I personally don't use red filters anymore as they "swallow" too much light and I don't like getting it back through "gain" as the picture quality degrades a lot. It looks grainy which I can't stand.
In my Gates housing I have 3 white balance switches. One is preset which can be set to outdoor or indoor. I use indoor here ( which gives a bluish picture) to compensate my halogen lights. the 2 other switches are manual settings for white balance. Switch A I balance on Land to a very red tone ( this compensates for the red filter, I achive this by white balancing against a blue background)) and the switch B I adjust underwater depending on the situation. I usually use a greyish background to white balance against, in my case grey sponges work very well. This way you are pretty good with macro and white angle. Of course every day is different and if the visibility is bad it's always hard to get good results, but final cut and a lot of patience takes care of the rest. Anyhow I agree with Dave, try to get it as good as you can underwater and not in front of your computer.