Question 698488
The volume of the pool is 18 X 10 X h where his the height(depth) of the pool this will give 180h m^3.
The flow is 0.6 m^3 per minute.
This flow has to 'spread' over the area of the pool surface. 
Thus the height that the flow 'covers' is given by
h = {{{0.6/180}}}m/min
thus h = {{{1/300}}}m/min
or h = {{{1/3}}}cm/min (this is 1cm every 3 minutes or 20cm every hour)