# Fert dosing vs nitrate reading



## EA James (16 Apr 2020)

Hi all,
My tap water reads 5-10 ppm for nitrates, yesterday I did a 60% WC on my 330 litre tank. 
I tested the tank water later that evening and the readings were 0ppm using an NT labs test kit




As you can see I don’t have a great amount of plants so I’m quite surprised at the tank readings. 
I dose 6ml of TNC complete daily so already slightly over the ‘recommended’
I’m going to be rescaping soon and adding a good amount of plants but I’m now unsure as to what I should do moving forward with regards to dosing.
I’m relatively new to this and want to make it right!


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## tiger15 (16 Apr 2020)

According to dilution calculation, your resulting nitrate level immediately after WC should be between 2 to 7 ppm.

Do you use the same NT test kit to determine the tap water nitrate or rely on utility water reports?  Nitrate test kits that rely on color comparison is good to read levels above 10 ppm, but poorly below 5 ppm.  So 0 ppm could mean non detectable at 1 to 5 ppm.


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## Zeus. (16 Apr 2020)

*What about test kits*

I better plan would be to get the water report form your water supplier, which will tell you the range of NO3 over the year, use the lowest value to the NO3 your adding and add extra NO3 to meet your tanks needs.

Trouble with testing the tank water is there are so many different ions in the water it can/does interfere with test kits results


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## EA James (17 Apr 2020)

@tiger15 yes using the same kit. So if it’s between 2-7 Is that good??

@Zeus. I'm sorry I don’t understand! How will I know how much the tank will need? 
Is there a test kit that you’d recommend? 

thank you both for your replies


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## Zeus. (17 Apr 2020)

EA James said:


> s there a test kit that you’d recommend?



No - just the water report and take the lowest level of NO3 mg/l (ppm)



EA James said:


> I'm sorry I don’t understand! How will I know how much the tank will need?



your plants will tell you or you will dose to suit a regime - say EI ferts

eg

Say your choose to follow Clives EI dose so 20ppm NO3 per week

Your tap water has say 12ppm NO3 and you do a 50% WC so you have increased the [NO3] by 6ppm NO3, therfore you add over the week another 14ppm NO3 and in total you have added 20ppm NO3 which in this case fits Clives target

or just dose the NO3 in excess by ignoring the NO3 in your tap water, its your call.

How much NO3 is enough? well when plants are healthy they have enough


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## EA James (20 Apr 2020)

@Zeus. sorry about the delayed reply.
Ok plenty of reading there for me! Thanks for the link that’s quite an interesting article and one I’ll need to read a few times to fully absorb it.
I wasn’t warned about the sheer amount of knowledge needed to keep a healthy planted tank! I feel like I’m back to school 
Thanks for your help


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