Introduction: Pico Aquarium in a Mason Jar (almost Maintenance-free)

Picture of Pico Aquarium in a Mason Jar (almost Maintenance-free)


today I noticed the "mason jar contest" and thought it would be the right time to finally publish an Instructable for my "pico aquariums". I´ve been experimenting on those for some time now (years to be exact) and always thought to myself; "Damn, this works so well and is so simple, you have to make an `ible for this, parents and kids will love it...".

So here it is,

The guide to an (almost) maintenance free Pico-Aquarium in a mason jar with living plants and snails

  • Cheap
  • Easy to set up
  • Decorative
  • Closed, almost self-sustaining micro-ecosystem
  • Not hermetically sealed, you can still intervene at any time
  • Plants and snails can survive weeks, even month without any intervention
  • Suitable for kids in preschool age
  • Portable

Step 1: How It Works (simple Version)

This setup represents a really small closed and self-sustaining eco-system. All it needs from outside the jar is a little energy input (light) to keep it up and running (or better: metabolizing).

The plants (and algae) in the jar produce oxygen via photosynthesis if exposed to light. The snails breathe in this oxygen and breathe out carbon dioxide and nitrogen, which the plants need. The snails also eat tiniest and almost invisible algae growing on the plants and on the inside of the jar and keep it it clean. Their leftovers (snail poop) are then metabolized by micro-organisms, whose leftovers are the nutrients which the plants and algae need to survive and grow.

Sounds simple, but in reality it´s a little more complex:

But as opposed to classic "open" aquariums, all the gases and microbial metabolic products stay inside the closed containment and are reused/recycled/re-metabolized. The food for the snails is not regularly added from outside, but grows in the containment, maybe you might need to feed a tiny amount once in a while to keep them growing.


Important: It seems like a few people only read the topic and are concerned about the well-being of the snails in a closed containment.

  • This is not an hermetically sealed environment like the so-called "ecospheres" or alike.
  • You can always open it, feed the snails and/or change water if necessary.
  • Don´t put the jar in a place with direct sunlight! A bright place is fine, but direct sun might kill the snails, they will get literally boiled while your away and you won´t notice.
  • You have to take care of it, but a lot less frequently as compared to classic aquariums, plants or other pets.
  • The recommended plants and snails are very undemanding and able to 'survive' weeks or month without intervention, once a balance is established. They can live, settle and breed in much harsher environments.
    But if you care for them, they will surely do a lot better!
  • The closed lid is intended to prevent evaporation of the water in such a small containment. If you prefer to leave it open, you will have to change water regularly (e.g. almost daily), not only fill up evaporated water, or things might get out of control.
  • I recommend to keep the lid closed most of the time and only open it to feed tiny(!) amounts, or change water if necessary. (In the start-up phase and until you observe recognizable algae growth, or if regarded as necessary afterwards).
  • If you still fear to suffocate the snails, you might consider to punch a hole into the lid, but still keep it closed. Unnecessary, as long as you keep living plants in the containment which regularly get some light, the snails will do fine. Not recommended, but optional.

Step 2: Materials and Tools

Picture of Materials and Tools

What you need:

Hint: If you got a friend or colleague with an aquarium / fishtank, tell him/her about your project and ask him/her if he/she can provide you some samples/supplies. Easiest and safest way and most of the aquarists will be more than happy to give away some excess "material" and good advices for free.

  • Mason jar(s) with an airtight lid (0.25 to 0.5 litres worked fine for me, less can get a little complicated, the bigger the more uncomplicated to maintain)
  • Soil:
    I used natural black sand (not artificially coloured) from an aquarium store (see picture). Not the cheapest solution, but all natural and not spray painted like the cheap alternatives. You should wonder if it says "Do not rinse in hot water" on the label.
    You can use "normal" sand or gravel as well, just make sure you rinse it thoroughly several times until the water water you drain after rinsing is really clear.
  • Small aquatic plant(s):
    Tiny cuttings/offshoots of "anubia barteri var. nana" worked best for me. These plants are very sturdy, slow growing and if kept in a small containment without an excess of nutrients, they keep forming many small leaves instead of fewer big leaves, which is undesireable in this special case. Some strains of "java moss" (vesicularia dubyana) works fine as background accent. But these are only recommendations, feel free to experiment on your own with different plants, but I recommend using slow growing species
  • Snails:
    Your pico-aquarium can work without them for a while (plants only), but if placed in daylight you will notice it will clog up with algae at some point. Suitable for living in such a small space are ramshorn snails (Planorbarius corneus) and/or bladder snails (Physella acuta). Add max. 2 ramshorn snails per 0.25 litres of your containment, or 3-4 bladder snails.

  • Stones (optional):
    For decoration and scaping a miniature landscape in your jar. I used small pieces of slate which corresponds to the colour of the soil I used. You can use other stones as well, but I recommend slate, lava rocks or flint, which almost don´t react to the surrounding water, don´t use limestone or sandstone.

  • Last but not least, water:
    Seems quite obvious and simple, BUT;
    I recommend using water taken from an aquarium with healthy plants and fish in it, which was set up at least several month, if not years ago. Ask a friend maybe.
    This water contains all the micro-fauna (bacteria) and micro-flora (algae) which is needed to get the metabolization and food growth processes in your (tiny) containment started.
    Tap-water might or might not work. Make sure it´s free of chlorine and copper (most older boilers use copper pipes, so if you use preheated water from your tap it might be deadly for the snails), open tap and let the COLD water run a while, after that fill a containment with water and let it sit for a while until it is about at room temperature before you use it).


  • a little spoon to fill in the soil
  • long tweezers and/or chopsticks come in handy to arrange plants and decoration (not shown)

Step 3: Add Soil

Picture of Add Soil

Step 4: Add a Little Water to Let the Soil Settle

Picture of Add a Little Water to Let the Soil Settle

Add some water and sway the jar a little until the soil is spread out evenly.

Step 5: Add the Plants

Picture of Add the Plants

If the soil is soaked and evenly spread out, add the plants. Optionally use stones to keep them in place.

If you use Anubias be sure to not bury the rhizome (the "stem") in the soil, as it will rot. Place the rhizome above the soil and the roots will grow into the soil.

Step 6: Carefully Add Some More Water

Picture of Carefully Add Some More Water

Step 7: Time to Introduce the Inhabitants to Their New Home

Picture of Time to Introduce the Inhabitants to Their New Home

Put the snails in. Check back for Step 2 for the recommended number of animals regarding the volume of your containment.
Don´t add more than recommended, as the snails will starve. Don´t add less, as your "aquarium" will get clogged up with algae in short time.

Step 8: Almost Done

Picture of Almost Done

Fill up the jar with water to max. 1 cm below the rim. Put on the lid.

Don´t worry about bubbles or dull water, it needs some time to settle and will clear up by itself.

Note: Do NOT fill the jar up to the rim with water and leave some space for air! The snails I recommended have lungs, not gills. They can breathe submerged though, but they need to fill up their bladder with air to be able to gain oxygen from the water. Otherwise they will drown (sort of).

Step 9: Done

Picture of Done


welcome to the world of aquarists ;)

A few notes for you:

  • "Almost" maintenance-free doesn´t mean you don´t have to care. These containers and its dwellers can survive weeks to month without interference, but having a look at them once in a while won´t hurt either you or the inhabitants. Check regularly if plants and snails are doing good, open the lid and have a smell. If it stinks, something is going wrong and you need to change water and/or rebalance the plant/animal ratio.
  • Don´t put the jar in a place with direct sunlight! A bright place is fine, but direct sun might kill the snails, they will get literally boiled while your away and you won´t notice. The snails I recommended feel comfortable in an environment of about 5 to 25 °C. So they don´t need an additional heater, but they also don´t like to get boiled.
  • Don´t fill the jar up to the rim with water and leave some space for air! The snails I recommended
    have lungs, not gills. They can breathe submerged though, but they need to fill up their bladder with air to be able to gain oxygen from the water. Otherwise they will drown (sort of).

  • Normally the snails don´t need extra food. They do fine eating what grows inside the jar, which also keeps it clean. If you experience them to chew on healthy plant leaves and don´t see any algae in the containment, you might consider feeding them.
    But carefully and in really tiny amounts (few flakes of fish food once per week or so). Otherwhise you provide algae and bacteria growth and probably end up with a little jar of stinking green mess.

If you experience any other problems feel free to leave a comment or PM me.

Have fun!


SushantK26 (author)2017-04-05

hi, I just made pico aquarium , thanks for instructions ! As you can see I made one and add some laterite stone and ADA subtract and some plants like Weeping moss
 Cryptocoryne axelrodi
Christmas moss and drift wood stone. Yet i can see some white fog/ cloude layer in water. What is that is it normal? When shud I add snails and shrimps.

confu made it! (author)SushantK262017-04-07

Hey SushantK26,

pretty nice tank you got there :) Really like it!

Few questions first;
How long ago did you set it up? Did you buy the plants as new or took them from an up and running aquarium? Did you use tap water or water from a running aquarium (at least in parts)? Do you have experience with regular (bigger) aquariums?

To answer your questions:
In general it is pretty normal that the water of a newly set up tank gets a little foggy or bubbly in the first days, that will settle by itself.

Since you are planning to add snails AND shrimps, I strongly recommend to treat your tank like a 'regular' fresh water aquarium and follow all recommendations you can find online regarding setting up a (shrimp) tank and when to add the first inhabitants.
A "mostly plants and few snails only" tank is a lot easier to maintain, just follow intructions in the ´ible.

In your case (plants, snails and shrimps) I recommend to let it run for at least one week (min.) with plants only and after that add snails, let it run for another two weeks (min.) and add shrimps after that period and only if everything seems ok. Buy some test-stripes for regularly checking water quality.

Regularly feed the inhabitants in tiny amounts (shrimps might not be able to survive on naturally growing algae only, especially if the tank has not established a natural balance yet). If the 'tank' gets too green, stop feeding until it´s almost clear again, but observe if it´s dwellers are doing well.

Optional, but recommended in your case; add a small pump / filter to it*.
Your setup "as is" might work without a pump/filter, but would require close observation and possibly regular water changes/maintenance.

I can definetely recommend EHEIM "Mini-Up" or "Mini-Flat" for really small tanks, but those are not the cheapest solution and might seem too bulky for your setup (but will last a life-time).

Attached some photos of my tiny square tanks (max. 8 liters, 20x20x20 cm), left one is powered by Mini-Flat (hidden) (plants and tiny amphibic snails only [aka bladder snails]), right by Mini-Up (hidden) (plants, ramshorn snails and "amano" shrimps).



*Check the net for tiny water pumps / filters. There are several and cheap solutions out there, even tiniest USB-powered pumps. You might have to improvise a proper filtering section for those. I did not test those, so I can give you no direct recommendation.
SushantK26 (author)confu2017-04-08

Hey confu.
Thank you so much looking after my question
No i dont have any experience in bigger aquarium. Im doing it first time so.
I add half river water for growth of alge and half RO & UV water . I setup my tank on 1 April 2017
Cryptocoryne axelrodi i bought it from aquarium store which new and Weeping moss and Christmas moss i took from my friends running aquarium.

Thank you
Sushant K

Fish-A-Majig (author)2016-10-30

My snails are active, but I'm noticing that their shells are getting spotty. Should I add anything to the water to help them with shell growth?

confu (author)Fish-A-Majig2016-11-04

Are you keeping more snails than recommended (my first guess)? Do you feed them? How long since you set up the "tank"? Are your plants doing fine? Does the "tank" get enough daylight for algae to grow for the snails to feed on?

Snails tend to nibble on each others shells if there are too much in one containment and/or they don´t find enough lime sources for shell growth in their food and environment. Or they find too less food at all. That may cause the spotty shells.
The snails will do fine even with spotted shells, but it is an indicator of a lack of something.
Note that the spots won´t go away once they are there, but new grown shell areas should stay free of spots if you try solutions beneath.

Possible solutions:

- Reduce snail population.
- Add a small limestone or a seashell as a lime source.
- Feed tiny(!) amounts until you notice (slightly) visible algae growth in the containment. Like a slight green haze on the glass walls and on the plants.
Try little pieces of salad leaves or cucumber, but observe closely, those must be completely eaten up after max. 3 days, otherwise remove leftovers as they will rot. You might as well use regular fishfood, just make sure it´s eaten up within a few hours. Once algae growth has been established you can see the traces which the snails have grazed if you take a closer look. Stop supplemental feeding then.
- If the water "stinks" noticeably, do a 2/3 water exchange on a daily basis until it doesn´t stink anymore and smells like water from a pond or doesn´t smell at all.

Let me know if that helps ;)

poiuy22 made it! (author)2016-01-31

hey bud, I just finished them, thanks a bunch for this instructable! As you can see I made 2 of them and then I made a breeding jar with 2 of the snails left :)

Hehehehe (author)2015-07-22

the plant could die from lacking of nutrients if you use only sand , sand don't have nutrients , i suggest you should using some aqua soil or some dirt . oh , and just a reminder ramshorn snail breeds quickly so i suggst u guys just use horned snail (cause they qre brackish watered snail , so they don't breed on freshwater ) . sorry if my words isn't really polite

molassesfats (author)2015-01-21

has anybody had luck with tapwater? can you just ask a aquarium supply store for a cup of their water from some ecosystem of theirs? i don't have access to any pre-established aquariums.

What you can do is go to a pet store and buy some water treatment stuff (I think petco carries it in the beta section)

Akin Yildiz (author)2015-01-16

well, we both made it so far :)

confu (author)Akin Yildiz2015-01-16

Yeah, I was really surprised to get that far. Pretty cool :)
But it´s "indoor gardening", indeed. No matter if the plants life above or below the water surface. Living below makes things easier in some special cases, for example it´s pretty easy to tell if the plant needs water ;D
Good luck! CU around:)

thechocolatist (author)2015-01-09

Great idea!! Thanks for the inspiration!!

confu (author)thechocolatist2015-01-16

Thanks in return, just watched your biosphere Instructable. I have some large glass spheres from a seventies lamp stored in the basement, will definetely try to build a biosphere with emergent plants in them, although I´m more into those submersed things ;)

Beste Grüße in die Schweiz

MaartenD (author)2014-12-16

How long will they survive?

confu (author)MaartenD2014-12-29

See answer to jscheckel on the intro page.

Mondomonkey (author)2014-12-23

This is a really cool idea, and I think when I have some money I will try it out :D

confu (author)Mondomonkey2014-12-29

But best idea is still to ask around if a friend or workmate owns a fishtank and might provide you some samples for free, rather than buying everything from a pet store.

jscheckel made it! (author)2014-12-23

I made two of of these, one for me, and one for a friend for Christmas. She loves it and I do too. Mine are a bit bigger and seem a bit more crowded, in addition to the plant, I have about a third of a moss ball in the jar. What signs should I tell her to look for to keep everything alive?
Great Instructable. Thank you so much.

confu (author)jscheckel2014-12-23

Thanks in return!
Hope you like it. :)
From my experience you don´t really have to do anything, as long as the plant or plants look healthy and get enough light.
Ramshorn or bladder snails can get max. 2-3 years old, makes no difference if kept in a community basin or in a jar.

Otherwise you can tell by smell... Open the jar once per week (or every two weeks if it seems to be stable). If it stinks, somethings wrong. Change water 2/3, and 2/3 next day and keep observing.

A dead and rotting leave is a fest for the snails, so don´t instantly remove it.

If the snails start chewing on obviously intact leaves, you probably need to feed them.
Few(!) flakes of fish-food will do, or tiny(!) portions of cucumber shell (snails LOVE cucumber) or a scrab of salad will do. But remove leftovers which are not eaten within 3 days.

But I think problems will more likely occur by supplementary feeding, rather then leaving it untouched.

chanchala.singh.58 (author)2014-12-20

wow...thats so lovely....i would love to watch cute snails in anger to calm me down....lovely....

confu (author)chanchala.singh.582014-12-21

Assume you didn´t read all steps carefully, especially the 'important notes' in the last step?!
But to prevent comments like this, I changed the intro and added a "disclaimer" and important advices right to Step 1.

Check back, if you like.

chanchala.singh.58 (author)confu2014-12-21

i think u didn't get me i want to say these are so cute that they can elevate your mood by only looking at it....

confu (author)chanchala.singh.582014-12-22

Oh, please excuse my misunderstanding!! I read it as if the snails were in anger... ;D
I´m really sorry!
So here´s something for you to calm you down hopefully :)

reedgleason (author)2014-12-16

A stereozoom microscope is really good here.

I used to do this by scooping up a jar of pond water, putting a lid on it, and setting it in a window. There were some hydras on the glass walls. I wish I had a jar with better optical properties.

MINECRAFTfern (author)2014-12-15

Don't have any fish ponds,lakes,or streams close to my area. I live in Buckley WA any store ideas or websites that would sell bladder, or ramshorn snails?

We're in Edmonds, WA and definitely can help you with any snails you may need.

confu (author)MINECRAFTfern2014-12-15

Don´t know how it works in the US, but here in Germany we have several online stores where you can mail-order aquatic invertebrates and plants.
Quick googling for you:
check this... just an example, think you will find more.

cory.mcelroy.37 (author)confu2014-12-16

Yes we definitely do ship out inverts and fish all around the country :)

hsteinbe (author)2014-12-16

For the base use 1/3 generic cat litter (kaolin clay with no perfumes or additives) and 2/3 sand. Over time this base layer will seal (with algae and bacteria) and go anaerobic. This will help with your nutrient cycling because there are some beneficial nitrifying bacteria that can only live without oxygen. It also helps to add pond water or aquarium water to get all the beneficial microbes at the beginning.

For the lid use a regular mason screw ring on a regular mason jar but replace the metal lid with a round glass or plexiglass disk to let more light in. You can seal it with rubber ring from the hardware store, or one you cut from a truck inner tube, or a seal from a resealable mason lid.

xenobiologista (author)hsteinbe2014-12-16

Really interesting tip on creating space for anaerobes.

dkistner (author)2014-12-16

Assuming you follow the recommendations for number of snails to liters of water, what is the largest jar you could use for one of these habitats?

confu (author)dkistner2014-12-16

I mostly used containments of about 0.25 to 0.75 litres. Those worked fine with the recommended snail/volume ratio. Wouldn´t recommend anything smaller, the picture of the really tiny jar was just for demonstration and didn´t contain snails, only plants.
If you want to go bigger than 1 litre I would suggest to add an active filter and treat it like a nano aquarium, e.g. not completely closed and regular feeding in tiny amounts.
But see fixfireleos´ comment, think he pinpointed it.

dkistner (author)confu2014-12-16

Thanks, guys!

fixfireleo (author)dkistner2014-12-16

the more snails you have, the MORE snails you have. seems they would overwhelm the environment quickly.

jlathem56 (author)2014-12-15

The objective is to get a balance. Also there was nothing suggested about using shrimp. She did suggest leaving a space at the top that will give the snail a place to get air.

Any aquarium can be over stocked and fall into the conditions you described but this is not what se suggested.

DragonTamer458 (author)jlathem562014-12-16

The ones I've seen elsewhere online have used snails. But that's not the point. Nothing is adapted to ecosystems this small. The smaller an ecosystem is, the harder it is for it to balance. Pico tanks very rarely last longer than a few months. In this setup even the plant won't last long. The snails don't respirate enough to create that much CO2, and there isn't enough nutrients to sustain it. If you left the top off and fertilized it then it could work, but in the manner described above, you're just killing everything.

confu (author)DragonTamer4582014-12-16

I´m also pretty sceptical about those shrimp tanks sold online, aka "ecospheres"->

But in contrast, these "tanks" contain living plants and are closed, but not hermetically sealed, so you can intervene if something is going wrong.
You have to care of them just as for all other living things you keep, but not that frequently.
I set up over 25 of these in the last 5 years and I can definetely tell that it works and neither the snails nor the plants suffer or die prematurely, otherwise I wouldn´t have made an Instructable for it.

I had the idea when I put some anubias offcuts in a closed mason jar to replant them later, forgot about and rediscovered them over a year later. Against all my expectations they were doing fine, as well as a few snails which were sitting on them. The jar contained algae, but was not completely clogged up. From that point I systematically experimented on that subject to find the right balance of plants and snails.

If you use an open container in this size as you suggested, it is almost impossible to keep the conditions stable. Water evaporates quickly and the dissolved salts stay in your container and so you have to change water regularly.

The respiration of the snails seems to be quite insignificant for the plants. Without additional CO2 and fertilizer they simply grow slower and smaller (which is intended), but do not "starve" or even die.
Give it a try and report your results.

Seven Voices (author)2014-12-16

This sounds like a cute idea for a school experiment too. :) It can teach a lot about habitats, taking care and about how important it is to treat nature with respect. :)
I don't have kids, but I am sure, that my nieces and nephews would love this project.

confu (author)Seven Voices2014-12-16

Give it a try and report back :)
That was my intention, I thought it´s fun, pretty simple to set up and maintain for preschool kids and up, but still needs some degree of attention and responsibility.

DaveF2 (author)2014-12-16

I have an office without windows but I do have florescent lights. I've noticed that some lower-light plants will grow just fine in only florescent lighting. What are your thoughts for putting one of these in my window-less office?

confu (author)DaveF22014-12-16

Hmm, dunno, but I think you can give it a try. Anubias surely are "lower-light plants", if they get 7-8 h of artificial light per day, they should do fine, but won´t grow "fast".
Problem could be insufficient light for algae to grow, so you might need to feed the snails from time to time. Snails love cucumbers btw. so you can feed a tiny slice every week, but be sure to have an eye on it and remove the leftovers which are not eaten within 2-4 days.

If you feed to much, you will have 33 instead of 3 snails in a much too small containment within no time...

sharpstick (author)2014-12-16

I've made these with amphipods, small crustaceans(about 1/8" long) that live in ponds and ditches just about everywhere. I've done this in as little as a quart jar. They stabilized and lived for several years without opening it.

MINECRAFTfern (author)2014-12-15

Do you have to use bladder/ramshorn snails or can you use any feeder snail?

Akin Yildiz (author)2014-12-15

cool stuff, you should enter it to indoor gardening contest.

confu (author)Akin Yildiz2014-12-15

Just entered. But I think you should get the prize and voted :)

mourmoura (author)2014-12-15

hi, great tutorial. You know there is also an open contest about indoor gardening, maybe consider entering that one too?

confu (author)mourmoura2014-12-15

Done, thanks for the hint :) Please vote ;)

Hasantha2003 (author)2014-12-15

cool, awesome, I am definitely gonna try this, also are you sure the snails to need air to breath?

confu (author)Hasantha20032014-12-15

They definetely do, as they have lungs, though they can breathe submerged in water with them. See my reply to ashleyjlong below for details.

jlathem56 (author)2014-12-14

Have had aquariums most of my life. From 2 gallons to 260n fresh, brackish, & saltwater, I loved them all. I think I will try this one.

Do you know if there are any kind of LED system that will work as an energy source?

About This Instructable




Bio: I like to make / fix / improve "things"...
More by confu:Custom Size/Surface, Ultra-Thin, Non-Slip Mousepad (Gaming/DTP/CAD)Protective cover for spiral book (or any other book) from amazon packaging (free, 10 min.)Work Light / Flood Light meets Camera Tripod
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