Simply Koi and More Koi

Hi all. I am after some advice, I currently have a 12ft x 13ft x 3ft pond which I want to raise by 2ft, I have a rienforced concrete ring 1ft x 1ft, what I want to know is are 9in x 18in x 4in blocks layed on there edge strong enough to take the pressure of the water or would I be better to lay them...