You don't use soda. You use Chlorine or Acid if it needs. Go to a pool supply co. & consult. they will get you set up.
Depends on the depth of the pool
5.ooo to 65oo gallons of water
A 20 foot round pool has a radius of 3.2 feet. So the pool has a volume of pi*r2*h = 101.86 cubic ft approx.
I don't know how much salinity is in fresh water.
3% of the earths water, is fresh water
You should not put any Earth in your 18 foot round 5 foot deep pool. You should only put water and cleaners in the pool.
Fresh water freezes much much quicker.
3% is fresh, but 1% is for drinking.
well there is 30% in the salt water but is that the natural water is more fresh
The Pacific Ocean is salty, there is no fresh water in it.
fresh water doesnt have saltinity in it but, ocean water does.
Assuming you mean "How much of the water on Earth is fresh water", about 5% of the water on the Earth is fresh water, as opposed to about 95% salt water. To anser your question directly though, 100% of the fresh water we know about is on Earth. There is some water on other celestial bodies, but I wouldn't exactly call it fresh water.