It looks like the pumps are somewhere around a 6 amp draw.
For a battery, it'll say "RC" (Reserve Capacity) or "Ah" (Amp Hours)
For RC, if it says 120, that's the number of minutes it will provide a 20 amp load without the battery falling below 10.5 volts.
So....
120 minute reserve (at 20 amps) = 2400 amp minutes.
2400 amp minutes = 6 amps for 400 minutes = 6.67 hours.
Ah
If your battery says a value for Ah, that's the number of hours by amps.
E.g. if the battery says 100 Ah, it can supply 1 amp for 100 hours or 5 amps for 20 hours.
All that said, the bigger your battery is in RC or Ah, the slower it'll discharge. A slowly discharged battery will last longer then one that's discharged quickly. So, the bigger the battery you get, the longer it should last. When charging, a slow charge is better then a quick charge. It's best not to charge at over 10% of the CCA rating of the battery. E.g. if it's a 650CCA battery, it's best not to use the 10 amp or larger charge option from your charger. Use the 2 amp option and let it go overnight.