Xiaomi Mijia 20Ltr Smart Fish Tank Review & Maintenance Guide

662

Having a fish tank can be a tranquil and uplifting experience for both the mind and soul. The gentle, rhythmic movement of fish swimming and the soothing sound of water can create a calming atmosphere, helping to reduce stress and anxiety. Observing the vibrant colors and graceful motions of fish can provide a form of mindfulness, encouraging present-moment awareness and relaxation. Additionally, maintaining a fish tank can instill a sense of responsibility and routine, fostering a deeper connection to the natural world. For many, this peaceful hobby becomes a source of joy and a serene escape from the hustle and bustle of daily life. 

Do you have a fish tank, or are you considering getting one?

-Intro blurb care of Bing Copilot 2025, the rest of the page is written by me a human.

Fish tank 2 year update:

Like the old saying about Chinese products goes... my recommendation for this tank is “poor build qualit" - “avoid and do not buy.”

Reasons for this conclusion are the pump failed after one year, now after two years the heater has died and the display on the tank has faded unevenly and looks terrible, in conjunction with the poor display the temperature sensor no longer displays the correct value as you can see in the picture with a temp probe placed into the feeding hole.

Buttons on top of the tank still work to feed, adjust the light, set pump speed and power on/off. The internal tank light still works well and all smart features are still working via the connected app on my phone. I’ve replaced the heater with a different brand so I will report back if that one dies too.

Also I will mention here that changing the media filter every year, as recommended, is a bad idea because your tank’s nitrogen cycle will be thrown into chaos when most of the good bacteria is removed suddenly. I have updated the section in this article for filters to better recommend an alternative.

24-September-2025 Update(One year):

The pump has died 16 months after purchase, it would appear they know the original pumps fail as there is an updated v2 pump on AliExpress.

Original Article Starts Here:

I’ll start by saying this is the perfect sized fish tank for the lazy hobbyist, this is because of it’s small size at 20-litres and it’s well designed pump with built in syphon as well as the smart auto feeder and auto RGB lights( the lights are so cool it has a colour change setting which I put on so my fish can have a disco). The small capacity of the tank makes maintenance a breeze as you’ll only need half a bucket of water changed each week, I’ll detail proper fish tank care and maintenance later in this article.

The appearance and function of this smart tank is second to none… ignore the fact it’s Chinese technology because we are in 2025 now and the Chinese are at the forefront of tech and great user experience in apps. Speaking of apps, if you’r not in China this tank will not show up in the Mi Home app when it’s set to your proper region, to fix this and see then add the tank change the region in-app to main land china. The time zone will also change to China and this affects feeding and lighting schedules but it’s not hard to work out the time zone difference, mine is 3 hours ahead on the app.

The features of this tank are as impressive as its looks, very clear glass, easy and compact filtration system, heat and pump all hidden at the back of the tank, as well as smart’ features like auto feed and light.

Shown here is the tank with the back cover removed, the base filter on the left, the bio-filter next to the right, the heater then the water pump. You can also see the auto feeder full of food, I use two types of food because one sinks and one floats, the food will need to be small pellets for this feeder to work properly, flakes would get stuck and clog up the outlet… it will not work with flaked food. My Gourami eats all the micro pellets floating on the surface and the Neon Tetras grabs some of the TetraMin food as it sinks to the bottom and then they sneak to the top when they can to grab some floating food when the Gourami is not looking. I have always feed my fish once a day by hand in older tanks and I continued this routine with the Mijia smart feeder for the first year and I had no problems, at the time of writing this article (just yesterday) I have changed to feeding the fish twice a day because the automated feeder mechanism does not release a huge amount of food, even on the ‘full’ setting, there’s also a ‘half’ setting switch. Another reason for the increase in feeding cycles was that I noticed the Gourami(the big fish) was always so hungry when the food came out he would go crazy, I don’t want to starve these fish or make them go hungry, they are my beloved pets after all, so I will see how we go with feeding twice a day and I’ll update this article with the results later. Food Update 26-10-2025 I now feed flakes by hand morning and night and use the auto feeder at lunch time.

Maintenance:

With every fish tank there is a chemical cycle of life in the water. It starts as fresh oxygenated water and then the fish poop and breathe it creates ammonia and uses up more and more of the oxygen over time. To combat this we do weekly one quarter (1/4) water changes and also vacuum the sand every second week(you can push it to 3 weeks if your lazy one month but just like a cat or dog you need to clean up their poop which in fishes case sinks to the bottom.) The tank comes with a hose to syphon straight out of a specially and thoughtfully designed hole in the top of the pump, making water changes as simple as anything.

The good bacteria in the water & bio-filter converts ammonia into nitrites(another chemical) which then, in the working tank; converts into the least harmful and problematic chemical called nitrates. Ideally you want all three of these(ammonia, nitrates and nitrites) to be as low as possible because your fish like ‘clean water with lots of oxygen’ not ‘dirty water with lots of chemicals.’ 

Don’t worry about buying and using expensive water test kits, if you follow this guide created after years of healthy and successful fish keeping you will have no problems, you just need to be consistent, remember your fish need to breath and the only way to get fresh oxygen in… is water changes(or a little aeration from the pumped water dropping down onto the surface, but forget that).

Notes on first setup of your fish tank:

When you open and setup your fish tank the first time or after a filter change you will need to introduce the helper bacteria that does the chemical conversions of water compounds. To do this add 10 drops of Bio Starter(available at pet shops) to the inside rough surface of your Bio-Filter, this surface is porous which means it has lots of holes and a large surface area for the bacteria to live on and in. After adding the Bio-Starter to the filter and placing it back in the tank that is now full of water, leave the pump running for two weeks with no fish in the tank. Repeat adding Bio-Starter after week one to get it topped up really nice and working well.

Here’s a look at the settings in the app and the filter change warning system, you could try and wash these filters instead of changing them every time but I’m yet to test this out, my ones didn’t really get very dirty after the first six months and one year change time came around:

The tank asks you to replace the Biochemical filter every 12 months, this is a bad idea as most of the nitrogen cycle will be disrupted by removing this filter. As I see it you have two alternative options when this filter becomes clogged, which is not always at 12 months. One: keep using the same filter longer than 12 months until it’s totally blocked up. Two: When the time comes to replace it place the new filter into the main section of the tank in conjunction with the old one still in place, this is intended to build the bacteria on the new filter from the old one, I’m unsure how long this process takes but I do know starting a new tank can take 2 months for the bacteria to full establish.

One year bubbler update 26-10-2025:

I’ve discovered a much needed addition to this tank a factory air pump that’s surprisingly quiet! It’s about $20 on Aliexpress.

If your still interested in purchasing this tank, here are some links:

For Australians you can buy this tank and accessories at https://www.pcmarket.com.au/?kw=fish+tank (Not sponsored)

Or purchase on AliExpress for cheaper and get the Chinese version which is exactly the same but with Chinese power cord: grab it here: https://a.aliexpress.com/_mt1l93b

Enjoying our content? Please consider buying us a coffee here : https://ko-fi.com/naturalwayonline