If your scene consists of a shader glow in behind a semi-transparent object, you may find that your transparent object does not sufficiently occlude the shader glow. If this occurs, expand the Common Shader Glow Attributes section in the Attribute Editor of the shaderGlow node and uncheck Auto Exposure. Then, increase the Threshold value until the transparent object occludes the shader glow as desired. Decrease the Threshold value if you want to increase the shader glow instead.