will be better if you can give us a picture.
I will guess is Diatom, do u use RO
check your paraM, if there r too much nitrate, diatom will start growing.
as some pro told me in here, diatom will burn out once they don't have "food" which is nitrate and silicate (forgot how to spell, but if you just use tap water, that will have silicate in it).
Thanks to AMD, HN1, Zero, partypalooza, thincat, and thominil who helped me in almost every questions. Thanks everyone!!!!!