Maintaining you fish tank regularly is the vital to keeping happy and healthy fish, but what does this maintenance include?


Naturally the bacteria in the filter will break down harmful waste levels but over time nitrates can build up. Unfortunately, nitrates are invisible and odourless so can only be detected with a test kit, however we recommend having a regular weekly water change in place to keep them constantly low eliminating the need to test so frequently.


So how much water should I change?  

There’s no set ratio. This changes from tank to tank. Generally, 25%-50% is a good basis to start with weekly. Going on the higher end of the scale for large messy fish, highly stocked tanks and smaller filters.


As aquarium equipment and media has developed over time, pollutants in the tank are reading lower and lower. However, water changing isn’t just for diluting waste…


What does water changing achieve?

  • Dilute pollutants in the water

Mechanical filtration and biological filtration play an important role of breaking down waste by using the nitrogen cycle, however home aquariums cannot process nitrates very well. Fish can be much more tolerant of this waste compared to ammonia, but it can cause major stress leaving them prone to health issues and illness.

  • Helps with fish health and growth

Fish produce a growth hormone and when that is diluted regularly the fish will grow growth can be stunted by small tanks or tanks with high levels of this hormone.

  • Replenishes vital elements

Elements and minerals can often be removed through filtration. Make sure if you use reverse Osmosis water that you are adding a separate buffer as the purifying stages remove the elements.

  • Water clarity

Helps with overall discolouration and cloudiness, this leads to better light penetration which is especially relevant for planted aquariums.


Gravel cleaning


Dirt and debris collect over time at the bottom of the tank, this comes from breaking down organic matter. Fish waste, excess fish poo and decaying plant material. So an essential part of your maintenance kit should be a gravel cleaner. When choosing the right one you will come across lots of different brands and types from the basic syphon tube to more techy mains powered versions. Remember though, there’s no need to break the bank, they all achieve the same result! My personal recommendation would be a hand start syphon, its simple but effective. No need to suck on the end of a pipe to get stared and very simple to use.


Filter maintenance

How often you clean the filter depends on the type and the size of it. As a rough guide a external filter would need monthly maintenance and internals every couple of weeks. Ideally you would clean half the filter at a time, making sure not to wash away all the good bacteria. When rinsing use a bucket of your tank water as the chlorine in the tap water will kill of the bacteria.



Despite the different brands selling replacement sponges they are not actually necessary. Sponges can be rinsed regularly and used over and over again. Their purpose is to trap the larger particles.



The most common would be carbon which needs replacing every 6 weeks. You can tailor the chemical media to what you tank needs, so if you have lots of algae use phosphate media again replacing every 6 weeks.



This is the little spindle inside the filter, it spins round and round to make the water flow through, its important to clean this regularly because any excess debris that gets caught up inside can dislodge it or block it and cause it to overheat.


O rings

O rings are mainly on external filters, their duty is to make the unit watertight. Generally, they need replacing yearly but if you can take them and clean every once in a while, check there are no rips or tears to cause unexpected leaks.



Types of filtration


Biological- The nitrogen cycle.


Mechanical – Filters, Air pumps, uvs.


Chemical- Supplements such as Tap water conditioners, salt, plant food, co2 and medicines.


Which do I need?


All of them!


Biological filtration plays a massive part in breaking down waste mechanical filtration emphasises that. Chemicals are not a must but are more useful for targeting specific issues such as algae growth or disease. Some people are wary off using chemicals at home but there are also more natural versions which work using specific bacteria strains to deal with waste, or tea tree oil to treat illness.