Nitrate levels ?

[dino21]

Hi,
Have an established 60ltr well planted tank with an equal number of fast and slow growers and a small number of healthy small fish, the substate is Molar clay with a sand topping.
Been using the APFUK ferts for a couple of years at the suggested level and growth etc is ok, but just prior to the water change the Nitrate level seems high at around 60-80 ppm ( api liquid test kit, tap water virtually 0 nitrate ).
Is this a typical reading for Nitrate using this method of fertilisation or is it too high and we should start halving our dosing ?

 

[dw1305]

Hi all,

........... Is this a typical reading for Nitrate using this method of fertilisation or is it too high and we should start halving our dosing ?

What do the plants and fish look like? Assuming they all look OK? Then I wouldn't worry too much. I actually think the values from the <"leaf colour chart"> and <"Duckweed Index"> are a pretty good proxy for nitrate content in the plant.

Been using the APFUK ferts for a couple of years at the suggested level and growth etc is ok, but just prior to the water change the Nitrate level seems high at around 60-80 ppm ( api liquid test kit, tap water virtually 0 nitrate ).

Try diluting the tank water before you test it, ideally with RO, but if you don't have access to RO your tap water will still give you an idea. Try 1 : 3 tank to tap and see what value you get (you will need to multiply by 4 for the NO3 level in the tank).

<"Test kits for nitrate aren't great">, mainly because of the solubility of NO3-.

You could try reducing the amount of potassium nitrate (KNO3), if you use dry salts?

Because potassium (K+) and nitrate (NO3-) ions are mobile in the plant, and the plant needs a lot of them, if they become deficient growth will slow and the older leaves will begin to yellow really quickly.

The good thing is that when they <"stop being deficient"> then greening and growth is almost instant.

........ In the case of nitrogen (N), potassium (K) and magnesium (Mg) they are all mobile within the plant, so when they cease to be <"Liebig's limiting nutrient"> you get, pretty much, <"instant greening">.

cheers Darrel

 

[dino21]

Hi Darrel, thanks for the reply,

The fish and plants are good and healthy with no recent losses, though initially we did have BB and Hair Algae but now just a little bit of BBA thats not a problem.

Don't have any true floaters, the nearest being a mop of Hydrocotyle , would say its on Mid area of the leaf colour chart, as are the submerged plants.
Also don't seem to have a problem with any real leaf die off, more a case of cutting it back as its all growing so well.

Just done a 1:3 nitrate test and its around the 15ppm mark so that confirms the earlier reading of around 60 ppm
Yes I'm still using the APF UK dry salts, probably still got enough for this decade !

Though we could reduce the Potassium Nitrate in the mix, we did wonder if we were equally overdosing all the other element of the salt mix ? and so should reduce the overall dosing ?

As a final check , might just run for a week or two but with a much reduced feeding regime to ensure its not coming from that, as we can all be guilty of that at times.

​

 

[dw1305]

Hi all,

Though we could reduce the Potassium Nitrate in the mix, we did wonder if we were equally overdosing all the other element of the salt mix ? and so should reduce the overall dosing ?

You could try recording <"the conductivity (TDS) level">. Conductivity doesn't tell you which ions you have, but if the value continually rises then you need to add a little less fertiliser or change a bit more water.

Have a look at <"Guide to TDS">.

cheers Darrel

 

[jaypeecee]

Nitrate level seems high at around 60-80 ppm ( api liquid test kit, tap water virtually 0 nitrate ).

Hi @dino21

Although I don't use the API Nitrate liquid reagent test kit, I have read that aquarists have had problems with it. So, this may be giving you inaccurate results. I use the JBL liquid test kits, including Nitrate. My experience with JBL products is that they are reliable.

JPC

 

[dino21]

Hi all,

You could try recording <"the conductivity (TDS) level">. Conductivity doesn't tell you which ions you have, but if the value continually rises then you need to add a little less fertiliser or change a bit more water.

Have a look at <"Guide to TDS">.

cheers Darrel

Over the year+ it has climbed a little, the tap water is a constant 80 ( HM Digital TDS-3) and before the weekly 50% water change its around 185 , originally more like 155, though does that count as a large rise over a year ?

KH and GH seem quiet constant at 3 and 6 respectively, though again API liquid test kits.

Will have to ask what brand testers the LFS use to see if they can confirm our readings, short of an expensive JBL test kit that @jaypeecee mentions.

 

[dw1305]

Hi all,

Over the year+ it has climbed a little, the tap water is a constant 80 ( HM Digital TDS-3) and before the weekly 50% water change its around 185 , originally more like 155, though does that count as a large rise over a year ?

No, that looks fine. As long as the plants and fish look healthy I'd just probably keep on doing what you are doing at present.

I would really like to know what the chemical parameters of my tanks are, but against that I'm a <"pretty shoddy aquarium keeper"> (and <"scientist">), <"a luddite"> and being a great believer in <"if it ain't broken don't fix it">, it just makes life a lot easier.

cheers Darrel

 

[dino21]

Thanks Darrel, know Nitrates at that level are not harmful as such, really wanted to check the dosing regime was ok, like you , we are not obsessive about minor fluctuations.

However keeping a close on the tanks temperature in these very hot days, just started to get a really hot (30c+) wind coming into the room, thankfully the overtank fan and the ATU are keeping things at 24c

 

[jaypeecee]

KH and GH seem quiet constant at 3 and 6 respectively, though again API liquid test kits.

Hi @dino21

The API KH and GH test kits should be fine. In fact, I use them myself for everyday KH and GH measurement. The API nitrate test kit is the one to avoid.

JPC