How do you make that last connection to Septic tank opening?

You will need some tar sealant.

1. Insert the pipe into the inlet opening of the tank until the pipe sticks in about 2 inches. Locate the pipe far enough into the tank that incoming waste water does not follow the tank wall down but free-falls out of the pipe. The pipe must be at least 6 inches from the baffle (which is in the center of the tank), to prevent clogs from forming.

2. Heat the tar sealant in direct sunlight for 15 minutes.

3. Clean the void between the newly installed pipe and the septic tank concrete with a wire brush to remove any debris.

4. Fill the void between the pipe and the concrete with the tar sealant. Press the sealant into the void with a trowel. If the septic tank has a rubber gasket molded into the tank for the pipe, tighten down on the securing clamp.

We got this all done, infiltrator panels & a 750 gallon polly tank that is level. The only problem is it slowly leaks at the inlet since the tank is level but the line slopes slightly. What is the trick on that last connection to make sure it seals properly at the inlet?

pull the rubber boot that's on the septic tank out and use a big hose clamp to clamp the drain pipe to it.