I am currently working on my CYA numbers before I carry out working up to shock FC. My CYA is about 90 now and will be turning a lot more water over in the next day. I have found that when my pump is running a get a white like residue on the surface. Not sure what this could be from. It could just be the water or stuff dieing and ending up on the top. I had to replace one of my filter grids when i opened it up last which was last week. One of the grids support that locks into the manifold was broken and letting DE thue. to the returns, not much but some. Could this white stuff be still something from the filter? Pics below now. Thanks in advance