My toilet flapper will not stay open long enough for the water to come out of the tank, so the toilet does not get flushed all the way. I have adjusted the chain and that does nothing.
Also the water level has to be below the water level line, or the water that is in the tank will slowly flow into the tube that is connected to the flapper and just makes a constant water running sound.
I just don't know what to do.

So the water level has to be well below the water level line in order to keep it from flowing in the tube, but I still have a problem with the flapper not staying open. Also the water flows into the tank much slower than say my other tank, but my other tank is newer. This tank is old. The flapper is probably just under a year old. It is a universal flapper... it is a korky flapper with yellow float.