On occasion, there can be a need to adjust the hole location for Wittclips or rope in order to make your drop in liner fit properly. Fortunately, it’s a simple fix.
The most common method for fastening a tank liner is to use Wittclips or a drawstring rope. With thicker gauge liners holes are punched along the top portion of the liner (see this blog post on holes vs. grommets). The location of the holes is based upon the width and thickness of the top rim. Sometimes these hole locations need to be changed during the installation. This could be for reasons like wrong rim dimensions given at the time of tank liner fabrication, uneven dimensions of the top rim, or tank supports fall where the hole is punched.
Changing the hole location is very easy to do. All that is required is a hammer and a ¼ in. hole punch. The new hole can be located wherever is needed and punched out. The liner will not want to tear where a new hole is punched nor where the old hole was located. You can also use a drill with a 1/4 in. bit t0 make new holes. With new hole locations you should be able to get the Wittclips to fit as intended and have a great fitting tank liner.