour sunlight period and bright shade for the balance of day. I measured huge fluctuation of pH though, from 7.2 before to 8.5 during sunlight period, and huge diurnal temp change of as much as 20 F. My shrimp and snails are thriving and never show stress, so they must be adequately oxygenated and not bothered by huge temp and pH fluctuations. Inverts have low bio demand and since I have no fish, I don't know how fish will fair under the same set up.


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## tiger15 (Apr 9, 2017)

I run two high tech planted cichlid tanks. My filters are all Penguin HOBs for mechanical polishing only as I have never installed the biowheels nor inserted any bio media in my HOBs. I never believe there is a need for dedicated bio media or bio filters as long as there is good circulation of oxygenated water over substrate and surfaces where BB adhere to, with or without plants. Vendors will be glad to up-sell you biomedia and bio filter when all you need is to provide the right conditions for BB to thrive. All aerobic surfaces in your tank (glass, substrate, rock, drift wood and plants) are in-situ bio media so why waste money and effort to set up bio filters. With plants, your need for dedicated biofiltration is even less as plants and BB both consume NH3 directly. 

Since I have heavy bioload, my 75g is filtered with 2 Penquin 350, and my 125g with 3 Penquin 350 plus a wave maker in each to assist in circulation. This is in different from the zero tech shrimp bowls I posted above which I haven’t found the need for any circulation or filtration due to de minimus bio load.


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## Michael (Jul 20, 2010)

Wonderful to see planted cichlid tanks instead of the sterile moonscapes that are typical.


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## FromReefs2Plants (Aug 14, 2017)

I run the sponge and carbon in my aquaclear. I change the carbon monthly.Water is clear and fish look healthy.


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## Doc7 (Feb 27, 2017)

Michael said:


> The only time I've had oxygen level problems in my Walstad tanks is during power failures. With both circulation AND lighting shut off, fish in my somewhat crowded tank show distress in about 48 hours.


When Hurricane Sandy knocked out my power for 11 days and basically destroyed the area I lived in, (house got down to the 40s/50s in temps) my fish in my heavily planted tank were wiped out in a day. My fish in my totally Un planted 20 gal high tank all survived even with the 25 degree drop from normal conditions that lasted over a week. That broke my heart from the hobby for several years. Battery powered pumps were unavailable during the event and I hadn't planned properly.


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## mysiak (Jan 17, 2018)

mysiak said:


> There is going to be an article about oxygen levels in primarily no-tech tanks released in an online Czech magazine in the coming weeks, I will ask the author if I could share his measurements here sooner (including some "standard" and high tech tanks). Results are quite interesting (I have access to the preliminary version with raw data/notes). In the "worst" case I'll translate the final version of the article once it's made public.


Article can be found here http://e-akvarium.cz/casopis/akvarium48.pdf, but it's in Czech only (pages 28-49). I will try to summarize the most interesting parts (with some additional comments):

1. no-tech tanks, with soil substrate and plenty of plants (vallisneria, cryptocoryne,..) and low light have a very high difference between day and night, ranging from about 2mg/l to 8mg/l.
2. no-tech tanks, with soil substrate and plenty of plants and medium light have a very high difference between day and night, but! ranging from about 6mg/l to 12mg/l (hyperoxia at ~140% saturation).
3. no-tech tanks, with soil substrate and medium/plenty of plants and natural light are extremely depending on the day of the year (lenght of the day) and weather (sunny vs. cloudy) - 1mg/l to 18mg/l (!)
4. low-tech tanks, with soil substrate and plenty of plants and low light and with a filter - just a pure water circulation increases amount of DO by about 2-3mg/l
5. low-tech tanks with air driven sponge filters - they are at about 100% saturation, the amount of plants, light intensity or substrate seems to be insignificant

Author's conclusion (Jirka Scobak - @Jirka from Bratislava) is that "no tech" tanks can easily beat "low tech" tanks in the amount of dissolved oxygen. While I fully agree with this, at the same time we can't omit the fact, that they can be running extremely low on DO and without a very expensive DO meter we can't be really sure how good our tanks run. It's up to us to decide if we prefer a "safe bet" with stable, but a bit lower DO levels (water circulation/filter), or take a leap of faith and keep it "no tech".

Some of the repeated measurements allowed me to create this chart, showing minimum, maximum and average DO. They were NOT taken during one day, some of measurements are weeks apart, but they show how variable "no tech" tanks can be.










Edit: additional information can be found in this table. In comments you can find what kind of impact on DO have various actions (addition of light, change of the bulb etc.)
https://docs.google.com/spreadsheets/d/1VABiQEzIH3BcmUUlPNMi9BdKwMy_eTw-lKHLxNDxq48/edit?usp=sharing


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## mysiak (Jan 17, 2018)

I don't want this table to get lost in the text above, so pasting it here separately:

https://docs.google.com/spreadsheets/d/1VABiQEzIH3BcmUUlPNMi9BdKwMy_eTw-lKHLxNDxq48/edit?usp=sharing


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## mistergreen (Mar 3, 2007)

Do you know what's the optimal DO saturation for fish?


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## mysiak (Jan 17, 2018)

mistergreen said:


> Do you know what's the optimal DO saturation for fish?


There is no single and easy answer. When I was doing research of existing studies, I stumbled upon many interesting articles. Some fish require at least ~90% saturation (mostly cold water species living in streams), others are able to live and breed even with 20% saturation (tropical species from Amazon). It mostly depends on natural habitat of fish - if they live in waters with very variable DO content, they have several biological and behavioral mechanisms to help them to cope with this situation. However in most studies it was mentioned that lower than optimal DO levels should be avoided. Long term hypoxia can result in sick fish, stunted growth, no/low breeding, birth deformities etc. Interestingly, high levels of DO (~150% saturation and higher) can have detrimental effects on fish as well. But again it depends on species, some cope with oversaturation better than others.

In the article above it's mentioned that Jirka successfully breeds stable colonies of livebearers (Girardinus falcatus and Heterandria formosa) in tanks which had the lowest extremes of 1ppm and 2ppm of DO. Fish don't show any visual impact of these less than optimal conditions. Maybe they don't reach their full growth/lifespan potential, but that is hard to confirm in home conditions.


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## FlatfishTanker1 (Mar 13, 2020)

Here is a picture of my custom filter system I built for my 40G tank. It's a pretty simple sponge filter with a large area of medium poret sponge purchased from Swiss Tropicals (The makers of Matten filters). The filter will be driven by a water pump by day. You can see that the output spouts are well below the water surface so as not to disturb the surface too much. Surface agitation releases CO2 that plants need/use when the lights are on during the day. We want the CO2 to stay in the water so the plants can use it and in turn, produce oxygen. So no need to add oxygen during the day. Then, At night, when the lights are off and the plants are no longer producing oxygen, my filter will switch over to the air lifter to circulate the water and add oxygen to the water. Simple timers will turn each on and off as needed. Again, I refer to Diana Walstads book for my education on these issues. I hope I understand this correctly. Water pump by day, air driven by night. As per the original question of this thread (it was me) I understand that as my tank becomes well established, I may not need so much filtration and will dial it back considerably as needed.


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