As I know, the speed of the sound into a fluid is sqrt(K/rho)=14.9245 ft/sec, for your data and where K is the fluid bulk modulus and rho the fluid density. With your rho, in lbm/ft^3, this is the fluid density. You need g only if you have the specific weight gamma = rho/g. I know that a lot of books use rho for both: density and specific weight, and it's very confusing that notation.
Sorry all, when I was looking at this, it was at the end of the day, and I was dead tired. I used the wrong number for the bulk modulus of water. All is fine.