I have like 3-4 stems of Anacharis lightly wedged together with a plant weight. One of the stems the base about 1/2" has turned totally white/cream almost chalky looking, a little bit of the weight that is around that stem is white also. All the plants/fish are doing fine and the Anacharis in that stem and all others stems are growing fine. Any idea what it might be? I can try and get a picture but hopefully its nothing serious. Thanks.