# Why filter?



## Soilwork

A question for those that don’t want to fertilise their plants.  Why use a filter?

I can understand the reason behind encouraging massive microbial nitrification in a water treatment facility but in a planted tank that doesn’t use fertiliser you filter is removing ammonia and microscopic particulate food for your critters.  Let the plants do the work and feed heavily.  I don’t agree with all of Diana Walstads principals but she was right when she said ‘you’re not feeding the fish, you’re feeding the plants’

If you allow the mulm to build up in the substrate gives a better medium for your plants to grow in over time and doesn’t encouraging high turnover increase oxygen demand?  I know this can easily be overcome but I prefer slower flow, no mechanical filtration and overfeeding.  There is definitely a better response in these kind of natural aquariums in my experience.

Cheers CJ


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## Edvet

There are a few examples of low tech tanks, amply planted, laden with critters and a few fish, that work very well.
First one i read about: https://www.tuncalik.com/2009/09/biotope-in-my-study/
Wellknown here on Ukaps:https://www.ukaps.org/forum/threads/toms-bucket-o-mud-the-end.14521/

You might need a way to break up surface scum which would hinder gas/surface interaction


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## dw1305

Hi all, 





Soilwork said:


> If you allow the mulm to build up in the substrate gives a better medium for your plants to grow in over time and doesn’t encouraging high turnover increase oxygen demand? I know this can easily be overcome but I prefer slower flow, no mechanical filtration and overfeeding. There is definitely a better response in these kind of natural aquariums in my experience.


You probably don't need the microbial filtration offered by the filter. "Filtration using plants" is always really filtration using "plants and microbes", and I think you will end up with a similar amount of microbial filtration when you have plants, whether they are in the filter or in the rhizosphere. 

I have had this conversation with @Bart Hazes somewhere (I can't find exactly it on <"UKAPS">, but it might have been a PM, or it may be on Apistogramma forums or his blog etc).





Soilwork said:


> ......your filter is removing ammonia and microscopic particulate food for your critters..........and doesn’t encouraging high turnover increase oxygen demand?


It may increase oxygen demand, but I'd look at the question from the other direction. 

My worry for the livestock would always be sub-optimal oxygen levels. If you have a heavy planting you may end up with low oxygen/high CO2 levels towards the end of the night. 

You can circumvent this by increasing the gas exchange surface area (adding flow) and/or by reducing the bioload. If you have a filter, with aerobic filter media, that gives you both flow and extra nitrification capacity, and that can never be a bad thing.

cheers Darrel.


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## Kalum

For me the decider is if you come at it from the fish keeper or plant keeper mindset

As as fish keeper the question would be 'why wouldn't you use a filter', giving them the best environment possible should be priority and even fish that are traditionally from mud pools and the like still deserve the best conditions we can give them in the glass boxes we put them in, it's like saying someone brought up in the smog of London wouldn't benefit from cleaner countryside air

Plant keeper side of things, why not


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## Soilwork

Edvet said:


> There are a few examples of low tech tanks, amply planted, laden with critters and a few fish, that work very well.
> First one i read about: https://www.tuncalik.com/2009/09/biotope-in-my-study/
> Wellknown here on Ukaps:https://www.ukaps.org/forum/threads/toms-bucket-o-mud-the-end.14521/
> 
> You might need a way to break up surface scum which would hinder gas/surface interaction



Thanks 

The scum could become a problem considering I don’t water change but I’ve heard bladder snails are great for surfing this?


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## Soilwork

dw1305 said:


> Hi all, You probably don't need the microbial filtration offered by the filter. "Filtration using plants" is always really filtration using "plants and microbes", and I think you will end up with a similar amount of microbial filtration when you have plants, whether they are in the filter or in the rhizosphere.
> 
> I have had this conversation with @Bart Hazes somewhere (I can't find exactly it on <"UKAPS">, but it might have been a PM, or it may be on Apistogramma forums or his blog etc).It may increase oxygen demand, but I'd look at the question from the other direction.
> 
> My worry for the livestock would always be sub-optimal oxygen levels. If you have a heavy planting you may end up with low oxygen/high CO2 levels towards the end of the night.
> 
> You can circumvent this by increasing the gas exchange surface area (adding flow) and/or by reducing the bioload. If you have a filter, with aerobic filter media, that gives you both flow and extra nitrification capacity, and that can never be a bad thing.
> 
> cheers Darrel.



Hi Darrel,

My thoughts are that even though you have microbes the lower turnover and lack of mechanical sponge benefits the plants by allowing ammonia uptake.  Their increased growth enables higher oxygen levels in the water.  The demand for oxygen simply isn’t as high in this system.  Food doesn’t get drawn in to the filter to rot away consuming oxygen.  Whats left on the bottom is quickly eaten.

I understand what you’re saying but I don’t think the low oxygen at night would be an issue in this kind of tank.


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## Soilwork

Here is an example of such a tank only this one doesn’t have a pump
. 
No pump, no filter, no heater, no fertiliser, no water changes, just sand, lighting and fish food.


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## Soilwork

Kalum said:


> For me the decider is if you come at it from the fish keeper or plant keeper mindset
> 
> As as fish keeper the question would be 'why wouldn't you use a filter', giving them the best environment possible should be priority and even fish that are traditionally from mud pools and the like still deserve the best conditions we can give them in the glass boxes we put them in, it's like saying someone brought up in the smog of London wouldn't benefit from cleaner countryside air
> 
> Plant keeper side of things, why not



My fish do better in this system than any other i have tried.


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## Edvet

Are there a buttload of Daphnia i see?


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## Soilwork

Edvet said:


> Are there a buttload of Daphnia i see?



Yes despite there being two sparking gourami in there somewhere.


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## dw1305

Hi all,
Right at the start of this reply, I'd like to say to @sciencefiction, you are right, it is the plants that make the difference, not the filter.





Kalum said:


> .......giving them the best environment possible should be priority and even fish that are traditionally from mud pools and the like still deserve the best conditions we can give them in the glass boxes we put them in, it's like saying someone brought up in the smog of London wouldn't benefit from cleaner countryside air


Same for me.





Soilwork said:


> My thoughts are that even though you have microbes the lower turnover and lack of mechanical sponge benefits the plants by allowing ammonia uptake.


The plants will still uptake the ammonia, but I think my main point would be that you will have a similar amount of microbes, whether you have a filter or not.

Even if microbial numbers are of the same order of magnitude, you are likely to have a more diverse microbial assemblage in a planted tank, because the plants will create a greater variety of niches, mainly via the oxygen and carbohydrates leaking into the rhizosphere.

<"Maximal biodiversity usually occurs in patchy environments">, where you have low nutrients and zones of fluctuating resources (oxygen, nutrients etc.), and that seems also to apply to <"nitrification in aquariums">. 





Soilwork said:


> Their increased growth enables higher oxygen levels in the water.


I'm not sure, I think that all reasonably heavily planted tanks will be pretty near oxygen saturation point at the end of the photo-period. You can even get pearling (via the Cyanobacteria) at sewage treatment works if the sun is out. Have a look at <"A question.....">. 





Soilwork said:


> Food doesn’t get drawn in to the filter to rot away consuming oxygen.


I think we probably all agree on that. I've always been an advocate of not using your <"filter as a syphon">.





Soilwork said:


> I understand what you’re saying but I don’t think the low oxygen at night would be an issue in this kind of tank.


That is the great unknown, <"it is going to depend on all sorts of factors">.

I actually look on dissolved oxygen as different from all other parameters, because it only needs a very short period of time where it is sub-optimal  to kill all your fish. Everything else you get a bit of warning, or wriggle room, but with dissolved oxygen you don't.

My argument for keeping a large gas exchange surface is <"really "risk management"> or "belt and braces" one. You may not run much risk of having low dissolved oxygen levels, but if it does occur the consequences are as severe as possible, and having a filter removes a single point of failure. 





Soilwork said:


> My fish do better in this system than any other i have tried





Edvet said:


> Are there a buttload of Daphnia i see?





Soilwork said:


> Yes despite there being two sparking gourami in there somewhere.


<"Anabantoid fish"> are the safest option in a tank without flow, because they have the ability to extract oxygen directly from the air via their labyrinth organ.

I've found that _Daphnia_ do better in a tank with no flow as well.

cheers Darrel


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## Joel S

I recently set up a 60cm tank having had success with a very small filterless tank. On the 60cm I had a lot of initial melting that did not happen to the same extent with the smaller tank (there are other major variables like harder tap-water and different substrate and more slow-growers) but I was amazed to see the plants (and lethargic Otos and shrimp) perk up the moment I added a small amount of flow from a little internal filter.

I’m still interested to go filterless on this tank perhaps when the plants are more established, but new leaves only started to appear after I added this small amount of flow (of course it could just be down to the general settling of the tank, but the improvement was so fast...)


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## roadmaster

Dissolved Oxygen levels at night would be easy to measure with DO meter with/without flow from pumps or filters no?
I place much higher value on livestock than weeds ,and though plants might not be affected too adversely from no filtration or movement of water,I could maybe not be so confident regarding livestock.
Some species more needy that others with respect to O2 and comfort levels,


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## dw1305

Hi all,





roadmaster said:


> Dissolved Oxygen levels at night would be easy to measure with DO meter with/without flow from pumps or filters no?
> I place much higher value on livestock than weeds ,and though plants might not be affected too adversely from no filtration or movement of water,I could maybe not be so confident regarding livestock.....


Yes, it would be easy enough with a DO meter, unfortunately they are expensive bits of kit. We actually have some in the lab (for water testing in the field), but I still haven't actually left one logging in an aquarium.

We do have a thread that looks at this, but <"using pH as a proxy"> for oxygen/CO2 content.  This is the thread <"Maxing CO2 in ....">. 





roadmaster said:


> Some species more needy that others with respect to O2 and comfort levels,


They definitely are, a fish from <"cooler, rapidly flowing water"> may be discomforted at oxygen levels that are absolutely fine for most fish.

cheers Darrel


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## Soilwork

roadmaster said:


> Dissolved Oxygen levels at night would be easy to measure with DO meter with/without flow from pumps or filters no?
> I place much higher value on livestock than weeds ,and though plants might not be affected too adversely from no filtration or movement of water,I could maybe not be so confident regarding livestock.
> Some species more needy that others with respect to O2 and comfort levels,



I also place high value on my stock than weeds.  This thread is supposed to discuss the relationship between all aspects of the tank and how they affect one another.  I could easily argue that I care for my livestock so much so that I removed my co2 injection and stopped doing large weekly water changes or dosing fertiliser.  But as we know, that would stir up another discussion.  We all look at things differently.

This no flow tank has shrimp and Daphnia as well as the anabantoids.  If we use the daphnia, canary and coal mine analogy as has been used once or twice before for determining water quality.  BOD should also be included in this.  The thriving daphnia should offer an interesting insight here.


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## roadmaster

Soilwork said:


> I also place high value on my stock than weeds.  This thread is supposed to discuss the relationship between all aspects of the tank and how they affect one another.  I could easily argue that I care for my livestock so much so that I removed my co2 injection and stopped doing large weekly water changes or dosing fertiliser.  But as we know, that would stir up another discussion.  We all look at things differently.
> 
> This no flow tank has shrimp and Daphnia as well as the anabantoids.  If we use the daphnia, canary and coal mine analogy as has been used once or twice before for determining water quality.  BOD should also be included in this.  The thriving daphnia should offer an interesting insight here.



My apologies. Threads title "Why Filter"was all I saw. My observations with respect to O2 levels that may or may not be what we might think was but one aspect rather than what you intended.
Believe there is always more O2 in moving water than stagnant water and have seen no detriment to weeds or fishes/inverts from such water movement so I feel it is win/win.


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## Kalum

Soilwork said:


> I also place high value on my stock than weeds.  This thread is supposed to discuss the relationship between all aspects of the tank and how they affect one another.  I could easily argue that I care for my livestock so much so that I removed my co2 injection and stopped doing large weekly water changes or dosing fertiliser.  But as we know, that would stir up another discussion.  We all look at things differently.
> 
> This no flow tank has shrimp and Daphnia as well as the anabantoids.  If we use the daphnia, canary and coal mine analogy as has been used once or twice before for determining water quality.  BOD should also be included in this.  The thriving daphnia should offer an interesting insight here.



I don't think you can ask the question of why filter without it being a discussion like it has been and like you say taking all aspects into account

You definitely have a point with co2 and to an extent ferts, but both of these are easily measurable by us that allow it to be kept within parameters to not adversely affect the livestock

I think if everyone took the no filter and no water change approach there would be carnage as not many would be able to execute it and keep it a good environment for livestock and plants alike 

It's just something different and nobody is saying it can't be done, far from it, but a filter and water changes allow a safety net for me to ensure I'm doing what I can and one that I wouldn't be comfortable without


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## Soilwork

Kalum said:


> I don't think you can ask the question of why filter without it being a discussion like it has been and like you say taking all aspects into account
> 
> You definitely have a point with co2 and to an extent ferts, but both of these are easily measurable by us that allow it to be kept within parameters to not adversely affect the livestock
> 
> I think if everyone took the no filter and no water change approach there would be carnage as not many would be able to execute it and keep it a good environment for livestock and plants alike
> 
> It's just something different and nobody is saying it can't be done, far from it, but a filter and water changes allow a safety net for me to ensure I'm doing what I can and one that I wouldn't be comfortable without



Point taken, but I would argue that both ferts and co2 are not easily measurable at all, and you’re in the same boat in terms of trying to predict these levels as you would be trying to predict what levels of oxygen are suitable for fish.  

The other thing I would argue is that I would trust aged aquarium water over anything that comes out of a tap.  The daphnia can be used to support that feeling as I’m almost certain they would not survive in a tank as you describe.  

We have gone slightly of piste from the original point but as I said it is all interrelated.  I know Darrel mentioned that they use daphnia as a measure of water quality in some work streams.  Low oxygen would be related to a high BOD which equates so poor water quality. 

I don’t think the oxygen levels in this type of tank would fall as low as one would think.


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## dw1305

Hi all, 





Soilwork said:


> but I would argue that both ferts and co2 are not easily measurable at all.....The other thing I would argue is that I would trust aged aquarium water over anything that comes out of a tap.


I would agree with that. I'm not a CO2 user, I use a method which reduces fertiliser input and I've used rain-water since the 1970's. 





Soilwork said:


> I know Darrel mentioned that they use daphnia as a measure of water quality in some work streams


 I do, mainly for the water butts. They are used in the bio-assay for water borne pollutants, but I think their tolerance of low of low oxygen levels would be higher than for a lot of fish. I'll find a reference with some figures.





Soilwork said:


> I don’t think the oxygen levels in this type of tank would fall as low as one would think.


It is really back to <"Donald Rumsfeld"> and "best guess".

cheers Darrel


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## Affinis

Hi everyone,

Just to clarify things a little, the little filterless tank Soilwork posted above is one of my playthings. 

It’s now just over a year old, just 8cm of sand, tap water, and light, no ferts or water changes. 

I’ve had good success with this kind of aquaria over the years, but it’s really only suited to small rather shallow aquaria.
Larger setups generally require a small amount of circulation in my experience. 

Going back to what Soilwork was saying about filterless tanks, I recently turned off the power filter on a very long established tank. (1995) Just replacing it with a very small powerhead for gentle circulation. What I’ve found really interesting, is that almost immediately the plants responded. It was almost like an on switch. 

I’d be interested to hear any comments regarding this reaction.


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## dw1305

Hi all,
Welcome, nice tank.





Affinis said:


> .......but it’s really only suited to small rather shallow aquaria.





dw1305 said:


> If I wanted to go even lower maintenance I'd go for a wide shallow tank with a large surface area to volume ratio, the advantage of this is that a larger gas exchange surface means quicker diffusion of CO2 and oxygen both in and out. I think tank architecture is part of the reason why "BigTom's" "Bucket of Mud" has been so successful, and if you read through his journal <Tom's Bucket O' Mud - new vid page 28 | UK Aquatic Plant Society> you can see it is an absolute triumph.


Have a look at the links from <"Low tech. lighting levels....">.





Affinis said:


> I recently turned off the power filter on a very long established tank. (1995) Just replacing it with a very small powerhead for gentle circulation. What I’ve found really interesting, is that almost immediately the plants responded. It was almost like an on switch.


Can I ask what media was in the filter? And is there any possibility that anaerobic denitrification may have been occurring?

cheers Darrel


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## Affinis

Thanks for the Reply Darrel,

The tank is an old Juwel 180 and was running a rather oversized Eheim 2217 containing just coarse foams. I was interested to see if an oversized filter would indeed create conditions for anaerobic denitrification to take place, subsequently I’d deliberately not touched the filter for the ten months it was in action. To my surprise the tank has been slowly building nitrate over this period, something which hasn’t really occurred over the 24 years this tank has been set up. In fact the main reason I’ve now decided to turn it off, is to see if the nitrate accumulation will actually drop back down naturally. I should add that the only nutrient export this tank has is from the removal of excess plant material.


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## Soilwork

Affinis said:


> Thanks for the Reply Darrel,
> 
> The tank is an old Juwel 180 and was running a rather oversized Eheim 2217 containing just coarse foams. I was interested to see if an oversized filter would indeed create conditions for anaerobic denitrification to take place, subsequently I’d deliberately not touched the filter for the ten months it was in action. To my surprise the tank has been slowly building nitrate over this period, something which hasn’t really occurred over the 24 years this tank has been set up. In fact the main reason I’ve now decided to turn it off, is to see if the nitrate accumulation will actually drop back down naturally. I should add that the only nutrient export this tank has is from the removal of excess plant material.



Hi Affinis

Did you notice any other changes to anything at all with the tank during those 10 months other than accumulation of nitrate?

What is the TDS in this tank? Any change in the 10 months?  

Lastly, do you have any pictures of the 180? 

Regards 

CJ


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## dw1305

Hi all, 





Affinis said:


> I should add that the only nutrient export this tank has is from the removal of excess plant material.





Affinis said:


> To my surprise the tank has been slowly building nitrate over this period, something which hasn’t really occurred over the 24 years this tank has been set up.


That is strange, it may be to do with the lack of water changes. This could have led to a deficiency of one of the other <"essential nutrients">.

Personally I don't often measure NO3, it is <"more problematic"> than most forums acknowledge.





Soilwork said:


> What is the TDS in this tank? Any change in the 10 months?


That is the next question for me as well, did you measure the change in conductivity (TDS) during the 10 months?

cheers Darrel


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## Soilwork

dw1305 said:


> Hi all, That is strange, it may be to do with the lack of water changes. This could have led to a deficiency of one of the other <"essential nutrients">.
> 
> Personally I don't often measure NO3, it is <"more problematic"> than most forums acknowledge.That is the next question for me as well, did you measure the change in conductivity (TDS) during the 10 months?
> 
> cheers Darrel



Hi Darrel.

Could it simply not be that a large filter such as the 2217 is encouraging nitrification because the flow takes the ammonia production directly through the media? 

I’m not questioning that their would be equal  quantities of microbes in certain areas of the tank but it would make sense that the most nitrification would take place at the media site because it is quickly and constantly being taken there.  In the case of high flow rates and filter material surely this is removing some of the plants access to ammonia.  That would be my hypothesis on why there was an almost immediate response to the filter being removed and why they may use more oxygen.  This brings me personally back to my original question.  Why filter? Maybe most people just haven’t tried it this way as a test.


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## Affinis

The tank has been ticking along nicely over this period, zero algae for example, but plant growth hasn’t been as fast as in previous years. It’s obviously been running rather lean, even the duckweed had become very small and was hardly growing.

Over this period the TDS has dropped slightly from around 400, to 342 today, but this is no surprise because I’ve only been using rainwater for top up since Xmas. Evaporation is minimal on my tanks because they’re well covered and not heated.

The last water change on this tank was 50% Xmas 2017, and previous to that five years earlier. It’s probably only had a handful of water changes since 1995.

Another thing I’ve noticed since I turned off the filter, is that the TDS is now falling much faster. But I guess that’s down to the marked increase in plant growth.

As you can see it’s not a highly manicured tank, most of the plants are the originals from 1995. I really just let it do it’s own thing, and just pull out excess when it becomes too chaotic. Sorry rather poor iPad pic.


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## dw1305

Hi all,





Soilwork said:


> Could it simply not be that a large filter such as the 2217 is encouraging nitrification because the flow takes the ammonia production directly through the media?........ In the case of high flow rates and filter material surely this is removing some of the plants access to ammonia.


Yes certainly could be, if you have plenty of oxygen in the filter then conditions will be suitable for nitrification to occur.

The volume of the filter is actually relatively unimportant, oxygen (so flow in this case) is the really important metric. You just don't need a huge volume of filter media to support nitrification. If you think of the <"rotating arm trickle beds">, or <"rotating contactors">, at older style sewage treatment they cover a relatively small area. 

It is quite difficult to quantify exactly where the ammonia is being oxidised, you could measure it quantitatively via  <"isotopically labeled tracers ([15N]ammonium to [15N]nitrate)">, but I'm not aware of any research that has looked at planted aquariums. 

There are some <"mesocosm studies"> in constructed wetlands. This from the linked paper 





> Each system was dosed with a single pulse of 15N ammonium mixed into the feed wastewater, and the fate and transport of the isotopic nitrogen were determined. The 15N pulses took 120 days to clear the heavily loaded field-scale wetlands. During this period small reductions in 15N were attributable to nitrification/denitrification, and a larger reduction due to plant uptake. Mesocosm tests ran for 24 days, during which only 1–16% of the tracer exited with water, increasing with N loading. Very little tracer gas emission was found (∼1%). The majority of the tracer was found in plants (6–48%) and sediments (28–37%). These results indicated a rapid absorption of ammonium into a large sediment storage pool, of which only a small proportion was denitrified during the period of the experiment. Plant uptake claimed a fraction of the ammonium, determined mainly by the plants requirement for growth rather than the magnitude of the nitrogen supply.





Affinis said:


> As you can see it’s not a highly manicured tank, most of the plants are the originals from 1995. I really just let it do it’s own thing, and just pull out excess when it becomes too chaotic.


Perfect, plant growth still looks pretty good. 





Affinis said:


> Another thing I’ve noticed since I turned off the filter, is that the TDS is now falling much faster.


I'm not sure about that, but I can't think of any other reason.

Keep up the good work.

cheers Darrel


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## Affinis

Thanks Darrel,

I’ll keep an eye on things, and report back in a few months.

At the moment my intention is to let the TDS slowly drop. But I haven’t decided how far to let it go, before I go back to using tap water for top up. Being in Essex, I’m not used to dealing lower levels, although I do have one experimental tank that’s currently running at a TDS of just 12.


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## Soilwork

Affinis said:


> Thanks Darrel,
> 
> I’ll keep an eye on things, and report back in a few months.
> 
> At the moment my intention is to let the TDS slowly drop. But I haven’t decided how far to let it go, before I go back to using tap water for top up. Being in Essex, I’m not used to dealing lower levels, although I do have one experimental tank that’s currently running at a TDS of just 12.



Hi Affinis,

How is the low TDS tank doing and how does it compare to the 180? 

Cheers
CJ


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## Affinis

Hi Soilwork

My low TDS tank is just an experiment really. I’d rather neglected it during the summer, so it’s a bit of a mess currently.
I was playing around with zero flow, but I’ve had a cyano issue, so I’ve recently put a very small circulation pump back in. 
On the plus side the Salvinia and Ambulia grow like crazy and the water quality is amazing. 

Although the tank is very untidy it grows just as fast if not faster than the 180, and if you ignore the cyano, it’s absolutely algae free. Even the glass stays spotless, unlike the hard water 180.


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## CJayT

Little late, but I've ran 2 successful nano tanks this way, no filter, ferts and with and without Co2. Light was just shy of medium too. Surface agitation seems to help alot though. The tank is pretty well stocked with fish though and they're fed regularly, so the water gets some nutrients from the fish food.

Second pic is pretty newly planted. Not grown out much yet
...


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