Quite often fishing conditions dictate that a grip lead be used to hold bottom.
This normally puts a pronounced curve into the rod tip. A slack line bite
under these circumstances is very easy to spot.
When the fish picks up the
bait and runs towards the beach the rod tip lifts and at the same time the
line drops slack onto the beach. Your first job now is to reel in this slack
line until the weight of the fish is felt, even then the fish may still give
you more slack line. I tend to strike after the fish has given me slack line