What kind of urea is this. There is regular urea, feed urea, and low biuret urea. Low biuret urea is what you want for fertilizing grass. I do not always have a choice as to how clean dry raw materials are, so several stages of filters are good.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738