Ok math wiz people, help a guy out.
- Thread starter djkms
- Start date
jagermeister;103846 said:
48 ppt 
Encase anyone is wondering I am doing this to help maintain PH with my ATO and kalkstirrer. I am not evaporating enough water to maintain PH where I want it.
Darn it! Only got partial credit!
So, salinity is mass of salt divided by mass of total solution. So 35 ppt water has 35 g of salt in 965 g of water.
salinity = 35g salt/(965g water+35g salt) = .035
Now there's probably a lot easier way to figure this out but this is the approach I took.
First I figured out how much salt was in 5 L of your topoff water.
5 L = 5000 mL
1 mL water = 1 g water
Let x = grams of salt
.035 = x/(5000+x)
x = 181.3 g salt in 5 L of 35 ppt seawater
Next I determined, when you mix 5 L of topoff with 2 L of fresh water, how much more salt you need to add to bring that mixture up to 35 ppt.
Let x = additional g of salt
.035 = (181.3 + x)/(7000+181.3+x)
x = 72.586 g
So that means you would need to add 72.586 g of salt to your 5 L + 2 L mixture to create a mixture with 35 ppt salinity.
So, since your goal is to add this extra salt only to your topoff water, the final step is to determine the salinity of your topoff water after adding an additional 72. 586 g of salt.
Let x = salinity
x = (181.3 + 72.586)/(5000 + 181.3 + 72.586)
x = .048 or 48 ppt
Hope that makes sense.
So, salinity is mass of salt divided by mass of total solution. So 35 ppt water has 35 g of salt in 965 g of water.
salinity = 35g salt/(965g water+35g salt) = .035
Now there's probably a lot easier way to figure this out but this is the approach I took.
First I figured out how much salt was in 5 L of your topoff water.
5 L = 5000 mL
1 mL water = 1 g water
Let x = grams of salt
.035 = x/(5000+x)
x = 181.3 g salt in 5 L of 35 ppt seawater
Next I determined, when you mix 5 L of topoff with 2 L of fresh water, how much more salt you need to add to bring that mixture up to 35 ppt.
Let x = additional g of salt
.035 = (181.3 + x)/(7000+181.3+x)
x = 72.586 g
So that means you would need to add 72.586 g of salt to your 5 L + 2 L mixture to create a mixture with 35 ppt salinity.
So, since your goal is to add this extra salt only to your topoff water, the final step is to determine the salinity of your topoff water after adding an additional 72. 586 g of salt.
Let x = salinity
x = (181.3 + 72.586)/(5000 + 181.3 + 72.586)
x = .048 or 48 ppt
Hope that makes sense.