The best cheap way to do it is using custom white balance, since your camera doesn’t have that setting, you’re left with strobe/dive light, which mean extra stuff to carry and manage.
The next cheaper solution is adding a red filter. Look into that and see if they have red filter for your housing, worse case is you would just take a piece of red plastic and stick it inside of your housing.
Basically you need to understand what water does to light. As you go deeper into the water, the red color get filter out by the water, that’s why all your photos are very blue. You need to add more red back to the picture through filter, or use custom white balance so the camera know how much red to add back to the picture.