> Not certain I understand how vacuuming a tank makes things worst, unless you are saying it could give you a false sense of all >being well, but with debris remaining.

 

The issue with vacuuming a sealed tank from the filler hole is that once you stick a big sucking hose in the filler hole what you will get is a lot of in-rushing air around the nozzle that will blow bits of debris to the four corners of your tank. The air being sucked from the tank is replaced by air coming in the filler hole.  So, if you use a small hose – say ½” ID then the amount and velocity of in-rushing air won’t be as great and won’t disturb any debris that might be near the filler hole. Takes a long time to vacuum the tank with a ½” ID hose – but it’s the only way to do the job effectively.

 

Thanx,