his might seem simple but can save your self some money long term. I suggest prime/safe when you declore your water. You might pay a little more per oz but a little goes a long ways. Safe which is the dry forum of prime can save you even more and not very hard to dose.

Directions: Use 1 capful (5 mL) for each 200 L (50 gallons*) of new water. This removes approximately 1 mg/L ammonia, 4 mg/L chloramine, or 5 mg/L chlorine. For smaller doses, please note each cap thread is approx. 1 mL. May be added to aquarium directly, but better if added to new water first. If adding directly to aquarium, base dose on aquarium volume. Sulfur odor is normal. For exceptionally high chloramine concentrations, a double dose may be used safely. To detoxify nitrite in an emergency, up to 5 times normal dose may be used. If temperature is > 30 °C (86 °F) and chlorine or ammonia levels are low, use a half dose.

Typically other products take 1 capful per 10 gallons. I have bought the 2L bottles in the past. Even with all my tanks it seems to last forever.