Vet question

[Wrecksduke@aol.com]

One of my horses (who is not ridden much) pees at least two if not three times as much quantity-wise than our other horses.  As he is not ridden much, he gets "diet" size flakes of hay compared to our other guys.  They all get 2 teaspoons of mineral salt with their treats once a day.  He doesn't have a salt block in his feeder now.  When he does, he tends to eat it up fast.  I assume this is out of boredom and/or he thinks he's starving after eating his "diet" size flake and everyone else is still muching away.

My question is:
Is there any problem with a horse that pees "too" much.  He doesn't seem to drink that much more water than the others.  (Well, maybe he does..... I can't tell how much he drinks out of the barrel in the turn out area.)

Melody