Reef Chemistry Question of the Day #120 Nitrate and water change

Randy Holmes-Farley · Apr 26, 2015

Suppose that the water in a reef aquarium has a nitrate concentration of 50 ppm and a new batch of artificial seawater at the same temperature has no nitrate in it. If 10% of the water in the aquarium is replaced by the new water, the final nitrate in the aquarium will be closest to which of the following values?

A. 48 ppm
B. 45 ppm
C. 25 ppm
D. Not enough information is provided to properly answer

Good luck!

.

glb · Apr 26, 2015

45ppm.

ozzymac86 · Apr 26, 2015

I think D

shornik · Apr 26, 2015

It seems like B but I'm guessing that can't be correct.

fuzzone99 · Apr 26, 2015

B. 45ppm

sanglukwoohoo · Apr 26, 2015

B. 45ppm. Where can we find the answer?

ozzymac86 · Apr 26, 2015

B is to easy. Must be something else.

Devildoc · Apr 26, 2015

My answer is A

Stretch · Apr 26, 2015

I've always been told that nitrate reduction via water change is directly proportional to the amount of water changed.

I would guess B.

joshbbert · Apr 27, 2015

I thought 40ppm so B

Randy Holmes-Farley · Apr 27, 2015

sanglukwoohoo said:
B. 45ppm. Where can we find the answer?

I give the answer to these questions after being posted for a few days.

glb · Apr 27, 2015

If I was right do I get credit for being right first? [emoji3]

Rausch · Apr 27, 2015

I say A - if the closest number is rounded up, haha

hart24601 · Apr 27, 2015

I am going with D. How is the water being replaced? All at once by removing 10% and adding 10%, or is it removed and replaced at the same time, or as I do my WC adding 10% before removing 10%... although it all probably is a small enough difference to round to the same number.

EDIT: 45ppm by removing 10% and replacing, 45.45 by adding 10% before removing 10% if my math is correct, so I am guessing that is close enough to 45%.