# Filters for Small Bowls and Tanks



## dwalstad (Apr 14, 2006)

Ideally, NPTs use plants and soil to purify the water. But sometimes, it does help to circulate the water. Wild bacterial growth in a freshly submerged organic soil can pull oxygen out of the water.

That said, I have yet to find any ready solution for circulating water in a small tank or bowl. I'm sure there are products, but they are bound to be expensive.

I've got 6 tanks and 4 brine shrimp bottles. What I'm using is a small Whisper air pump, 4-way gang valves, air-line tubing and glass rods. The pumps, valves and tubing are readily available for hobbyists, but the glass rods are not. I bought a pound-life-time supply--of glass rods off of Amazon. Flint glass, OD = 5 mm; ID = 3 mm and about 2 ft long.

https://www.amazon.com/Ginsberg-Scientific-5MMSLT-24-Flint-Tubing/dp/B00FGDX3FA/ref=sr_1_3?s=industrial&ie=UTF8&qid=1524743545&sr=1-3&keywords=5mm+glass+tube&dpID=411FFzY%252BG5L&preST=_SX342_QL70_&dpSrc=srch

I cut off foot-length (~30 cm) sections and attached them to air-line tubing. (Hint: heat the plastic tubing in hot water to fit snugly over the glass ends.)

One small Whisper air pump easily takes care of 4 tanks/bottles. Attached is photo that shows the circulation setup for the brine shrimp bottles and a 5 gal tank. The yellow plastic gang valves (AccuAir) are really nice-inexpensive and they allow a fine-tuned adjustment.


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## DutchMuch (Apr 12, 2017)

Tetra Whisper Non-UL Air Pump for Aquariums 7$
Python Airline Tubing for Aquariums, 25-ft 3$
EcoPlus Round Air Stone 6$
Total: 16$


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## FromReefs2Plants (Aug 14, 2017)

https://www.amazon.com/dp/B005VEWCMO/ref=psdc_2975472011_t1_B00T6HPZFI

I've used this in the past and it worked very well for my 5.5g tank. You can turn down the flow for even smaller tanks


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## dwalstad (Apr 14, 2006)

FromReefs2Plants said:


> https://www.amazon.com/dp/B005VEWCMO/ref=psdc_2975472011_t1_B00T6HPZFI
> 
> I've used this in the past and it worked very well for my 5.5g tank. You can turn down the flow for even smaller tanks


Thanks for the helpful input.

A note of caution: When using these spill-way type filters, make sure that you keep the tank's water level high. A steep waterfall causes vigorous air/water mixing. That like--using air-stones--can easily degas off CO2 and stunt plant growth.


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## mysiak (Jan 17, 2018)

As mentioned in my other thread - I have quite good experience with Aquael filter head with a piece of coarse foam attached on the intake side (to keep shrimp/fish safe) - or one can buy the micro version, which is essentially the same thing. In bigger bowl or classic aquarium it can be attached by suction cups, in small bowl filter just "hangs" in the water by the power cord. Venturi oxygenation attachment is included in the box, so those who need heavy oxygenation don't have to use additional airpump. Price is "ok" - about 20USD, but unfortunately it doesn't seem to be available outside of Europe. The biggest advantage to me is the silence of this solution - I really can't hear it running. I would appreciate even more compact solution though, so looking forward to suggestions/experience of other forum members 

Main disadvantage for "standard" tank is quite small filtration area, but in NPT it doesn't really matter.


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## Octofish (Aug 29, 2018)

Just started using this one: 
Tunze universal mini pump
Smallest submersible I could find. Adjustable flow. Using in a 2.5 gal. Very light flow.

https://www.tunze.com/en.html?user_tunzeprod_pi1[predid]=-infoxunter051


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## zolteeC (Dec 26, 2017)

I have small ~15l NPT that is full of plants and red cherry shrimp. It has been always working very nicely without any filter, heater etc., and I am happy that I do not need any of these stuff. All these cables etc does not look very good in such a small tank.

But the topic is great, filtering and water circulation is always a challenge when one needs it.


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## Octofish (Aug 29, 2018)

I have been under the impression that water circulation was a requirement with the Walstad Method, but looks like I was wrong. Is it safe to assume that it is easier to do without circulation in smaller tanks and bowls? Is water depth a more important factor than volume? Have people had success without circulation in larger deeper aquariums?


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## tiger15 (Apr 9, 2017)

I have two 1g Bowles that are all natural, not even artificial light. They are heavily planted on dirt substrate and receive several hours window sunlight. The strong sunlight drives the self sustaining eco system and generates more than adequate O2 to sustain the shrimp and invert inhabitants.

https://www.aquaticplantcentral.com/forumapc/el-natural/140873-nano-npt-bowl.html


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## mysiak (Jan 17, 2018)

Octofish said:


> I have been under the impression that water circulation was a requirement with the Walstad Method, but looks like I was wrong. Is it safe to assume that it is easier to do without circulation in smaller tanks and bowls? Is water depth a more important factor than volume? Have people had success without circulation in larger deeper aquariums?


I had a 2.5g fish bowl running first without a filter and then with the filter. With the filter I had much more active shrimp and fish, uniform temperature in the tank and I believe that also a better distribution of nutrients and oxygenation of substrate. Currently I'm running the same bowl without any filter, but also with no fish/shrimp and there seems to be a slightly slower growth, though that could be due to many different factors.. 

All in all, I would say that filter is not mandatory, but beneficial, especially in tanks with fish/shrimp.


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## zolteeC (Dec 26, 2017)

Octofish said:


> I have been under the impression that water circulation was a requirement with the Walstad Method, but looks like I was wrong. Is it safe to assume that it is easier to do without circulation in smaller tanks and bowls? Is water depth a more important factor than volume? Have people had success without circulation in larger deeper aquariums?


I have a 200 liter outdoor NPT with no circulation. It is quite lightly stocked with Endler Guppies. I also had a 400 liter tank with very minimal circulation (mainly rainbow fish) . My 15 liter shrimp and endler guppy tank also does not need any water circulation.
I guess one of the main risk is with new tanks with freshly submerged dirt. I have never seen this potential issue with my tanks, I use my yard dirt, maybe that does not have such large O2 demand when it is submerged, or who knows.
Luckily I have never ever seen any fish gulping for air in my tanks, but I have aerators and filters in hand for emergencies (which thankfully has never happened...).

I am curious to hear what you all are doing. Or is my setup too extreme?


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## dwalstad (Apr 14, 2006)

Filtration and water circulation are not the same. And an air-stone loses more CO2 than the straw-like, glass tubes that I use. While water circulation is probably about the same, many tiny small air-bubbles (from air-stone) will do more CO2 degassing than a few large bubbles. Tiny bubbles have more total surface area for gas exchange than the same air volume packaged in big bubbles.

I've now hooked up gentle air bubbling (30-60 big air bubbles per minute) from the cheapest available Whisper Air pump to 4 brine shrimp bottles and 2 tanks. (Plan to use the two remaining outlets available on my gang-valves for a couple more tanks.) 

I described the basic setup at the start of this thread in April 2018. It is working great!


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## zolteeC (Dec 26, 2017)

--lots of guessing here--

I am guessing that too much filtration / circulation may cause issues in the long run for the NPT. In the early phase (first several months, or even longer), soil releases good amount of CO2 to the water column and also it may be rich in *all* nutrients.

As time progresses, the fish food, that contains some C and all other plant nutrients will become a larger factor to feed the plants. _Cleaning_ filters too _frequently_ removes C and some nutrients too quickly from the tank. Strong water circulation also degases the CO2 since _often_ there is considerable more CO2 in a healthy NPT than the air-water equilibrium would suggest. (lots of plants will also remove CO2 relatively quickly when light is on, but this is what we want.)

The question is, what if one has a relatively large filter volume with quite slow water flow? If this filter is cleaned very rarely, I guess CO2 will still be released by microorganisms when water rich in O2 flows through it. Large volume does not necessitate frequent cleaning.

Coming back to my no circulation tanks, has anyone ever experimented fish gulping for air in a mature NPT? Cases where something is obviously wrong, does not count (like fresh submerged soil, or sick fish, very hot temperature, heavy over stocking etc). In my no circulation tanks I have never ever seen fish gulping for air, but they are relatively lightly stocked (lots of shrimps and small fish) and tempearture is around 20-22C.

The thing with air pump is, that I dont really like the noise. (At least the ones I have are not very silent.)


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## Gerald (Mar 24, 2008)

If you want to circulate water with minimal surface disruption (to retain soil-generated CO2) you could add an airlift tube with a vented cap above the water surface and outflow holes below the water surface, like this: (the light blue-green circles are bubbles, not holes)


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## dwalstad (Apr 14, 2006)

zolteeC said:


> Coming back to my no circulation tanks, has anyone ever experimented fish gulping for air in a mature NPT?


Not me!

I have 3 Whisper 10 air pumps. Last one purchased in 2017 cost me $4.19. They are very quiet and I have two that are at least 10 years old.

The rare times that they've made noise, I put the pumps on a styrofoam block or simply bled off extra air power. If you fiddle with them, you can get them to be quiet.


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## Octofish (Aug 29, 2018)

Gerald said:


> If you want to circulate water with minimal surface disruption (to retain soil-generated CO2) you could add an airlift tube with a vented cap above the water surface and outflow holes below the water surface, like this: (the light blue-green circles are bubbles, not holes)


I have been thinking about making a similar device, but the bottom end would be inserted into the substrate. The bottom end would have holes covered with some sort of mesh which would prevent substrate material from entering the tube. Tube(s) could be inserted into deep substrates to prevent anaerobic conditions.


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## Gerald (Mar 24, 2008)

Mike Wise described how Brazilian fish collectors pile up sand or gravel in the corners of their holding tubs, poke an airlift tube into it, and voilà -- a simple bio-filter (for those with access to electricity).


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## Octofish (Aug 29, 2018)

Gerald said:


> Mike Wise described how Brazilian fish collectors pile up sand or gravel in the corners of their holding tubs, poke an airlift tube into it, and voilà -- a simple bio-filter (for those with access to electricity).


Ah, that is interesting. I misunderstood the airlift tube, and did not realize that it works with an air pump.

I wonder if anyone has heard of a non-electric circulation system. Passive solar? Especially in a climate with a lot of sun. Could probably both heat and circulate the water.


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