Ice Standards

One of our more vocal members is really opposing us inserting our rocks. His concern is we have had the same set of rocks for 4 decades and they were just fine. We now have had them polished 2x in the past 7 years. We are now seriously considering having the rocks inserted but our member is concerned that there is something in our ice that is ruining the rocks.

I am thinking that one of the reasons we aren't so happy with our stones is the standards have changed for ice speed. So the old rocks when they were at their best wouldn't make us happy today. We do know if we have the inserted rocks they run 10-15% faster than our rocks(we borrowed a set).

So my question is does anyone have the standards for competitive ice from 10 years ago compared to today? Is there anything we should be checking that could be hurting our rocks? We have checked the PH of the ice.

Thanks again.