rite guys i have a 400l flat tank an i want to convirt it to a uprite tank im guna seal the scrue lid on an rachet strap it to tank so it wont pop off also the lid will b at the top so water wont b puting mch pressure on it now i need to cut a hole an make a new lid any iders how to go about this has any one done this b 4?? im think a plummers murchents will sell the stuff the lid can b small as ill only ever need to put a hose in it