What method of concrete placement will you be using?
1. Gunite (dry mix)
2. Shotcrete (wet mix)
3. Cast in Place
If your using Gunite, I don't think an air entraining admixture can even be added.
Check out the south florida building code. Available via construction school book stores. It is very detailed about the do's and don't of pool design keeping safety in mind along with some of the toughest building codes in the USA- Thanks to hurricane Andrew that hit us in the early 90's.
Pools...
WE INSTALL POOL PLASTER MOSTLY IN REGULAR SWIMMING POOLS. A CUSTOMER OF OURS IS BUILDING A SALTWATER SWIM POOL THAT WILL BE FILLED WITH OCEAN WATER LOCATED IN MIAMI, FL. WE ARE AWARE OF AND PLAN TO USE A SILICA-FUME TYPE POZZOLON ADDITIVE THAT WILL DENSIFY OUR MATERIAL AND MAKE IT LESS...