One slight correction ... the use of a "red" filter does not really "lighten" red colored areas; it simply darkens all else - especially blue (and to a large degree - green).

I'm not familar with a "90 Red", but it may be too severe for this application - but all that is dependent solely on the "vision" and intent of the photographer.

Try a less "severe" filter - Red 25, or orange ... or yellow....