strip blank lines from output

I have code which is creating a XML document for Google Shopping. Google is getting hung up on a blank line. I do not know how to strip the lines out. The code is pulling from a Magento Commerce database.

<?php echo '<?xml version="1.0" ?>'; ?>
<rss version="2.0" xmlns:g="http://base.google.com/ns/1.0" xmlns:c="http://www.base.google.com/cns/1.0">
<channel>
<title>Spray Foam Systems</title>
<link>http://www.sprayfoamsys.com/store/</link>
<description>Spray Foam Rigs, Spray Foam Equipment, Sprayfoam Parts and Supplies.</description>

<?php
$con = mysql_connect(REMOVED) or die(mysql_error());
    if (!$con)
        {
            die('Could not connect: ' . mysql_error());
        }
    mysql_select_db("sprayfoa_store", $con);

    $query = mysql_query("SELECT * FROM `catalog_product_flat_1` WHERE `visibility` = 4 ORDER BY entity_id ASC")
    or die(mysql_error());
?>

<?php
    while($row = mysql_fetch_array($query))
        {
?>
<item>
<g:id><?php echo $row['entity_id']; ?></g:id>
<title><?php echo $row['name']; ?></title>
<description><?php echo $row['short_description']; ?></description>
<g:google_product_category>Business &amp; Industrial &gt; Construction</g:google_product_category>
<g:product_type>Spray Foam Parts &amp; Supplies &gt; Fusion AP Parts</g:product_type>
<link>http://sprayfoamsys.com/store/<?php echo $row['url_path']; ?></link>
<g:image_link>http://sprayfoamsys.com/store/media/catalog/product<?php echo $row['small_image']; ?></g:image_link>
<g:condition>new</g:condition>
<g:availability>in stock</g:availability>
<g:price><?php echo $row['price']; ?></g:price>
<g:brand>
<?php
$entity_id = $row['entity_id'];
$query2 = mysql_query("SELECT * FROM `catalog_product_entity_varchar` WHERE entity_id = '$entity_id' AND attribute_id = '127'")
or die(mysql_error());  
    while($row2 = mysql_fetch_array($query2))
        {
            echo $row2['value'];
} ?>
</g:brand>
<g:mpn><?php echo $row['sku']; ?></g:mpn>
</item>


<?php
}
mysql_close($con);
?>

</channel>
</rss>

The output looks like:

<item>
<g:id>15</g:id>
<title>DK 817 - Gun Cleaning Solvent and Lubricator - Aerosol Can 16 oz. </title>
<description>DK 817 is a cleaner-lubricant used on for cleaning polyurethane dispensing equipment and guns.  DK817 comes in a 16 oz. aerosol can.  Contractors praise it's ability to quickly clean components with uncured polyurethane materials.  </description>
<g:google_product_category>Business &amp; Industrial &gt; Construction</g:google_product_category>
<g:product_type>Spray Foam Parts &amp; Supplies &gt; Fusion AP Parts</g:product_type>
<link>http://sprayfoamsys.com/store/dk-817-gun-cleaning-solvent-and-lubricator-aerosol-can.html</link>
<g:image_link>http://sprayfoamsys.com/store/media/catalog/product/d/k/dk817.jpg</g:image_link>
<g:condition>new</g:condition>
<g:availability>in stock</g:availability>
<g:price>24.9900</g:price>
<g:brand>brand
</g:brand>
<g:mpn>partnumber</g:mpn>
</item>


<item>
<g:id>16</g:id>
<title>Allegro Full Mask SAR Replacement Lens 9901-09L</title>
<description>Replacement lens for the 9901 Series Allegro Full Face Mask.  Clear, scratch resistant lens.  Easy to replace.  Lens only.

Allegro 9901-09L</description>
<g:google_product_category>Business &amp; Industrial &gt; Construction</g:google_product_category>
<g:product_type>Spray Foam Parts &amp; Supplies &gt; Fusion AP Parts</g:product_type>
<link>http://sprayfoamsys.com/store/allegro-full-mask-sar-replacement-lens-9901-09r.html</link>
<g:image_link>http://sprayfoamsys.com/store/media/catalog/product/a/l/al-9901-09l-1.jpg</g:image_link>
<g:condition>new</g:condition>
<g:availability>in stock</g:availability>
<g:price>75.0000</g:price>
<g:brand>
Allegro</g:brand>
<g:mpn>9901-09L</g:mpn>
</item>

The first item passes through no problem as the description tag has no blank lines, however the second item, give me a XML formatting error, the only thing I can think of is the blank line in the description tag

You could try stripping out the newlines like this

<description><?php echo str_replace(array("\r\n", "\n"), ' ', $row['short_description']); ?></description>

See the str_replace() function in the PHP manual.