ghash is fee free yes but you have to withdraw via cex which has some of the highest fees around! cex are activly telling people to mine elsewhere because they are not making enough money from everyones hardware, they want people to buy their 'cloud mining' so they can such the life out of everyones money. i left cex/ghash due to their fees eating up over 75% of mined btc even though they claim they do not take that much. as time goes on there will be more and more block at cex that you will gain a -ve reward at the time i left it was about a 1 in 10 where it cost me to mine with cloud that equated to a loss more than 20% of the time. they are turning into a scam site!