Observe
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August 8 
Because we absorbed the dirt of the bottom, some bottoms become beautiful.
We was not able to see the bottom of the pond in algae and sludge so far. We was able to see the bottom of the concrete when we cleaned it.August 29 
In the pond of the school biotope, We put a stone in the bottom today.It was hard to be heavy, and to have. It looks like this puts the stone.
A bottom became bright and became easy to find killifish when we put a stones. 
