Here is the post I found on chads board while back...
Bodybuilding 101: Taught by Tom Prince
Let's start with something EVERYONE should know about Lasix, but hardly anyone does. How long does lasix pull water out of your system for? (Hint: It's how the drug got it's name)
Lasix pulls water for SIX hours. Get it? LaSIX. That's important because lots of people take a lasix tab, and don't think they've pissed enough after 3 hours, so they take another tab. Problem is, the first tab will still be working for another 3 hours. So, give the lasix at LEAST 6 hours to really work, before you judge the results and take more.
Potassium: No, you don't take extra potassium. You start a minimum of 8-10 days prior to the day of the contest, and begin taking extra multi-minerals. NOT multi-vit's/multi-mins (because you'd better be already taking those), but extra MULTI-MINERALS, by theselves. Cramping occurs from a mineral IMBALANCE. That can be a lack of ANY mineral, not just potassium. Usually, it's from a lack of sodium, because most bodybuilders cut out their sodium 3-5 days before the show.
Avoid cramping: QUININE SULFATE. If you don't know what this is, you are living in the dark ages of bodybuilding. Every pro you know uses this. Welcome to the 21st century. Quinine will prevent cramping, but you have to take it BEFORE you start cramping. Meaning, if you start your Quinine on Wednesday, taking 2 tabs in the a.m., 2 in the p.m., and do that thru the day of the show, you won't cramp. Even with no sodium for 5 days, and totally dehydrated, I've never cramped when I had Quinine.
ALDACTONE: Aldactone is NOT a true diuretic. The definition of a true diuretic is that it speeds up your kidney's filtration of the blood, thus making you pee more. Aldactone does not do this. Aldactone, is a hormone blocker, that blocks the hormone "aldosterone". That's the hormone that makes you hold water. Taking aldactone, blocks that hormone, so you won't HOLD any water. Problem is, it doesn't work that well if you are already holding water.
The value of aldcatone, is that once you lose the sub-q water that is blurring your conditioning, if you're taking aldactone, that water won't spill back into the sub-q layer. BUT, you do have to get rid of that water first.
This whole thing is a very tricky process for most people, and is the single biggest pitfall that most bodybuilders fall into. 10 years later, I know people that STILL can't get it right.