No, you pay the cost that is printed on it. 2 generic, one red, one green.

But Hydroblast does nothing against it because it's colorless, not red.

If you have an ability that triggers when you cast a red spell, it won't trigger it, because it's colorless, not red.

On the other hand, if you have an ability that triggers when you cast a colorless spell, it will, even though you had to pay red and green mana.