# Hydroponic Plant Filtration



## Wasserpest (Jun 12, 2003)

I have done Monstera, it works well initially, but just keeps growing until, well, your tank is full of roots. Eventually your biofilter will be a solid mass of roots. But yeah, Philodendron is an excellent plant for hydroponic culture and (bright) room light levels.

Others have done the hydroponic thing with Peace lilies, and if you look up the various Riparium setups (Journal section?) you might get some more inspiration.

Two things to keep in mind... Planted tanks usually need to be fertilized, so adding terrestrial growers around the tank will increase those nutrient dosing requirements. And second, if you want a good-looking underwater landscape as well, think about sufficient light going towards the deep. Often the terrestrial plants grow too well and shade out the submersed part, which leads to problems down there.


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## lauraleellbp (Feb 3, 2008)

Check out Hydrophyte and Hoppy's riparium threads (there's others doing them now, too- just plug "riparium" into the forum search engine, or do an advanced search, enter their name and search for their threads) plus yikesjason's plant wall over his discus tank: http://www.plantedtank.net/forums/t...29-yikesjasons-150-wide-discus-tank-11-a.html


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## DGF (May 4, 2010)

some cool stuff here:

http://www.tuncalik.com/2009/07/my-aquariums-at-home-july-2009/


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## Mxx (Dec 29, 2010)

Just to clarify, I'm not interested in doing a terrarium or riparium, which is also why I didn't post this in that section. 

And as much as I like the open top rimless tanks, I'm not so keen on how their suspended lighting works with the rest of a room. I'd much prefer to have my 'houseplants' separate from my tank plants. And as the roots would be growing behind the background I'm not concerned if the roots grow to be substantial, in fact I'd be happy if they did as that means they'd be doing their job extremely effectively! Nevertheless, I don't want to see the roots. 

Yikesjason's plant wall was quite good. I think I'd prefer a monocolture of plants with leaves of a very large scale appropriate in proportion to a 200-300 gallon tank. Wasserpest, how large were your Monstera leaves getting to be? S

eems like a good idea in any case. Looks good, low maintenance (or actually reduces maintenance if it reduces the need for water changes), and improves indoor air quality as well, right?


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## WallaceGrover (Jan 15, 2011)

Regardless I believe what you're trying to do is a riparium whether you want to call it that or not...


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## lauraleellbp (Feb 3, 2008)

So basically, the back of the big tank would be a sump, with the plants growing directly out of the sump area? 

They sell "plant scrubber" filters over in Asia that incorporate a similar design... I remember reading through a thread over on TFH with one, lemme see if I can find it...

EDIT- I can't find it. Was a really really long time ago. From what I remember, it was a waterfall-type filter that ran lengthwise across the top of a tank. Intake on one side, waterfall output on the other. The big, open air middle compartment contained filter media and a plastic grate on top of the media to rest potted plants on. Sounds somewhat similar to what you're describing?


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## Wasserpest (Jun 12, 2003)

Mxx said:


> Wasserpest, how large were your Monstera leaves getting to be? Seems like a good idea in any case. Looks good, low maintenance (or actually reduces maintenance if it reduces the need for water changes), and improves indoor air quality as well, right?


Leaf size of Monsteras depends mainly on light levels. With indirect light, they maxed out at 12-15in. Obviously, with high light or direct sunlight, plenty of nutrients, and perhaps a bit of humidity they will become Monsters.

I still think that if you want a nice planted tank, adding terrestrial plants will be detrimental.


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## Mxx (Dec 29, 2010)

Yes, a 'plant scrubber' is essentially what it would be. I'd been trying to simplify the filtration design as much as possible, which is where I'd come to the conclusion that a massive in-tank rear bio-sump would be best. A bio-filter and tank plants might not deplete the phosphates though, if for instance I was trying to raise mid-size discus and had to do a heavy feeding routine, which is why I though extra plants would help and wouldn't be CO2 limited in case I got tired of trimming and decided to tune that down. 

An HOB waterfall filter I suppose would be similar. I wouldn't want pots sitting on top of the rear though, as I'd looking to achieve a relatively low-profile hood.

12" Mostera leaves would be great actually, as long as they're not double that. Detrimental how? I'd want to use MTS for the tank substrate, so that I wouldn't need to be dosing all the time. And if the Monstera/Philodendron would do okay with just the nutrients they'd be exporting out of the tank then that'd be ideal. But if not then having them rooted through pots sitting in the sump which I could dose with root tabs would still be easy. As they'd be sitting over the tank's lights they wouldn't be limiting the light reaching my tank's plants. Originally I was thinking of using floating plants like Salvinia, but then I though overhead vines might be work and look better.


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## lauraleellbp (Feb 3, 2008)

Detrimental = big leaves will block light from the aquatic plants. They'll also compete with the aquatic plants for nutrients, so you'll have to up your fert dosing to compensate.

With a 300gal tank you may have enough tank depth to be able to get light to the front of the tank, but you'll probably have to keep up with the pruning/espalier technique.


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## Mxx (Dec 29, 2010)

Judging by responses, I may not have explained this correctly. The water in the aquarium would be filled up all the way to the brim, and the tank's lights would be sitting right on top of the tank. So the Terrestrial plants would be altogether above the tank's lighting and wouldn't therefore have a chance to block it in any way. 

I wouldn't mind dosing some fertilizer as necessary of course, but would prefer to run a tank which is lean on nitrates and phosphates as much as possible, in order to keep up with fish waste from moderate stocking densities without resulting in algae, etc.


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## lauraleellbp (Feb 3, 2008)

Ahhh- yes that does make more sense in regards to the lighting.

It will be a balancing act in terms of nutrient supply, but I think it should be workable.

I assume if you want to minimize fert dosing that you're planning on a low light tank as far as the aquatic plant portion?


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## Mxx (Dec 29, 2010)

I was under the impression that MTS would lessen or eliminate the need for fert dosing? (A slightly different topic, but one which I'm yet to bottom out). Wasn't sure about the light levels actually. I was planning to have CO2 anyway, and it may very well depend upon the chosen plant's requirements, but possibly medium lighting. I was thinking to try and match high bio-loading with high plant growth and high lighting. The floating plants would have cut down the lighting significantly and would have been easy enough to harvest in order to export nutrients, (in case I'm planning to do water changes only as minimally as proves necessary to maintain high water quality, again a different topic). 

Any other potential pitfalls to try and plan around with a plant scrubber though? I'd thought that the combination of MTS, heavy tank planting, and a large terrestrial plant scrubber would potentially be the best combination to avoid algae, as you could try and limit any nutrients in the water column without compromising the growth of either set of plants.


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## Wasserpest (Jun 12, 2003)

Reading your posts it appears that you think by limiting nutrients you will avoid algae growth. This is a common misconception when it comes to planted tanks. Limiting nutrients will hinder growth of the higher plants and give algae a chance to thrive.

MTS will supply some nutrients for a while, but I don't think it will be sufficient in a high light/fast plant growth tank, especially for stem plants.

All good questions... it's a rather complex game, and the "high bioload balanced with high lights and plant mass" theory often doesn't work out in the end.


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## Mxx (Dec 29, 2010)

Wasserpest said:


> Reading your posts it appears that you think by limiting nutrients you will avoid algae growth. This is a common misconception when it comes to planted tanks. Limiting nutrients will hinder growth of the higher plants and give algae a chance to thrive.
> 
> MTS will supply some nutrients for a while, but I don't think it will be sufficient in a high light/fast plant growth tank, especially for stem plants.
> 
> All good questions... it's a rather complex game, and the "high bioload balanced with high lights and plant mass" theory often doesn't work out in the end.


Haven't read Walstead's book yet and I know there is a great deal more complexity to this. I thought the general theory was to use phosphates as the limiting factor as plants are more successful than algae at utilizing this. And that as the MTS sub-substrate is available to the plants would not the algae, the plants would thrive as they're rooted in a rich base of everything they require, while algae might even be limited by several different factors. But I'm not sure how far you can push this theory in practice of course. And I would probably be avoiding stem plants, unless I do decide to try Limnophila aromatica. 

What would be your best recommendation for success then in this specific set of circumstances, in case that's not too general a question? I'm trying to design out any potential problems in advance as much as I can, which is why I'm trying to work out solutions such as plant scrubbers.


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## Wasserpest (Jun 12, 2003)

Mxx said:


> Haven't read Walstead's book yet and I know there is a great deal more complexity to this.


I have, and didn't feel much enlightened afterward. It has some interesting tidbits in it, but also a lot of stuff that isn't really that essential for the regular planted tanker. I am selling my copy! :icon_bigg



Mxx said:


> I thought the general theory was to use phosphates as the limiting factor as plants are more successful than algae at utilizing this.


That isn't the general theory. It is one theory that two gentlemen (Sears and Conlin) published in some paper quite a while ago, which was then widely distributed. It might have worked for a few folks, but since then it has been found that limiting P does more harm then good. It's not quite clear why, but if we supply all nutrients in sufficient quantities, plants usually grow well and algae growth is suppressed. If you google Liebig's Law you can get a more graphical idea of the principles behind that.



Mxx said:


> And that as the MTS sub-substrate is available to the plants would not the algae, the plants would thrive as they're rooted in a rich base of everything they require, while algae might even be limited by several different factors. But I'm not sure how far you can push this theory in practice of course. And I would probably be avoiding stem plants, unless I do decide to try Limnophila aromatica.


This can work very well for low light/low tech setups, and initially for higher light as well, provided CO2 is supplied. It's a bit difficult though to know and monitor the nutrient situation in your MTS, and with faster growth and usage, something is going to run out sooner or later.



Mxx said:


> What would be your best recommendation for success then in this specific set of circumstances, in case that's not too general a question? I'm trying to design out any potential problems in advance as much as I can, which is why I'm trying to work out solutions such as plant scrubbers.


Let's step a step back and risking some repetition, look at your second goal:



> 2. Have these plants assist in my tank's filtration by absorbing extra ammonia/phosphates/nitrates.


This could be a good approach in an overstocked tank with a few plastic plants. However, for some reasons it doesn't work as well in a normally stocked planted tank. Mostly because there is no extra N/P/NH4 available.

The logical conclusion could be to load the tank with fish to get some nice high Ammonia and Nitrate levels. Doesn't work so great either. High biomass can cause many problems in an enclosed container. For example, there's going to be a lot of biofilm on all the surfaces, including plant leaves, which naturally attracts a lot of algae and deters plant growth (photosynthesis/respiration/gas exchange). Also, you don't know that the fish excrements/spoiled fish food will be exactly what the plants are going to eat that day, and with a low water change approach things will build up to toxic levels sooner or later.

What I would suggest would be to stock your tank normally, ideally with small fish that are plant friendly. Plan on doing water changes, possibly automated so you don't have to remember or even think about them. Fresh water is one of the best things for fish and plants. Check out water column dosing. It's not that complicated really, and does a lot of good for our plants, while keeping algae at bay.

Of course, in the end you will do whatever you decide. Sometimes we just have to try out something, even if someone else advised against it. Amazing things have come out of that. :bounce:


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## Mxx (Dec 29, 2010)

Well bugger that! I was hoping I might be able to get down to the bottom of some definitive answers and know exactly what target parameters I’m aiming to achieve before I plunged into this. Very helpful and thankfully specific advice though, so thanks! But unfortunate if none of us has definitive answer to some of these matters. I suppose I’ll have to just give it my best shot with my set-up and improvise accordingly as I go along. 

I’d heard someone else mention that limiting phosphates wasn’t helpful, which is another topic I’d meant to look into at some point in greater detail. 

I might be dosing some nutrients into the water to help get all the planting rooted and to achieve some growth quickly, but from there on I’d like to start slowly dialing down the lights, CO2, and dosing. And I guess that later on I’d start seeing some signs if and when something in the MTS became depleted and could react accordingly then. 

What I’m looking to achieve actually goes against all usual advice I’m afraid. I’d be trying to grow out mid-sized discus in a planted tank, which requires heavy feeding and usually very heavy water changes. I could hold off on stocking the rest of the fish that I’d eventually plan to add until the discus have grown out though. But with as heavy of feeding as I could manage, I’d like for the plants and filtration to be able to handle all the waste produced. And that’s why I was looking at using a 30-40 gallon biological filter including denitrifying medium, and a plant scrubber. I’d rather err on the side of caution with the system, and if my ammonia/nitrates/phosphates are too low then I’d prefer to dose those only as need be. So I wouldn’t actually be overstocking the tank necessarily, but I would be feeding my light fish-stocking loads heavily at first.

And I appreciate that many wouldn’t agree with this approach at all, but I think there is still a healthy and complementary balance that can be found there between the needs of plants and fish. And I’d be doing water changes as water conditions prove necessary in addition to remineralizng, although I’m still unsure as to what parameter should supposedly be the determining factor for that if nitrates are not what are building up. 

I’m not sure what the bio-film you mention is though. I thought it would be most advisable in any case to utilize an ozoniser with a reaction chamber as well, in order to strip down any dissolved organic compounds through oxidization into more basic forms which the plants and bacteria can consume. 

My tap water is really poor, so any water changes would require a considerable amount of wasteful RO filtering, reconstituting, remineralizing, etc, whilst I’m still not convinced that water becomes ‘broken, or stale’, in time and needs to be thrown out. So with a massive biological filtration volume, heavy submersed and emersed plant filtration, and chemical filtration through ozone and carbon, I wanted to carefully monitor how well I might be able to prevent anything from building up to detrimental levels even if my water changing system is as automated as possible. 

Hopefully with the amount of plants I’d be looking at, my fish bio-mass would still be low in relation to my plant bio-mass and therefore some manner of a natural balance might be forged to some degree. I expect that wouldn’t be perfect and would require much adjustment, but some balance is better than no balance in my personal view.


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## Sharkfood (May 2, 2010)

It's best just to completely scrap the concept of trying to eliminate phosphates. You're going to be adding phosphate to your tank if you're growing plants. 

If you plan on heavily overfeeding the fish to make them grow faster, it may be possible to be putting enough nitrogen into the tank, and maybe (but probably not) enough phosphate, but you'll still want to add potassium. Usually we add potassium into the water primarily as the other component of the mineral salts we dose to add the nitrogen and phosphate, so you would have to dose significant amounts of potassium sulphate, or something similar. Don't forget micros also.

MTS is mostly useful to plants that actually have their roots in the soil after a short initial period where leaching occurs more quickly. It's not a substitute for water column dosing.


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## yikesjason (Jul 2, 2008)

With my plant wall, I had to double up on EI dosing. But now, six months later, I think I am getting some plant decay and my levels seem to be off. I haven't done any testing to see though. 

I have not be scientific enough with my plant wall to give definitive answers. But it seems to be a good idea. The plant matrix is bulk pond filter media, so it really is a big filter since water circulates through it. I get a lot of mechanical and biological filtration from it.


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## Mxx (Dec 29, 2010)

yikesjason said:


> With my plant wall, I had to double up on EI dosing. But now, six months later, I think I am getting some plant decay and my levels seem to be off. I haven't done any testing to see though.
> 
> I have not be scientific enough with my plant wall to give definitive answers. But it seems to be a good idea. The plant matrix is bulk pond filter media, so it really is a big filter since water circulates through it. I get a lot of mechanical and biological filtration from it.


Honour to have you comment, seeing as we'd just been discussing your set-up!  And green walls/green façades are a very fashionable thing nowadays in the design world. I'd just recently had a planning official suggest that I incorporate them on a set of houses I'm working on, though I'm actually not so sure about that. Green roofs yes, but green façades are iffy to me in that instance. 

Yours in any case goes quite beyond what I'd be looking at doing, and I suppose in action serves as an effective wet/dry filter for you? Even if the plants didn't do a thing for water quality, I'd be happy if they achieved dense coverage on the wall without having to ever be watered separately. I suppose I'd nevertheless figure on having to have them rooted through a small pot of substrate such as gravel above the waters surface in which I could dose root tabs. Do you happen to know if I could fully submerse the roots of plants such as Philodendrons though?


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## yikesjason (Jul 2, 2008)

I don't know for sure about Philodendrons, but a lot of people do it with pothos, which are very similar.


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## trackhazard (Aug 24, 2006)

Mxx said:


> What I’m looking to achieve actually goes against all usual advice I’m afraid. I’d be trying to grow out mid-sized discus in a planted tank, which requires heavy feeding and usually very heavy water changes. I could hold off on stocking the rest of the fish that I’d eventually plan to add until the discus have grown out though. But with as heavy of feeding as I could manage, I’d like for the plants and filtration to be able to handle all the waste produced. And that’s why I was looking at using a 30-40 gallon biological filter including denitrifying medium, and a plant scrubber. I’d rather err on the side of caution with the system, and if my ammonia/nitrates/phosphates are too low then I’d prefer to dose those only as need be. So I wouldn’t actually be overstocking the tank necessarily, but I would be feeding my light fish-stocking loads heavily at first.


As soon as you said discus and terrestrial plants, I thought of this setup:

http://www.plantedtank.net/forums/tank-journals-photo-album/35106-kingborris-wild-discus-tank.html

It seems close to what you laid out in your posts.

-Charlie


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## Wasserpest (Jun 12, 2003)

:thumbsup: Hehe, you might even be able to go and visit!


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## Solid (Jul 19, 2009)

That tank is stunning!! but please note that he does 2 weekly 30% water changes and doses ferts.


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## Mxx (Dec 29, 2010)

trackhazard said:


> As soon as you said discus and terrestrial plants, I thought of this setup:
> 
> http://www.plantedtank.net/forums/tank-journals-photo-album/35106-kingborris-wild-discus-tank.html
> 
> ...


That's a fantastic example in certain ways of what I'd like to achieve with my display tank, and even much the same dimensions although I'd want to go a little longer. There are definitely a few things he did which I want to emulate. 

And I keep getting wildly divergent opinions here and from discus people. Many opinions seem to be that there is no way you could have a filter and plants which would keep up with the amount of waste that you get from keeping discus and from the heavy feedings necessary to raise juvenile discus. But then some plant people here are reporting that massive biofiltration including denitrification and plant scrubbers are complete overkill as the tank's plants would already deplete any of the macros such as ammonia/nitrates/phosphates to the point where I'd have to dose those regardless. What gives??? 

To be specific, I'd plan moderate fish stocking densities - not low and not high - heavy feeding, and heavy heavy plant coverage including 100% of the bottom and possibly much of the surface as well, depending upon whether or not I like the look of them in the end and whether my lighting can handle both. 

This conversation though is starting to go back to the always inconclusive question of why we do water changes and if they're even necessary. In any case, it seems to me that if you're having to dose each of the macros then perhaps the tank isn't balanced and you actually could use more fish! Perhaps dosing the micros would still prove necessary for lush plant growth, but I would hope to achieve a good balance of fish/nitrates&phosphates/ and plants as much as is possible. And it's somewhat a matter of principle for me even. I'd want to err on the side of the fish though, and have a discus tank with plants, instead of a planted tank with discus. Perhaps hardy plants would even do okay without any dosing if I was able to achieve some semblance of balance between fish and plants, (taking water changes out of the picture for the moment while considering this balance purely on its own).


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## Wasserpest (Jun 12, 2003)

I'd listen to the discus people... Not sure how the heavy feeding etc will be offset by plants.

Personally I am very pro-waterchanges :wink: since fish just happen to pee into their surroundings, and even with plants eating some of the metabolic byproducts we can't be sure that they will restore waterquality, especially if they are hindered by various other nutrient deficiencies. Unfortunately, fish excrements don't supply the exact combination/ratio of nutrients that plants need.

Do whatever makes your fish happy and whatever doesn't stunt their development...


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## lauraleellbp (Feb 3, 2008)

I'd personally grow out juvie discus in a bare-bottomed tank, and only try adult or at least sub-adult discus in a setup like this.

Juvie discus are heavy, messy eaters and I think it's just asking for algae issues as food flies and settles all over the tank, especially with a carpet of plants, and even with a heavy load of scavengers... Juvie discus and your goal of minimizing water changes don't go together. Adults would be more compatable with that goal.

I think you'll end up having to make some choices between the discus vs plants otherwise.

I'm sure others would try it and probably even have success, but I think it would be more work than I'd want to put into it.


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## Mxx (Dec 29, 2010)

Wasserpest said:


> I'd listen to the discus people... Not sure how the heavy feeding etc will be offset by plants.
> 
> Personally I am very pro-waterchanges :wink: since fish just happen to pee into their surroundings, and even with plants eating some of the metabolic byproducts we can't be sure that they will restore waterquality, especially if they are hindered by various other nutrient deficiencies. Unfortunately, fish excrements don't supply the exact combination/ratio of nutrients that plants need.
> 
> Do whatever makes your fish happy and whatever doesn't stunt their development...


Unfortunately almost all the discus people I'd heard from had almost no experience with the ecology of a planted tank. They mostly all seemed to swear by the rule of keeping their discus in bare tanks and then doing massive daily water changes because they had no other means by which to deal with nitrates. But that sort of an approach seemed rather ugly and silly to me... I suppose I could try and stick with only the sub-adult discus for the first year, and only then add to the bioload once they've reached full size.

I thought I'd try and go as overboard as possible with plants and filtration, and then let water conditions such as ammonia/nitrates/phosphates dictate to what extent water changes are required. However I'd like to have some sense of how much water changing that still might be, for if it would be very frequent then I'd want to put in some plumbing lines in advance in order to build an automated water changing system. I'd plan to dose nutrients to start out with, but then maybe reduce that later to see how well the plants do without it. And if I'm having to dose too many macros while doing only infrequent water changes then it would be easy enough to empty some portion of the filter medium to achieve a better balance (or get more fish I suppose).

I am concerned that plants and biofilter don't remove all the by-products which animals produce though, so I'm still thinking it might be best to play it safe and include an ozone system and carbon filtration in the tank set-up, just to try and reducer any other possible organic compounds to an inert state. I don't know if there actually are other compounds to worry about but thought that would be playing it safe at least.


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## Mxx (Dec 29, 2010)

lauraleellbp said:


> I'd personally grow out juvie discus in a bare-bottomed tank, and only try adult or at least sub-adult discus in a setup like this.
> 
> Juvie discus are heavy, messy eaters and I think it's just asking for algae issues as food flies and settles all over the tank, especially with a carpet of plants, and even with a heavy load of scavengers... Juvie discus and your goal of minimizing water changes don't go together. Adults would be more compatable with that goal.
> 
> ...


I do keep hearing that about juvenile discus and planted tanks, but logically there has to be a limit to the amount of waste that even juvenile discus can produce. And my goal is to have a large enough filter to handle that. I see people that run one or two standard canister filters that then state that there is no way that filtration can handle it without water changes. But what I'm looking at having is around a 30-50 gallon rear of tank sump filled entirely with 
submersed bio-medium, (probably alfagrog due to it's cheap price and denitrifying capacity), in addition to heavy tank planting and a plant scrubber. And nobody that I had heard from had anything approaching that level of filtration. I'm looking at getting at least 3.5-4" discus which are the maximum size I'm generally seeing offered. Such discus I suppose are of a decent size while not yet being ridiculously priced. I'm not sure if that counts yet as sub-adults though. I sent an email to one local breeder I'd been corresponding with asking if he could keep a tank of fish aside for me until they add another inch or two of size and at what cost, but haven't yet heard back.


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