title: Adding 30 minutes to time formatted as H:i in PHP
body: <p>Having a nightmare at the moment and just can't see why it isn't working</p>
  
  <p>I have a value in the form H:i (ie 10:00, 13:30) etc called $time</p>
  
  <p>What I want to do is create two new values, $startTime which is 30 mins before $time and $endTime which is 30 mins after $time</p>
  
  <p>I have tried the following but just doesn't seem to want to work</p>
  
  <pre><code>$startTime = date("H:i",strtotime('-30 minutes',$time));
  $endTime = date("H:i",strtotime('+30 minutes',$time));
  </code></pre>
  
  <p>If I pass through 10:00 as $time and echo out both $startTime and $endTime I get:</p>
  
  <pre><code>$startTime = 00:30
  $startTime = 01:30        
  </code></pre>