12L (3ish Gallon) Tank Ideas


New Member
Sep 20, 2020
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Pacific Northwest, US
This is so exciting! I have a 3.6 gallon tank with a tiny heater and a small filter. I am putting driftwood, sand, and plants in. Currently planting it up and letting it get balanced. It has a couple baby guppies in it right now, one cherry shrimp and a nerite snail. I want to make sure I can get the parameters stable and right and then I was considering a pea puffer.
I was just wondering, the filter is internal and sucks water through a sponge. Is a sponge enough for the bacterial or should I see if I can also put some filter media in there as well, maybe inside the sponge?
I have a small 2.5 gallon tank that I throw any snails I find in my tanks into. How much should I feed him of these small snails?
I do 50 percent water changes every week since its such a small tank. Would this be ok for a puffer? or do they need 2 weekly smaller changes?
Congratulations! Pea puffers are awesome!

My three gallon tank is 18" long, which allows him to "investigate" all the nooks and crannies. I have a small internal filter (Aqueon 3) and a sponge filter (Hygger Super Mini) to have air bubbles and a breeding bed for the ostracoda. If you just have a sponge filter, that should be enough for bacteria and always wash it with aquarium water. Bacteria will live in every surface of the tank.

I do two 50% water changes a week. I took the Mystery snail out due to the bioload, but left the two CRS in. I feed Nicodemus two to four snails a day, stopping when his belly looks full. He eats ostracoda throughout the day. Bloodworms every other day (one or two).


Fish Fanatic
Sep 2, 2020
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I am preparing a 3 gal. planted tank for a pea puffer (single) and in the meantime have a mystery snail, a colony of bladder snails (to be fed to the puffer) and two cherry shrimp. Doing water changes twice a week and running an internal filter and a small sponge filter. I was told if I keep up with the cleaning, it should be ok for the little pea puffer.
It has been cycled, params:
Nitrate: 0
Nitrite: 0
Ammonia: 0
PH: 6.8

View attachment 117117
my goodness this tank looks very nice!


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