Plumbing

Some time ago there was an article here about Melev's new salt water mixing barrel he built. I was quite impressed by it and am now considering something like it. However, I can no longer find the article. I would appreciate any help that can be provided.As for me I haven't posted in a while...recently bought a new house with a office (fish-room) that I am outfitting with a 75 g reef tank, 40 g sump, 10 g gravity ATO and finally a 20 g refugium (last).I picked up a 55 gal food-quality barrel ...

Building my 20 gal long sump from vague plans found on the internet and answered questions from here. Thanks Melev. I am about ready to plumb and saw the writing about drilling two holes in the return line to create a siphon break in case of power outage. Where exactly does that go? I thought it said about X inches below the water line but that doesn't make sense to me. Please answer and explain. Thx