I am having trouble with a tub drain in a house that I have just moved into. The tub take about an hour to drain. I have tried drain cleaners, and they help a little for a short time but will still take 20 to 30 minutes to drain. I have tried to pulling out the drain lever on the tub witch is a rod with a spring like thing on the bottom but that does not make any difference. I do not know what else to try. The home is on a concrete slab and I have no access to the piping.