Yes!

Thank you everybody once again. 0, 0, 233 worked. Maybe a bit more may work too but I just wanted to be sure.

My problem was map_heights.hgt. Don't know why, because I was deleting everytime and generating a new one, but the .hgt file only made the problem worst.

After this there were still a few triangles showing here and there but your advice Red Spot worked like a charm.

Thanks Maka and RS!