i recently purchased a good amount of cularpa algae (grape clusters), some of the balls, not the whole clusters, are turning yellow.. i had the light bulb, (a plant light from home depot) pretty close to the surface, so i moved it away. i havent givin it enough time to see if that was the problem.. i also started dosing a bit of coralvite (a mineral additive), directly into the fuge. someone told me iron levels might be the problem.. does anyone know anything else that will help??