# Biological Filtration and Plants



## Plattykins (Apr 3, 2005)

Just finished reading Diana Walsted's article about plants and biological filtration at:
http://www.aquabotanic.com/plants_and_biological_filtration.htm

I was surprised to read that plants take up ammonium (especially through their leaves) more readily than nitrates. Hence there is competition for ammonium by both biological filters and plants. I have always read that plants take up nitrates after being converted from ammonium. Rather, according to the article, plants must first convert nitrates back to ammonium in order to take advantage of the nitrogen source. This is the basis for removing biological filters from the tank and providing only a pump to ensure water circulation.

I have often considered removing the biological filters from my tanks; however, I am not certain that my ratio of fish to plants is such that problems would not arise for the fish. I am interested in what others have to say about the article and about using planted tanks as their own filters, rather than including biological filters with planted tanks.


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## Phil Edwards (Jan 22, 2004)

Plattykins,

Ammonium (NH4+) is much closer in structure to an Amine group (NH2) which is used to make proteins than Nitrate (NO3) is. Because of that plants are able to utilize NH3/NH4 more easily than NO3 and will compete with an "artificial" biological filter mechanism such as a Bio-Wheel or ceramic tubes. Plants are a very efficient and effective biological filter and most folks are more than happy to use them as such. Personally, I remove most of the biological filteration mechanisms from my canister filters, except for a little to act as a gross particle filter. Even with very high bioloads a healthy, heavily planted tank will soak up just about all of the NH3/NH4 put out by the fish/feces as soon as it's in the water column. 

In nature NH3/NH4 is almost non-existent because so many things suck it up as fast as they can, so most plants have adapted to using NO3 as their main source of nitrogen. However, they do have to convert it to some NH(X) form for use in protein synthesis and that does take some energy to do. Go right ahead and slowly phase out that bio media and watch your plants grow! If you remove it too quickly (ie, all at once) you'll probably get some algae problems as the tank adjusts. 

Regards,
Phil


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## Plattykins (Apr 3, 2005)

Thanks for the information and for the encouragement Phil. I will give it a shot! How frequent are your water changes?


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## trenac (Jul 16, 2004)

Plattykins... I tried once removing the bio-wheel from my filter and got a major bacteria bloom. Phil advises to do it slowly so maybe that was the problem I had, since I removed the whole wheel at once. 

With that said you can use your plants as the biological filter. I just feel safer having some bio-media in my filters, I guess that comes from my years of having non-planted tanks. 

Don't be afraid like me and go ahead and give it a try and see what happens. Let us know how it goes.


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## MiamiAG (Jan 13, 2004)

Plattykins,

I do a water change every month or two. All I use for filtration are the plants and the bacteria that colonize everything in the aquarium. I do not use a separate filter (e.g., canister filter).


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## RedDelPaPa (May 18, 2005)

Plattykins said:


> Just finished reading Diana Walsted's article about plants and biological filtration at:
> http://www.aquabotanic.com/plants_and_biological_filtration.htm
> 
> I was surprised to read that plants take up ammonium (especially through their leaves) more readily than nitrates. Hence there is competition for ammonium by both biological filters and plants. I have always read that plants take up nitrates after being converted from ammonium. Rather, according to the article, plants must first convert nitrates back to ammonium in order to take advantage of the nitrogen source. This is the basis for removing biological filters from the tank and providing only a pump to ensure water circulation.
> ...


Surprise, surprise huh?  Did you, or anyone here happen to read my post: "Growing plants in tanks with heavy bio filtering?"

My 15 years of experience says bio filtering is bad for plants. Especially UGF's.

Plants do prefer ammonia(um). And therefore, will grow better if it's available to them. That is my firm belief.

RedDelPaPa


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## MiamiAG (Jan 13, 2004)

Red,

I must have missed your post. I'll go find it. I tend to agree with you. However, I always tell newbies that some bacterial filtration will give them a buffer. 

More advanced growers can and, perhaps, should go without the added filtration. I'm running an aquarium with around 15 fish (7 of them swordtails/platys) without a separate filter.


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## RedDelPaPa (May 18, 2005)

Art_Giacosa said:


> Red,
> 
> I must have missed your post. I'll go find it. I tend to agree with you. However, I always tell newbies that some bacterial filtration will give them a buffer.
> 
> More advanced growers can and, perhaps, should go without the added filtration. I'm running an aquarium with around 15 fish (7 of them swordtails/platys) without a separate filter.


Mother nature designed a far superior filter to anything mankind could ever produce. They're called, plants. Plus, they look better, and they're a heck of a lot quieter.


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## Plattykins (Apr 3, 2005)

Art - once a month?? wow! I just got in the habit of once a week.  I was at once a month or less prior to that, then I discovered the Nitrate test. chuckle. It got me on to once a week fast and I have adjusted the amount I feed. 

As for the number of fish in the tank, that is encouraging. My 25 has 8 Rasboras, 8 Platys, a dozen Swordtails and misc fry. At least 1/2 dozen of the Swordtails are going to the LFS shortly, as I am slightly overstocked. The Swordtails have been a steady source of credit at the LFS for the last several months. This is the tank I was concerned about most when moving to filterless because of the number of fish.

trenac - Tonight I removed 1 of two sponges from the HOB's on my tanks and took readings. It will be interesting to see how it goes over the next several days. You said, don't be afraid, but I have to say I've thought about it for some time... rather like taking the training wheels off my bike when I was a kid... ok, maybe not that bad! LOL

Red - I will look up your article as well. btw, I have air stones in the tanks and I have not decided whether I will keep the air stones or use a powerhead. Not sure if I can get enough circulation with air stones, but what did folks do before there were powerheads anyway? LOL. I had just begun to realize that I could maintain a balance between the plants and fish, when I began finding articles about filterless tanks. I never expected the ammonium aspect. It made me realize I've been working my plants too hard.


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## MiamiAG (Jan 13, 2004)

Plattykins,

I follow Edward's PPS method that doesn't require resetting the tank with weekly water changes. Works better with my busy schedule.


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## RedDelPaPa (May 18, 2005)

*I just thought of something*



Plattykins said:


> Art - once a month?? wow! I just got in the habit of once a week.  I was at once a month or less prior to that, then I discovered the Nitrate test. chuckle. It got me on to once a week fast and I have adjusted the amount I feed.
> 
> As for the number of fish in the tank, that is encouraging. My 25 has 8 Rasboras, 8 Platys, a dozen Swordtails and misc fry. At least 1/2 dozen of the Swordtails are going to the LFS shortly, as I am slightly overstocked. The Swordtails have been a steady source of credit at the LFS for the last several months. This is the tank I was concerned about most when moving to filterless because of the number of fish.
> 
> ...


After reading that article, you find out that plants will use nitrates if they have to, but not by choice. And if being forced to use nitrates, it requires energy from the plants in order to convert the nitrates back into ammonium in order to build the plant proteins. I'm assuming this energy to do so more than likely comes from the lighting. This could be me and my Dad's Achilles heel. We have never followed the lighting guidelines. We have never needed to. For example, I have a 75 gal with 80 watts of florescent lighting. 2x 40 watt 48" full spectrum tubes. By any guideline, this is rock bottom. However, to me, it's plenty. Maybe even to much. I have floating hornwort that covers almost the entire surface of the tank. The light up there is so bright, that my hornwort is super thick and red almost 1" deep. And rooted in the gravel, I have a species of plant with one of the highest light requirements of any aquatic plant. Or so they say. Straight Val. And it's growing like crazy and bright green. It looks great. So to me, I feel I have plenty of light. And in this tank, I have no bio filtering other than what's on the surface of everything in the tank. Which you can't do anything about. The only filtration I ever use is a HOT AC500 for mechanical filtering only. And only when needed. Maybe once a week. And I dry out the media after use. So there is no nitrifying bacteria present. This tank is stuffed chuck full of juvi malawi cichlids, and adult swordtail's and guppies as dither fish. No air stone, and the tank has glass tops in place to help keep CO2, heat, and evaporation in, and surface scum out.

To conclude, I have come up with a new theory. Just maybe, when the plants do not have ammonium available to them, due to heavy bio filtering, and they're forced to use nitrates, they're not receiving enough energy through light, than they are having to expend in order to convert NO3 back to NH4 to produce plant proteins. Therefore, they are caught in a life threatening situation, and slowly wilt away and die?

Red


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## AaronT (Apr 26, 2004)

I've started running my 75 gallon tank with just some bioballs in the canister filter. Whenever I need to remove particulate matter from the water column I run a power head with a quickfilter. I have 32 rummynose, 12 ember tetras, 15 diamoad tetras, 12 false panda cories, and several shrimp and snails. The fish and plants are doing great.


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## Plattykins (Apr 3, 2005)

So how 'bout posting pics of some o' these filterless tanks for our enjoyment?

Red, I'm going to have to do some reading to catch up to your last question I think!  Sounds about right tho, as far as light, energy... making me think back to biology class. Unfortunately, that was many years ago. I know there are some folks here that can fill in the gaps.


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## AaronT (Apr 26, 2004)

My tank is in collector farm mode for the time being. I'll post pics when it looks better.


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## Phil Edwards (Jan 22, 2004)

Plattykins said:


> Thanks for the information and for the encouragement Phil. I will give it a shot! How frequent are your water changes?


It totally depends on what I'm trying to do with the tank. If I've got an Aquatic Garden that I want to enter into a competition I'll do water changes once a week to give a buffer for all the nutrients I dump into it. Other tanks might not ever get a water change and may not even have a filter on them. Most of my tanks don't have fish so I don't feel the need to do water changes all that often as long as the plants are doing well.


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## Piscesgirl (Feb 25, 2004)

Here's my filterless 20 gallon long tank, although it is by no means an aquascaped tank (none of mine are at the moment). There are 3 adult Killifish and one juvenile (although he's approaching adulthood it seems as they grow up very fast). I run DIY Co2 and an airstone 24/7. I keep the center clear so I can see the fish, but the rest of the plants are left to grow jungle style. I do, however, do approx 40 to 50 percent water changes, weekly.


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## Plattykins (Apr 3, 2005)

Phil, 
thank you for the info. It makes sense now.

Piscesgirl, 
nice photo. Lots of plant growth there. I like it. Thank you for the info. I am working on pulling the 2nd of two sponges from my filters today. I am keeping the filter without media to provide circulation instead of a powerhead at the moment (in the 25 gallon so far). At some point, I may try to keep just the airstone (and my cheesy diver guy) running. It will be interesting to see if the water changes become less or more frequent. 

Little by little...slow but sure. I have been tracking everything in my journal here on APC. Still have the 10 and the 30 gallon to convert yet.


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## Piscesgirl (Feb 25, 2004)

I was glad to share it  I had been thinking quite a lot about filters/no filters approximately a year ago -- this tank ran with two clown loaches for several months as well before the Killifish. I was thinking about power outtages and why would I want my beneficial bacteria in a box that was OUTSIDE my tank? So, when the power goes out, it goes anaerobic and can even foul the water when it starts back up. More I thought about it, I figured filterless would be my version of the safest for my fish -- but I also have back up air pumps on the tanks which go on when the power goes off. However, I haven't had the guts to try it with the other tanks, especially the 55 with a large bioload.


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## Plattykins (Apr 3, 2005)

"...and why would I want my beneficial bacteria in a box that was OUTSIDE my tank?" - Piscesgirl

[smilie=l: yes, sometimes looking back is funny. I guess it just depends on how you view things... that is, how you view the way things work and/or how you want to run your tanks. I must say, removing the filters is quite liberating, but as the hours go by, it is an anxious liberation. I have a heavy fish load in the 25 gallon, so I figure if something is going to go haywire, it will there. So I converted that one first and am keeping a close eye. A month from now, I will look back and chuckle at how huge this seems to me now. But I also think about how much I am relying on the plants .. trusting the plants to do their thing before I had a couple of improvements in place, such as glass tops and additional lighting. What's more is, I've been running my snail tank this way for months without giving it a thought.


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## Piscesgirl (Feb 25, 2004)

I understand the anxious part. If I don't do my water change exactly at one week since the last, I start to get very anxious -- as extra days go by, I keep looking at the tank, worrying. Usually then I can't stand it any more and do a water change.  In fact, today is a week and I'm thinking of testing the NitrAtes in a bit to see where they are!


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