I recently built a head assembly for a drip irrigation system in our backyard. I have this adapter [1] attached to the pressure regulating filter. And I have this tubing [2] connected to the adapter.

Most of the connections between the adapter and tubing have leaks in them.
I tried sealing the leaks with a household silicone sealant (the kind used to seal around sink faucets and such) and, when that didn't work, I tried using a weatherproof silicone sealant (after cleaning away the old sealant material) but that didn't work either.

Are there any other sealants or sealing techniques anyone might recommend? Unfortunately at this point dis-assembling the connection is not a practical option.

Thank you!

[1] Adapter: https://www.amazon.com/RainBird-EFP075F-Drip-Irrigation-Adapter/dp/B0046713AE/

[2] Tubing: http://www.homedepot.com/p/Rain-Bird-1-2-in-x-500-ft-Drip-Irrigation-Tubing-Coil-T70-500S/204751462