I have an old sand filter from a previous pool and just purchased a new pool and a new filter comes with it. Would it be possible and useful to put both filters in line for better results.
Welcome to TFP! While in some cases we think of "more is better", this may not be the case using two filters. Big reason being water hydraulics/pressure available to support the equipment. Typically a pool filter and pump (motor) are paired together to ensure the filter has just enough water pressure to perform backwash and filter operations properly. Too strong (or weak) can actually have negative effects.
I would stick with the new filter and ensure you are always using a skimmer sock in the skimmer(s) to catch the fine debris.
Other than that, maintaining an ideal chemistry per TFP recommendations and you should do fine.
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