I think everyone here missed the point. First of all, you are comparing two different drugs that are not even in the same league. Arimidex will prevent estrogen-related water retention by blocking the production of estrogen in your body. You can use Arimidex for as long as you are taking test, and it works great. The only downside of taking Arimidex is that you may experience cholesterol-related side effects since estrogen regulates cholesterol levels in the blood.
I prefer the pill form of Arimidex since after using the liquid form I did not get the same great results as I did from the pills.
Lasix is purely a diuretic that is used a few days before a competition. I recently tried Lasix, just for the fuck of it, and it made me piss my brains out for about 5 straight hours just from taking a single pill. It was very inconvenient to say the least. Unlike Arimidex, you can take Lasix for only a few days because it will deplete potassium and sodium levels from your body, which will leave your muscles looking soft and flat.
Hope it helps,
SAF