Thread: High readings for nitrate from tap water.

Morning All,

I'm getting completely different readings for nitrate from 2 different test kits from our tap water. First kit I have had since spring is Aqua Care ( made under licence by NC labs. for Maidenhead Aquatics) expiry date 07/2026, this reading is 2.5 ppm.

I also have a new API kit, recommended by Manky Sanke on this site a few weeks ago, this reading is between 20 & 40 ppm.

As well as my koi pond I have a tropical aquarium which is in the early stages of set-up (5 weeks) the nitrate reading from the tank water is very little different from the tap water from both test kits. I am suffering from algae in the tank and having to clean the gravel every 6 days & the glass twice a week. The pond is slowing down with the colder weather, the UV is off and the water is clear.

Thanks for any help or comments,

Brian

The second reading on the API kit stands out as being the accurate one based on typical values.

20 to 40 ppm would be pretty typical for a low stocked Koi pond being fed twice a day.

10 to 20 ppm is pretty typical for water from the tap depending on where your supply is from in Kent.

Nitrate tests are often a bit more involved than other parameter tests so double check you are following the instructions to the letter, i.e some have you shaking the bottle for 1 minute, and then vial for another 1 minute, others require you to add a powder to the vial etc etc.

What type of algae are you suffering from in the tank, brown algae, green water or string algae etc?

I used to always get brown algae all over the glass of my tanks within 7 days of cleaning it off, despite relatively low nitrate levels. Rightly or wrongly I put it down to the heavy mineral content (GH / KH - hardness) of Kent water supplies.

Thanks for that RS2000,

Yes, following instructions to the letter. I just don't see how 2 different test kits can give such different results.

I haven't checked the pond for nitrate for a while & this is the first time I have checked the tap water.

I am returning to tropical fish after a gap of about 20 years. I realise the tank is in the early stages of set up. The algae is green with some string algae and no brown algae, the water is clear, not green. I only have a few fish including the old favourites, neons, guppies also 3 small bristlenose plecos ,I'm feeding small amounts twice a day.

It's strange, but we received a letter from Southern Water on Tuesday advising us that " as part of the improvement upgrades at Martin Gorse Water supply Works we have installed a new nitrate removal plant that uses ion exchange to remove nitrates in the water" They go on to say that we might notice a slight difference in the taste of the water, cant say we have noticed.

Thanks again for your reply.

Brian.