I love all of the API products, especially their easy to use test kits. This product is great as well. Regardless of which size you buy of their tap water conditioner, it is the best value of reputable brands that will treat all tap water for your pond or tank. It only requires 3 drops per gallon you add to your tank. It removes chlorine, neutralizes chloramines, and helps detoxify any heavy metals in your tap water. Some more expensive products will claim to also include things to help your fish maintain their protective slime coating (and cure male pattern baldness and perhaps ED). If your fish are healthy, and your tank's water parameters are maintained well through weekly water changes and good filtration, those other ingredients are useless. (The "Special Sauce" is just ketchup, mayonnaise, and relish.) If your fish have sores or other health problems, then find the cause, fix it, and treat them with something besides a tap water conditioner if needed. Like every other tap water treatment API's instructions first tell you an amount of the product required to remove chlorine, and then in smaller print below say to use 2 to 3 times as much to also neutralize the more toxic chloramines that may be added during the purification of your water. I don't know why the companies that make these products won't be honest and say up front to use the higher amount, and then in small print say you can skimp and use less if you want to save money and risk the health of your fish. If you have confirmed with your local water authority that they do not use chloramines during their treatment or your water, then it only requires a single drop per gallon to remove chlorine. I did not bother to call my county water authority, since I had no way to confirm that the person who answered the phone would know chlorine, chloramine, nor chloroform for that matter. from their own colon or a hole in the ground. Even if you personally spoke to someone that could tell you for dead certain that chloramines are not being used, they are not going to text you if that changes in the future. Unless you are the person in charge of that step of water treatment for your area, the only way to know for certain if your water was safe for your fish with only a single drop per gallon, is if you use one drop, then test that water for any detectable ammonia that is the treated water. The chloramines contain a small amount of ammonia. Then you would know it was safe to add to your tank without causing them irritation and inflammation of their gill tissue. It is much safer to simply to add 3 drops per gallon. More doesn't hurt anything, but it's just wasted. To refill my tanks, I keep a pair of 5 gallon plastic bottles that were used for filtered / spring water. After I fill my tanks, I add the tap water treatment to the jug, refill it, and let it sit until I need it. This allows the conditioner time for its anti-heavy metal ingredients to work fully. It also lets the water come to room temperature, since 5 gallons of icy cold tap water in winter can cause the temp to drop in a 55 gallon tank. Perhaps more importantly, the water lines in many places are old and require frequent repairs or expansion. When repairs are made to water mains, they sometimes add extra chlorine disinfectant at the repair site to insure that any bacteria that might have gotten introduced to the main are killed and cannot grow and contaminate our drinking water. While I cannot normally detect a smell of chlorine in my tap water, I occasionally notice that it smells a bit more like a swimming pool than tap water. If more chlorine than normal is in the tap water, then more neutralizer would be needed. Most Chlorine will gas off on its own if the tap water is left uncovered for 24 hours, but Chloramine will not. When they disinfect a repair site, they are normally only using chlorine. By leaving the water I will add to my tank sitting for at least a day, then I am positive that it is always safe to add to my tank. I have had people ask me before if they can add the conditioner to the tank and then use a water hose to refill their tank. I don't normally recommend this because many of our fish are conditioned to come to the part of the tank where we are standing and adding water, because they think food will soon be added as well. If you add the conditioner to the tanks water rather than to the tap water first, then the tap water from a hose will take a short while to react with the treatment additive. Temporary short spikes of chlorine won't kill your fish, but cumulatively over time, it's not good for them either. Also unless you have a hose that is certified safe for drinking from, it can leach harmful chemicals into the water you're adding to the tank. If you are using a normal garden hose to refill your tank after water changes, at the minimum you should run water through it first for a few minutes to make sure that any that has been standing in the hose is washed out.