Dealing With High Nitrate in Tap Water

If you’ve been performing regular water changes but your nitrate levels are refusing to drop then it’s highly likely that you have nitrates present in your tap water.

We’ve spoken in previous blogs about the importance of keeping nitrate levels under control in our aquariums. This can be achieved a number of ways but the most common is by performing regular water changes. However, it’s becoming increasingly common for our tap water to contain large levels of nitrate.

The whole concept of water changes is to remove dirty contaminated water and replace it with nice fresh, clean water. Thus, diluting the contamination. However, if the water going back in is almost as contaminated as the water coming out then it can seem like an uphill struggle.

First, I’d highly recommend testing your tap water. If it contains 0ppm nitrate then it just means that your current water change schedule isn’t sufficient and you need to perform larger water changes and more frequently, or reduce stock levels. If there is a nitrate reading in your tap water then you need to consider some other options.

With a reading of 20ppm or higher, water changes alone won’t be enough to combat the problem. We need to look at other methods to reduce nitrate such as.

  • Reducing stock
  • Reducing food
  • Feeding better quality food
  • Introducing live plants
  • Using a nitrate reducing resin
  • RO Water

Reducing stock
This option is directly linked to reducing food. It’s the food that generates waste which in turn produces nitrate. With fewer fish in your aquarium, you’ll feed less food which translates into less waste and less nitrate.

Feeding better quality food
Cheap, poor quality food contains fillers that provide little benefit to your fish. These fillers will pass straight though and break down producing waste. Making the switch to higher quality food means you’ll need to feed less, resulting in less waste. Another benefit is that higher quality food will result in healthier fish.

Introducing live plants.
Plants are incredibly beneficial. They consume ammonia, nitrite and nitrate. They also produce oxygen and provide a natural hiding place for fish. Do your research first to make sure that the fish that you keep are plant safe. Also, if you’re new to keeping plants then steer clear of some of the more advanced options. Great beginner friendly species are Cryptocoryne’s and Vallisneria. There are countless others that are easy to care for but those two are my favourites.

Nitrate reducing resin
There are a number of resins available that work very well at reducing nitrate. However, they do need recharging regularly in order to remain efficient. There are 2 brands that I have experience with, API Nitrazorb and Countryside Aquatics C3 Nitrate Reducing Resin. Both of these come in a mesh bag which fits inside your filter. They are both rechargeable using a strong salt solution. I’d recommend getting a couple of bags so that you have one in use in your filter and another soaking in the salt solution. Just make sure that there is space in your filter for these before purchase.

RO Water
RO (Reverse Osmosis) is water that contains absolutely nothing. No minerals, no chlorine and no nitrate. This water can be bought from a local fish store or you can buy an RO unit to produce your own at home. The main drawback with this particular method is that you need to add minerals back into the water. This can become very costly labour intensive if you have a large aquarium. If you choose to buy your own RO unit then you should be aware that it takes a long time to produce the water and wastes a considerable amount in the process. Around 75% of the water that enters the filter is sent straight down the drain.

Each of the above methods will help to resolve the problem, however it’s not a one size fits all. A lightly stocked tank will probably only need some live plants added, however a heavily stocked tank may need a more robust approach. Personally, I have very heavily stocked aquariums and I use a mixture of the above methods along with RO water to combat the 40ppm I have in my tap water.

In a previous post I mentioned the ideal nitrate ranges that we should aim for, however if dealing with high levels in our tap water, we may need to be a bit more realistic. I’d still aim to keep nitrate levels below 40ppm but if it creeps a little over this level then I wouldn’t start panicking. It’s just a sign that we need to try some additional methods.

I hope this helps you to overcome one of the most frustrating issues present in this hobby. If you have a different method that works for you then please leave it in the comments. Also leave a comment or contact us if you need any further advice.


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