**Re: Liza's 20L Nano Tank**

Thanks, Mark, and many thanks for the formula. I looked into it and my tap water contains 11,8ppm NO3.vauxhallmark said:Good luck with this great tank

Your calculation now looks like this:

In cell A1 type "11,8"

In cell A2 type "=A1+5.9"

In cell A3 type "=(A2/2)+(11.8/2)+5.9"

Is this how I'm supposed to factor in the tapwater contents for the 50% wc?