Calcium chloride maths help please

[Liamnhayley]

I have a bag of "PQ Calcium Plus" calcium chloride.

First batch of Randy's recipe I mixed up a 10L container using a calculation of 500g p/3.8L or 1,315g p/10L
This solution never seemed to match reef calculator so thought I would try and mix smarter batch this time.

PQ calcium plus says on bag that 100g will raise 10,000L 10ppm. So I calculated that 37g p/1L = 37,000ppm (- Randy's mix number) or 370g p/10L.

To see what to had mixed in first batch I calculated ppm based on 1,315g p/10L and came up with a number of 131,500ppm (if my maths are correct?).

Through trial and error I'm now close to the consumption number at approx. 150ml of this solution a day which would equate to 1,972ppm per day!
Could this be right??? Tank is only lightly stocked 300L.

Please help me understand. If these numbers are correct I'm going to need to work out some larger auto dosing containers.

Cheers

[Onsan]

per = / = divide, all the same thing, so instead of 500g p/3.8L, just write 500g/3.8L.
the / tells you that if you divide 500g by 3.8L you would get 131.57g/L, or 131,578mg/L or 131,578ppm.
It's a small thing, but it helps to understand what your doing and where you may have gone wrong when checking your calcs.
I also recommend using mg/L instead of ppm, again it just helps understanding your calculations if you stick to weights and volumes.

1st.
100g will raise 10,000L to 10mg/L of Calcium Chloride. Not Calcium.
As Ca is 36.1% of the molar mass of Calcium Chloride it will raise Calcium by 3.61mg/L.

2nd.
Yes, 131,500mg/L of Calcium Chloride. 47,484mg/L of Calcium.

3rd.
No. 1,972mg/day of Calcium Chloride is added to the system, need to factor in dilution volume (tank size).
So; 0.15L x 131,500mg/L / 300L.
Gives 65.75mg/L/day of Calcium Chloride or 23.74mg/L/day of Calcium.
This is where using mg/L instead of ppm would have helped by reminding you that it is mass in a volume of water.

[Liamnhayley]

Thanks mate. I'll remember this correct format for per "something" when I'm quoting jobs at work!

Maths has never been my strong suit and quite obvious by the misunderstandings I have made in my calculations. I appreciate you clearing it up for me. I'll recalculate based on actual calcium component and see how I go.

Thanks again mate.