Graph Interpretation on Slush Pool I understand that a dar red line on Slush pool hash rate means a block has been discovered by the pool. 



What does the blue line mean around 5AM?
These are called Namecoin blocks and you can see your reward for all those blocks by checking out your reward section. You'll see a toggle above the rewards table on the right to switch between Bitcoin and Namecoin blocks. These blocks have a much lower value than normal Bitcoin blocks and so your reward is very small. The number of confirmations needed for these blocks is also very small compared to normal blocks. They are a by-product of Bitcoin mining and the pool uses a service to automatically exchange them for Bitcoins.