If you want to use something to cut water, stick to natural diuretics like dandelion root which is safe. Also cut sodium and carbs and that will reduce your weight once you are depleted. Start water loading right now, 2 gallons per day minimum and then cut water completeky at least 12 hours before the meet. That alone can dry you out big time.
Being a competitive bodybuilder and former competitive wrestler, I know a few tricks of the trade lol
You just want to avoid these hardcore prescription diuretics....especially as a competitive athlete. They are very dangerous and can put you in the hospital if you get your electrolyte balance off. Most are not potassium sparing and will give you crippling cramps that will keep you from being able to perform at the level you need to be at. Even worse it can dehydrate you so bad you can collapse and go to the hospital.