I'm thinking of getting one of these: http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... NA:GB:1123 The filter i'm attaching it to (Tetratec Ex700), uses a pipe with 11.3mm internal diameter. However the glass is available in 10mm (too small), or 13mm. If i heated up the pipe, would it stretch to fit over a 13mm diameter? TIA!