understanding the numbers on a sump pump and which one to buy

ksimpson

I live where basements are usually wet. I have 3 drain pipes inside running to two basins. The outside wall was done by professionals for over $10,000 but did not keep the middle to inside basement floor dry. I put a drain in middle floor and along the inside wall (which I share with my neighbor). The professional pump system died. I am using a pond pump to pump water from its basin ( 10 to 15 gallon basin with two sump pumps in it one for back up and one to plug into the wall) to the basin I put in (20-30 gallon basin). I don't understand the 1/4 or anyother numbers relating to the sump pump. I do know I don't want a utility pump. I want a sump pump that will leave as little water in the basin as possible. The sump pump that I have-that works-leaves at least five inches of water in the 30 gal. basin before and after it comes on and goes off. I need a pump for the professionally done smaller basin. Also, will I need two separate back up systems or can I incorporate one system for both. Lastly, Can I recharge/reuse the batteries from the old system? If not, how do I dispose of them?