How to clean and maintain your fish tank. Jenni’s aquarium #3

Keep your fish happy and healthy by cleaning your fish tank on a regular basis. Cleaning your fish tank doesn’t have to be difficult and once you get into a routine, it won’t take you long at all. Swell content writer, Jenni, recently set up her own aquarium, here she writes about test kits, water changes and general aquarium maintenance. 

Testing water in the fish tank

I’ve had my fish tank for over a month now and after spending the first fortnight testing the water with test sticks, I decided to try something a little bit more elaborate like the API Master Test Kit. I opened the box thinking it might be quite complicated to do, but was surprised to discover that it was quick and easy to use!


Let’s just say you don’t exactly have to be Walter White to use this kit as it’s very straightforward. The instructions are helpful and tell you how many drops of each solution to add to each test tube.

  • Fill each tube up to the 5ml line with water from your aquarium
  • Add the designated number of drops of the appropriate solution to the test tube.
  • Add the cap and shake for the amount of time specified on the packet. As soon as you add the solution to the tube the water changes colour, but you’re encouraged to shake the tube for a while as the colour may change again.
  • After 5 minutes you can compare the colour of the liquid in each tube with the chart included in the packet and you’re then given an accurate indication as to the quality of your water.

I was surprised by the results, they were a lot worse than I thought they’d be. Before the test I thought that the 20% water changes I’d been conducting 3 times a week had been doing their job. You might shake your heads and disapprove, but I decided to skip the fishless cycle and added my first fish to the tank after a week. When adding fish to an aquarium for the first time, there is an ammonia spike which is caused by leftover food and waste from the fish. This can be harmful for the fish as they are then swimming in their own waste, which is why it is important to conduct regular water changes and keep your tank clean and avoid overfeeding.

In a fishless cycle, there is no need to add food and the fish are not around to produce waste, so you need to buy a bottle of ammonia to add to the tank which will turn into nitrite and then nitrate. A series of ammonia spikes will occur before the water gradually levels off and you are left with an aquarium that is safe and ready for your fish. Fishless cycles are becoming increasingly popular among aquarists but many still swear by traditional cycling methods and add hardy fish at the start who are able to take rising ammonia levels in their stride.

As you can see in the image below, the pH levels in my fish tank are at 6.0. Ammonia is between 0.50ppm and 1.0ppm. Nitrite is at 1.0ppm and Nitrate is about 10ppm.


At this stage however, the results should be quite different! The recommended pH level all depends on the type of fish that you keep – cherry barbs for example benefit from a pH of  between 6.0-7.0. Ammonia and nitrite should be much lower than the test results show, so it was important to act fast!

Aquarium Maintenance

Here are a few things you can do if ammonia is a problem in your aquarium.

  1. Clean gravel. Use a good gravel cleaner to clean the substrate and remove any leftover bits of food and waste.
  2. Water change. A good 30% water change. Before adding the tap water to the aquarium it’s important to add some dechlorinator to make it safe.
  3. Treatments and additives.  These can come in handy to improve the water quality.
  4. Don’t overfeed. In fact, give your fish a few days off from food altogether to give the water chance to settle. Once it has settled, avoid feeding your fish so frequently.

I know about the dangers of overfeeding but even so, it’s so easy to overfeed your fish without even realising it.

As Swell advisor Chris Plumb says: “For every 1000 people who have an aquarium, around 950 overfeed their fish and 50 people don’t.”

While these numbers are a bit of a guess, it’s surprising just how many people put a few more flakes than is necessary in their tank at feeding time, and clearly I’ve been doing the same!

When I first bought the cherry barbs, I didn’t feed them for the first day and a half. When I did start to feed them, they never seemed particularly interested in the food for the first few times. After a few days though they began to show a bit more interest, trying to break up each flake for a few moments before giving up and looking elsewhere for smaller pieces. So I started breaking the food into much smaller flakes myself to make it easier for them to consume. Still though, there’d be leftovers sat on the substrate for hours until the flakes would eventually disappear. I told myself this was because the fish probably got hungry again, but in reality the leftovers probably had just dissolved and polluted the tank. Due to the levels of ammonia in my fish tank, I decided to avoid feeding the cherry barbs for a few days. Don’t worry! Fish are unlikely to starve. Poor water quality is much more harmful for fish than a lack of food. Poor water quality can increase the risk of sickness and disease and it is far more likely to kill off your fish than hunger is.  

Clean gravel

I used a gravel cleaner to suck out all the little bits of rubbish from the bottom of the tank. Since I mostly use sand as a substrate, I initially thought that the gravel cleaner would suck up all the sand along with the water, but thankfully this wasn’t the case. The gravel cleaner was really easy to use. I just had to place one end in the tank, pressing it against the sand, while squeezing the pump on the other end. It didn’t need plugging in, so it is useful if you worry about getting a shock from the combination of water and electricity.


It’s much easier if you remove the plants and decor from your fish tank first! Although you luckily don’t have to remove the fish – they’ll more than happily move our of your way and won’t get sucked up through the gravel cleaner.


Filter media

It is also definitely worth cleaning your filter media and giving your filter a rinse (make sure you don’t get the plug wet!) Your filter media should NOT under any circumstances be washed under tap water. Instead, use the water that you’ve just removed from your aquarium using your gravel cleaner to soak them before taking a little more water out of the aquarium to give each type of filter media a rinse. As you can see in the picture below, my filter media was absolutely filthy! This is after just two and a half weeks. The sponge in particular had come out the worst – it was white to begin with!


Once I’d cleaned the filter media, I placed it back into the filter and refilled it up with water from the tank before plugging it in again. I then began to add my plants and decor back into the aquarium. One problem I’ve had since setting up the fish tank a few weeks ago, is that the trickle of water going back into the tank from the filter has been blowing tiny particles of sand out of the way, creating a giant crater in the sand and revealing the glass at the bottom of the tank. I tried to solve this by placing the Swell log with plants under the stream but this only broke the fall a little, as the sand underneath was still getting blown away. I then added some Swell Nordic gravel around the log and this seemed to do the trick – it looks good teamed with the sand too.

Water change

If using a gravel cleaner like the one I used, water is sucked out of the tank along with the dirt from the substrate, saving you the job of having to use a jug to remove water ready for a water change. It’s generally recommended that fish tank owners do a 20-25% water change once or twice a week, but you might want to remove a little bit more water if you’ve been having problems. Avoid doing water changes over 40% as the difference in temperature and water quality can shock the fish and make them ill. Remember to add dechlorinator to your water before adding it to the tank. I’ve been using API Stress Coat which removes chlorine, chloramines and ammonia from tap water. API Stress Zyme also helps to help clean a dirty aquarium and to reduce dangerous conditions such as ammonia, low oxygen levels and nitrite poisoning.


Treatments and additives

If you’ve had problems with water quality like I have, treatments and additives can come in handy to remove harmful chemicals and to replace them with beneficial bacteria and minerals. Ammonia is one of the worst things that you can find in your fish tank and so a good quality ammonia remover is worth purchasing. Evolution Aqua Pure Aquarium can also be beneficial to maintain crystal clear and healthy aquarium water, by using live bacteria and enzymes to break down the ammonia and nitrite within the aquarium.

Don’t overfeed

Last but not least, do not overfeed! It is often said that a fish’s stomach is roughly the size of their eye, while this can of course vary from species to species, and is not an exact indication, it can give you a clue as to how often you need to feed them. Some people feed their fish a tiny amount several times a day so that their fish can graze on the food, but this isn’t always ideal. Feeding every other day is also acceptable and even less frequently if you have a problem with ammonia.


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