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Discussion Starter · #1 ·
Below is a recent letter I received:

"I bought your book "Ecology of Planted Tank" on Amazon Kindle. It is very helpful. I started a basic fish tank for my daughter without any plants, but the first two sets of fishes didn't do well. After doing some search on google and youtube, I came across your book and methods. I started all over using the Walstad method. One thing I am not that clear about is whether to have filter or not in a planted tank. I read in you book that filter could deplete CO2 in tank. Also, how long does a substrate last until it can't produce anymore CO2. If you could please elaborate on that that would be great."

My answers:

Good you are starting a planted tank. Many purchased fish are either severely stressed, diseased, and/or genetically weak to begin with. So choose carefully where you buy your fish!

The answers to your questions are inside my book, so read it carefully.

Read about fish food as a source of plant nutrients to replenish the soil in my book's Chapter V ('Sources of Plant Nutrients'.) How long the soil lasts-- 6 months or 10 years-- depends on how much you feed the fish (nutrient input) versus tank cleaning (nutrient removal).

How much filtration? Plants purify the water so you only need filtration for water circulation or to remove particles (mechanical filtration). In a new tank with an organic soil, you may need to temporarily provide oxygen to fish, as soil bacteria will consume lots of oxygen and pump out loads of CO2. However, you may not even need a filter. I have small tanks (5, 10 gals) and 1 gal bowls with no filtration or just gentle air bubbling. Filters lend themselves to bigger tanks to distribute heat, oxygen, and nutrients. I have a small pump filter in each of my two 20 gallons.

For small setups of 5 gal of less, I probably would start out without a filter. Of course, if fish start gasping at surface, you will need to add some form of aeration. Remember that oxygen stimulates bacteria to produce CO2, so gentle water circulation can actually improve CO2 levels for plants.
 

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Greetings!

I am using a hang on back filter in 29 gallon tank. I added duckweed and water lettuce as per the suggestion in the book. The back filter is causing some problems to the floating plants by pushing them down and sucking them up through intake strainer. I would like to turn off the filter and see if my fish and shrimp do OK. If I remove the filter, will I kill the bacteria in the substrate? Will I disturb the cycle in any way? If there is any damage to the cycle can it be reversed by adding bacteria?



Thanks!
 

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A planted aquarium is very different from a non-planted tank, where filters are concerned. All aquariums can use a filter, as a filter - something that keeps the water clear by removing the very fine debris that make the water hazy. A non-planted tank also uses a filter as a home for the bacteria that convert ammonia to nitrites to nitrates, and without that home it is possible for the ammonia and nitrites to build up enough to damage the fish. Plants use ammonia as a fertilizer, a source of bioavailable nitrogen, so planted tanks don't really need a filter to home the nitrogen conversion bacteria, and that applies to El Natural tanks, too. All aquariums have colonies of those nitrogen conversion bacteria on the plants, on the hardscape, the glass, the substrate surface, etc. So, the filter isn't the only home for that bacteria, and removing the filter won't cause permanent ammonia problems even if it does cause a temporary increase in ammonia in the water.
 

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The picture of your tank was not accessible so I couldn't see what is going on. :(

In the meantime, spillway filters are not necessary. For the first few months they might be okay, but later on the CO2 degassing will probably hinder your plants.

I would think of ways to keep the floating plants safe, like making a little floating ring out of air-line tubing. This is where the tinkering part of aquarium keeping comes in.
 

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@dwalstad & @hoppycalif,

Thank you so much for your replies. I am little hesitant to remove the filter. Will the bacteria in the substrate and tank die if I remove hang on back filter because of lack of oxygen?

I added some wooden floating sticks as shown in the image to keep duckweed away from the falling water, but two of my shrimp keep sitting on those and drown them. They seem to love that place for some reason :D. So I got rid of floating sticks.

I am posting the image again. I hope it works.
 

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My 29 gallon NPT has had the same subtrate for at least 9 years. The plants - mainly crypts - are growing profusely and could be pruned every 2 weeks. Today there are about 20 Endlers in it.

My management style is "benign neglect." Every year of so I siphon out some mulm; the plants hide the most of it. Dead fish? A great source of protein - I never see them.

I think the substrate has long since changed from topsoil to clay.

Bill
 

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Discussion Starter · #7 ·
Got picture now.

What a pretty tank! Nice assortment of plants.

That's funny about the shrimp crawling on the sticks. Sunning themselves?

As to the spillway filter, no hard and fast rules. Right now the soil is probably pumping out plenty of CO2. Also, sometimes freshly submerged soils create an oxygen deficit for a couple months.

Spillway filters are okay if there is not a lot of water churning and bubbling. It is vigorous air-water mixing that degasses off precious CO2.
 
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