I did a leak test on a new holding tank today. The sender and inlet were fine. The inspection plate had a drip after a few hours, but the vent and outlet did not seal. Both are 90s, so they need to be a specific orientation. Ronco says the fittings should dry seal and I've read if they don't you can use some Teflon tape which I did with no difference. What am I don't wrong? Is there something better then Teflon tape I can use or is there a specific brand of fitting I should use? I really don't want to get this one wrong for obvious reasons.