Voltage question

[crackajacka]

i have a 86 gmc with everything almost stock, well i finally broke down and bought a optima DT34/78 deep cycle battery because i have added an some sub's. ok my question is with my old battery(which was broke and leaking acid) i could add water and charge it for an hour and put it back in and my volt gauge would read 13. when i bought my new battery i charged it for 8 hours at 10 amps on a auto charger, it said it was fully charged so i put it in my truck and now my volt meter reads 11-12 volts. Is this ok for this type of battery or is something wrong??? id appreciate suggestions.

thanks