during which phases of the moon are the high tides and low tides at extremes
Tidal range The most extreme tidal range occurs during spring tides, when the gravitational forces of both the Sun and Moon are aligned (syzygy), reinforcing each other in the same direction ([new moon]]) or in opposite directions (full moon). During neap tides, when the Moon and Sun's gravitational force vectors act in quadrature (making a right angle to the Earth's orbit), the difference between high and low tides is smaller. Neap tides occur during the first and last quarters of the moon's phases. The largest annual tidal range can be expected around the time of the equinox, if coincidental with a spring tide.
Full moon The interval period between a new or full moon and the next same phase, a synodic month, averages about 29.53 days. Therefore, in those lunar calendars in which each month begins on the day of the new moon, the full moon falls on either the 14th or 15th day of the lunar month. Because a calendar month consists of a whole number of days, a lunar month may be either 29 or 30 days long.