MWB via housed Colormeter?

I am new to video. Once tried Hi8 with a Sony TR101 in a Gates housing long time ago. Only remember hastle of adjusting MWB everytime I went down or up in depth.

Now I have upgraded to a 7D and plan to use it for video as well. I like using my Tok10-17 for WA ambient.

Topside I like to use an expodisc to set my WB.

Nauticam makes dome with WB, but is costly. There must be other accurate ways. I know about the "guess" ways of using your palm, point into the sun (not recommended by Canon), white slates, white fins, etc.

I have this ancient Gossen Sixticolor color meter that gives me readings in Kelvins.

My question is:

1.Would this simple meter be useful (in a housing) for accurate MWB readings and setting for the 7D?

2.If not, what be a more accurate MWB technique to use on my 7D with a Tok10-17?

HD clueless, but learning anew.

Bo

Bo, is this regarding MWB for stills, videos, or both with the 7d? For all my video set ups, I use either the Amphibico White Balance slate, or we now have the DSC Color labs underwater white balance slates. Both work exceptionally well underwater and are easy to use.