I'd use tap water, no dechlorinator necessary. The vinegar is white distilled vinegar.. I believe its avail at Costco or most grocery stores for a couple bucks for a 1.5 gallon jug. I can't remember how much it takes to saturate the water, but I typically dump a jug in for a 55 or 75 gal tank. I'd let it sit for a while (days), depending on how much coralline is built up. You'll know when its ready because the coralline will clean off real easy. It does take some elbow grease still, occasionally.. can always add a splash more vinegar. After you're done, you can save some of the vinegar water in a 5gal bucket for future uses. (Soaking pumps, skimmers, power heads, heaters, etc). Be careful leaving pumps or power heads in there for extended periods of time though as I've heard of negative effects with the impellers.