I've been running this remote deep sand bed for about 2 months, and i notice that a great proportion of the top sand turns into greyish dark colour. Originally the sand was white. However, the bottom part of the sand remain white. I was able to see this because i put the sand on a square aquarium and locate it beside my sump. Is this discoloration because the phosphate binding thing? Hopefully someone in this thread could help me.
Thanks,
Kelvin
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