Planted Aquarium Expert

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snail on top of aquarium plants

Image above is of my 2.9 gallon nano aquarium. A snail and plant pearling. 

First, How large is your aquarium and is it a nano? What is old food?


What is old food? For the sake of this article, I will consider old food to be uneaten food that has been decomposing in your aquarium for a while.


What’s a nano aquarium? We need to know what a nano aquarium is, because the environments of nano aquariums change rapidly if there is a problem (like old food lying around decomposing). 


A 2.9-gallon aquarium that I have is definitely a nano aquarium. I also have a 10 gallon tank that was set up as a nano aquarium. I’m not sure a 10-gallon tank is a “nano,” so, for the sake of this article, I will say any aquarium that is too small to have fish living in it would be a nano. 


The smallest nano tank I’ve found was a 1.6-gallon aquarium. It is so cute! You can see it here on Amazon.

Second, why is old food that is left in a nano aquarium a problem and what is an ammonia spike?

Nano or small aquariums are physically super-easy to work on, but…

Nano’s might be easy to work on, but the big issue is that the environments are delicate, and prone to rapid change because the tank is so small. A small action on your part (overfeeding) can lead quickly to extensive problems. The worst problem is ammonia poisoning of the animals.

Decomposing matter produces ammonia as it breaks down. Old food left in the aquarium produces ammonia. Ammonia is a very concerning chemical to have in your aquarium because it quickly kills aquarium animals. Sometimes even before you’ve noticed something is wrong.


Because of ammonia spikes, having leftover food in your nano aquarium is like playing with fire. 

You can get information about removing ammonia in your aquarium, naturally, by reading this article I wrote. 

Overfeeding animals in a nano aquarium seems unusual to me. Begging fish is the usual cause of overfeeding. If this is the case, what are fish doing in your tiny aquarium? 

As a caring, careful aquarist, I can’t imagine putting fish of any kind in a small nano (less than five gallons). The aquariums are just too small. This leaves snails and the smaller freshwater shrimp species as nano aquarium inhabitants. 

I feed my snails daily, as you can see in this picture. My snails are eating bloodworms: 

Nano aquarium snails Pink ramshorn snails

The snails and shrimp work on eating the algae but algae isn’t enough “food” for your animals. Hence, they have to be fed. Or with this article, unfortunately, overfed.

Awesome National Geographic freshwater shrimp video:


Bristlenose / bushynose plecostomus catfish

albino bristlenose pleco

Third, It would be good to know what type of aquarium system you’re running


Before I discuss cleaning up old food in a nano aquarium, I need to discuss what type of aquarium management you’re using to care for your nano. Why is this important? This helps me to recommend the actions you will need to take to get rid of the old food in your aquarium. 

From my perspective, there are two types of care systems for nanos, open care systems and closed care systems. 

An open care system is a system where the owner cleans the system fairly frequently. The aquarist using an open care system cleans the gravel, changes the water, trims the plants, and often adds liquid plant nutrients to the nano.

A heavily planted, closed care system is a system that is rarely, if ever, cleaned. The animals in a closed system are fed daily. This feeds the plants at the same time. This type of aquarium management was discussed in the book by Diana Walstad, “Ecology of the Planted Aquarium.” (affiliate link)

To give you a non-nano example of a closed system, I have a 30 gallon that I haven’t cleaned in a couple of years, except for the trimming and removal of plants. Here is a video of that aquarium that I took today.

The plants are healthy; the fish are healthy, and I have a beautiful aquarium that requires very little care or time. Maintenance of this aquarium requires that I take out about a gallon of tank water each week to water my house plants. I replace that water and water lost through evaporation by topping off the tank with purified, reverse osmosis water. I also occasionally trim the plants and throw the trimmed material away. 

Managing a closed system in your nano tank means, mostly, you don’t really care about occasional overfeeding.

Managing an open system means worrying more about issues that might come up in your nano aquarium, including occasionally overfeeding. If it’s more than occasional, you probably need to get more experience as a hobbyist. 

I’m going to assume for the sake of the rest of this article, that you’re using an open nano aquarium system. I’m also going to imagine that you have a fish or two in your little tank. If you have fish in your nano aquarium, bad aquarist! Go stand in the corner and think about what you’ve done. Don’t put fish in a nano (five gallons or fewer) aquarium! That’s just cruel. 

Ok, so I’m a little opinionated, but base my opinions on decades of aquarium care and experience.

Fourth, how to clean out old food from your nano aquarium

1.  Use Cleaning Animals – Shrimp and snails. As an FYI, if you don’t have either of these animals in your aquarium, it’s time to buy some. For snails, I recommend ramshorn snails. They love algae and they are the right size for a tiny aquarium. They’ll clean up old food and keep algae growth down.

Shrimp are the other choice. If you’ve ever seen a video of freshwater shrimp in an aquarium, you will have noticed that they are constantly cleaning up and eating debris. You can see a good video of this here.

With these animals in your tank, you can say goodbye to old food in your nano. 

I wrote an article about shrimp (with tons of pictures) which you can read here.

2.  Use a net – Swish your net sound in a figure eight. This action will pull the food off of the bottom and most of it should end up in your net.


3.  Use a turkey baster – When I used to clean my tanks fanatically, I used what I would call a turkey baster. To use it, you squeeze the bulb and then put the tip of the baster in your aquarium where the food is. Gently and slowly release the bulb. This will suck up the food (and some water) into the baster. Dispose of the water and food mix. Continue to suck out food until you’re satisfied with the job you’ve done. 

4.  Use filters and filtration devices – Using an aquarium filter is more of a passive action than an active one, but it will help. You should use one of these for your nano tank before there is even a problem. It will take up flake food even as you’re (over)feeding your snails or shrimp. Depending on your setup, you can get rid of old food by either cleaning out the filter at least monthly or if you’re me with a close system, maybe once a year.


5.  Stop feeding flake food to your aquarium animals – It is super-easy to overfeed your animals when using flake food. Instead, use sinking foods like pellets and wafers. Another good way to go is to feed them homemade fish food. You can find a ton of recipes for homemade fish food online by doing a simple search.

By eating sinking foods, snails or shrimp will hopefully have a better chance of getting all the food, rather than letting it go to waste with the flakes hiding in cracks and crevices. 

6.  Last, but certainly not least: Stop Overfeeding Your Aquarium Animals. – I think we all are guilty of this. I’ve taken a few actions to help me limit the amount of food I feed my animals.

*    Feeding Change #1:   Take the normal amount of food, put half the food back and then feed the aquarium animals.

*    Feeding Change #2:   Feed your animals every other day (which includes fish in the larger aquariums) just once in the morning. The other days feed normally.

*    Feeding Change #3:   Let your aquarium animals fast for one full 24-hour period. They should use up all the uneaten food that day. This is also good for clearing out their digestive tract.

Zebra Danio / Zebrafish in my planted aquarium

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millipede insects and a silver fork on a white background

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