Hedging with conventional grid approach may not be efficient, take a look at this concept: http://www.elitetrader.com/vb/showthread.php?s=&threadid=217539
In congruence with the above: Futures are CONTRACTS that are cash settled every day. When u win money is added to your account. It is not like a security such as a stock where there is a "holding period" that means anything significant. This mental confusion and your failure to know the SPY - ES ratio suggest that for best results you might study up before jumping in the ring.