Hi, due to the small size of my tank (50 lt) i dose macros via a liquid dose. I mix up enough nitrate and phosphate in separate bottles to last 3 weeks, the dry weights are calculated using the nutri-calc program and weighed using an electronic scale. The targeted values of each are 20ppm nitrate & 3ppm phosphate. If i use tap water in this mix will this react / reduce the amounts of nitrate & phosphate dosed into the aquarium?

Tank details:
50lt
1 55w AH PC tube & 2 18w NO daylight tubes
pressurised Co2 via glass diffuser with a power head sitting on top.
Flourite substrate
Gh 5.0, Kh 3.0.
3ml flourish 3x week
50% water change each week.

Should not be an issue.
But..if there is some NO3 and PO4 in the tap water, the accuracy may not be what you think, still, the excess will not hurt..........

Regards,
Tom Barr