Biologic evolution

Sand has flowed into a lower filter of the water tank.
With this, because the water current doesn't flow into sand, the
experiment is not meant.
The water tank is scheduled to be redecorated newly devising it.
The tool in the do-it-yourself store
Pracas and the pinko pickpocket towel were bought.
The cheap one was chosen as much as possible because it was high
whether failed.
The water tank tomorrow is scheduled to be redecorated.

It was unexpected to be able to have done the air hole by the water tank
experiment in sand.
Can the air hole be done sand in an actual sea?
Hypothesis 1
It is possible to do by the water current.
Hypothesis 2
When thinking that sand becomes soft in summer about the relation
Does the nourishment collected under sand ferment according to the height
of the temperature of summer and is the bubble put out?
Is the one like "Potting compost" used for the nutrient of the flower
under the sea sand?
Are not you because the temperature of seawater is necessary to ferment
and the height of the temperature is necessary?