How much hashpower would I require to surely mine one block per day? How much hashpower would I require to surely mine one block per day?
Divide this number by the number of seconds in a day (86400) to get the required number of hashes per second to solve one block per day on average. You might get more than one block on some days and no blocks on others. It's random.

Currently, you'd need about 931 TH/s, which is a ridiculous amount of mining power.