New to Saltwater: Help Please for 15ppt

[Sarcosuchus]

I have two tanks :

1) 3ft x 1.5ft × 2ft
2) 4ft x 2ft x 2ft

I want to achieve a salinity of 15ppt.

How many kilograms of sea salt should I add to these tanks to achieve a salinity of 15ppt?

When I asked the shopkeeper he said 3kg salt for the 3ft tank and 4kg of salt for the 4ft tank to achieve 15ppt.

 

[Mbargas]

I have two tanks :

1) 3ft x 1.5ft × 2ft
2) 4ft x 2ft x 2ft

I want to achieve a salinity of 15ppt.

How many kilograms of sea salt should I add to these tanks to achieve a salinity of 15ppt?

When I asked the shopkeeper he said 3kg salt for the 3ft tank and 4kg of salt for the 4ft tank to achieve 15ppt.

15ppt would be 15 grams of salt in 1000 ml volume, i.e. 1 liter

You don't really know the total volume in each tank, since some of the space is occupied by substrate, rocks, etc. It is also not filled to the brim.

You can guesstimate the volume:

1) 3ft = 91.4 cm
1.5 ft = 45.7 cm
2 ft = 61 cm
multiply all lengths to get 254,795 cc (ml) or 255 liters
multiply 15g x 255 = 3,821g or 3.8 kg, but of course you would use less since your actual volume would be less.

so 3 kg would be a good start, then measure the salinity and add more as needed

 

[Gourami Swami]

You definitely need a refractometer or other salinity meter, can't just assume you've got it right based on math. I won't attempt to do the math and you shouldn't need to either, just start mixing, check, add some, check, etc.

 

[Mbargas]

You definitely need a refractometer or other salinity meter, can't just assume you've got it right based on math. I won't attempt to do the math and you shouldn't need to either, just start mixing, check, add some, check, etc.

Of course, check the salinity

The calculations are just a staring point.