Originally Posted by Ingy
Most play sand is granite sand. Although silica is present in granite, it CANNOT be consumed by diatoms as it is a very tight molecular structure. Just like the glass sides of the aquarium it is not a diatom feeding ground.
Coral sand and rocks are much more likely sources of silica:
Diatoms consume silica
Corals eat diatoms
Corals make their hard structure out of things they consume including the silica from diatoms.
Dead corals become rocks and wear down to sand.
Those rocks and sand have molecularly loose silica in them which CAN feed the diatoms
And the circle of diatoms continues.
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Thats making quite a few assumptions ingy. Youre assuming the ay sand is a pure granite sand without other minerals mixed in. I dont know about you but all the play sand ive ever seen seems to be a jumble of randomness.
Ive seen the exact same argument made for a silica based sand I use for my cichlid tanks. I always have issues with diatoms in those tanks and its quite obvious that the sand is the culprit despite wide spread belief that the silica is locked away through some crystalline process never to see the darkness of a diatoms stomach again. However, with a little testing if can be easily seen that its a potent source of silica in the aquarium.
Follow the kiss rule for aquariums and keep things simple. The simplest explanation is correct more times than not.