Comparing square roots of negative numbers

If we have for instance $\sqrt{-25}$, that is, a square root of $-25$, I know the answer can be $5i$ (Is $-5i$ also correct? Sorry not professional in mathematics).

My main question here is how to compare square roots of negative numbers.

For example, which is larger, $\sqrt{-11}$ or $\sqrt{-13}$?

Thanks.