The Nitrogen Cycle

We love our fish at Brookside Garden Centre, and if you’re reading this, we’re assuming you do too. Get the details right, and you can enjoy the serenity they bestow without worry, and your scaly friends will be grateful, even if they’re not aware of it.

Back in October of last year, we created a blog post to highlight the importance of getting the pH levels right in your aquarium (click here if you missed it), but it’s not just the pH level of the water that has an impact on the health of your fish. With the help of the experts in our Aquarium Department, we’ve followed that up by taking a look at the part ammonia, nitrites and nitrates play, and what you can and should do to keep them at safe levels for your aquatic acrobats.

    

Ammonia is produced by fish waste, decaying plants and uneaten fish food, but adding too many fish to your tank too quickly can create a spike in the levels that can cause as much harm to them – death or disease – as the slower increase from lack of cleanliness. So, in short, ammonia is not good, BUT, it’s not all bad news… As ammonia levels increase, so too do Nitrosomonas bacteria, and these little miracle workers feed on the ammonia – their main food source – as quickly as it’s produced, lowering the ammonia to safer levels; they do, however, create a further problem… When feeding, Nitrosomonas bacteria produce nitrites, and too many nitrites can also cause a problem – the death of your prized fish – but fortunately, there’s yet another little gem waiting in the wings: Nitrobacter bacteria, and yes, you’ve guessed it, they feed on the nitrites, lowering the levels. In the main, then, nature will take care of itself, but the Nitrobacter bacteria will also produce waste, and that’s called nitrates. Whilst this last addition is less harmful than ammonia or nitrites, too much can still cause harm, and we don’t want that at all, and this time, there’s no natural, magic cure, so it needs to be you.

Adding live plants to your tank can help – moss is particularly good at removing nitrates – but remember that plant waste will increase ammonia levels, and thus the cycle repeats, leading you back to an abundance of nitrates. So what’s the answer? Regular water changes and cleaning; it’s the best way to keep nitrates at bay and your aquarium and fish happy.

    

With an established tank, you’ll make the whole thing easier by ensuring you don’t over-feed your scaly swimmers, and if you find leftovers in your tank, remove them with a net, along with any dead or decaying parts of your aquarium’s plants. When changing the water – unless advised to by an expert – never change all the water or scrub the gravel; instead, a 25% water change is recommended at least once a week, but the severity of the nitrate levels in your water will dictate the frequency of the changes; you should also clean the sides of the tank with sponges – fine and coarse are available – and algae magnets or scrapers, and any decorations you may have with bottle and/or nail scrubbing brushes. If you clean your filter media with tap water, you will kill the very bacteria you need to encourage, so clean it instead in water that you remove from your tank. As a rule, both ammonia and nitrates should be at 0ppm (parts per million) and nitrates at 0-10ppm, and tests are available for all three issues; if you are concerned about the health of your fish and need to test the water, speak to our Aquatics team.

Are you new to keeping fish? Did Christmas bring an unexpected aquarium into your life? Getting the levels right in your tank is essential before you add your swimming buddies, but it’s easier to do with water alone: add bottled ammonia to start the nitrogen cycle, filter boost products like Fluval Cycle, NT Labs Fitlerstart or Tetra Safestart or by adding a pinch of fish food to the aquarium as excess food will produce ammonia too. You can expect to see a milky haze to the water; this is a bacterial bloom, and it’s a very good thing to see, so resist the temptation to change the water, and just leave it to settle over the course of a few days; a water test at this stage will show no ammonia, only high levels of nitrites and nitrates. Testing regularly will tell you what stage you’re at in the cycle and when your aquarium is ready for fish – check ammonia and nitrites are 0ppm and nitrates are 0-10ppm – and we’d recommend leaving a new aquarium to cycle for at least a week before adding fish. Depending on the size of the tank, we’d recommend only adding 2-4 fish and leaving it for a week before adding another small amount, as over-stocking will lead to an ammonia spike.

    

Creating your own haven for fish may be a little more tricky than you’d expect, but once you have the basics covered, you can experience the joy of watching a bunch of colourful and adept swimmers inhabit an underwater world without the fear of losing any of them to inexperience, and as always, we’re on-hand should you need any further advice at any stage.