You must be down-under (OZ, NZ or SA) if summer just ended. I'm delighted the open water season is just starting here.
I agree the Tempo Trainer can be an incredibly helpful tool for gaining speed, but I have to raise the question how you'll reach your goal of improving your 1500m time by 3 minutes simply by setting the TT to beep at 31 second intervals, then 30 second intervals. What will you do BETWEEN beeps (i.e. between the walls) to ensure you reach the wall by the time it beeps?
How many strokes are you taking to complete 25m? You made no mention of that but it's the MOST critical number since Stroke Length correlates more closely with speed than any other metric.
Head Coach & Chief Executive Optimist
May your laps be as happy as mine.
My TI Story