Looping through query links via CURL and merging result arrays in PHP

The following code is supposed to search for a term on twitter, loop through all the result pages and return one big array with the results from each page appended at each step.

foreach($search_terms as $term){
    //populate the obj array by going through all pages

    //set up connection
    $ch = curl_init();

    // go through all pages and save in an object array
    for($j=1; $j<16;$j++){
        $url ='http://search.twitter.com/search.json?q=' . $term .'&rpp=100&page='.$j.'';
        curl_setopt($ch, CURLOPT_URL,$url);
        curl_setopt($ch,CURLOPT_RETURNTRANSFER,1); 
        $var[$j] = curl_exec($ch);
        curl_close($ch);
        $obj = array_merge((array)$obj,(array)json_decode($var[$j], true));
    }
}

It doesn't quite work though and am getting these errors:

curl_setopt(): 3 is开发者_Python百科 not a valid cURL handle resource
curl_exec(): 3 is not a valid cURL handle resource
curl_close(): 3 is not a valid cURL handle resource
...... and this is repeated all the way from 3-> 7...
curl_setopt(): 7 is not a valid cURL handle resource
curl_exec(): 7 is not a valid cURL handle resource
curl_close(): 7 is not a valid cURL handle resource

//set up connection
$ch = curl_init();
// go through all pages and save in an object array

for($j=1; $j<16;$j++){

You need the call to curl_init() inside your loop since you close it at the end of each iteration.