Any reason why you aren't taking a custom white balance?
Basic 101 UW Color, using no strobes.
It makes your reds easier to recall if you first attach a UR pro red filter, then do a custom WB at the depth you are shooting, then you don't have to do much if any cast correction... Do you even have a slate to white balance on? The best slate on the market is the Amphibico #2 Blue. For Video and Stills, I get saturated beautiful images, with little or no effort, and if not lighting this in any way it is not complicated at all. What YOU are doing in post is falsifying the pixels which can't look as good as if you shot it right from the the beginning. Plus you can't batch correct with accuracy if any of the lighting conditions change [which you can from underwater if you keep adjusting WB to suit the ambient light] - easy!
Then on post : Adjusting colour casts for UW is as simple as using the Hue and saturation tool on a separate adjustment layer, either before and/or after some levels on an adjustment layer, which, if you know how to throw in a mask for difficult sun situations is all you need. If you shoot at 100ft with no red filter, no custom wb, you will not get real colours back from any method to work on in post. You need two things: plenty of LIGHT and WB set at depth.
Work the leading colours ie blue or green in H+S / then adjust for balance on Levels, noting the histogram's info:
This shows the Shadow Mid and Highlights, for R G and B, - work the sliders towards the edges of the histogram in each R, G and B inside levels and dont clip into the histogram or your contrast levels will be out.
Well, firstly without doing any post work I think you should try WB adjustment to a custom manual setting. If you dont have a slate as I described you can use a white slate, but it won't bring your saturation out, just as the grey slate is the same, but try white to start. Pippeting the white areas is IMHO hit and miss.
here is the slate:
Cases & Accessories :: Colour & White Balance Charts - Amphibico Underwater video Housing Store
Good luck, happy shooting
Eddy