<?php
$message = 'What will happen to the #globe if there is more #sunlight more #moonlight but less overall #light. Ah! Funny little #joke. Goodbye fellas!!! #Morning Jokes #For No one.';
$GLOBALS['_loops'] = 0;
echo "BEFORE : ", $message, "\n";
echo "AFTER : ", preg_replace_callback('~\h*#[a-z]+\h*~i', function($match) { return ' '; }, $message), "\n";
echo "LOOPS : ", $GLOBALS['_loops'], "\n";
BEFORE : What will happen to the #globe if there is more #sunlight more #moonlight but less overall #light. Ah! Funny little #joke. Goodbye fellas!!! #Morning Jokes #For No one.
AFTER : What will happen to the if there is more more but less overall . Ah! Funny little . Goodbye fellas!!! Jokes No one.
LOOPS : 0