it is the first time im going to be changing my foam. in my filter ive had it a year and i read change it every 12 month.. how should i do it put the new one under the old one for a few weeks. so i dont upset the water. or just put the new one in and remove old strait away. im getting this one service kit.
http://www.aquatics-warehouse.co.uk/cgi-local/ca000004.pl
http://www.aquatics-warehouse.co.uk/cgi-local/ca000004.pl