• Hello guest! Are you an Apistogramma enthusiast? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's a great place for Apisto enthusiasts to meet online. Once you join you'll be able to post messages, upload pictures of your fish and tanks and have a great time with other Apisto enthusiasts. Sign up today!

Soften water with chlorhydric acid


New Member
Hi everyone! I'd like to start with apistrogrammas in my aquarium, I have a 180L tank. I live in Lima, Peru, but water in my city is very hard. TDS has a reading of 440ppm. Has anyone tried to soften water with chlorhydric acid? I know that I could use a RO system but I prefer to avoid it because of water waste.


Well-Known Member
5 Year Member
HCl will lower pH but it won't soften the water. Also, TDS is not a measure of hardness. You might have high TDS and low hardness, depending on which dissolved ions are present. Ca+ and Mg+ are the ions that create hardness.

Mike Wise

Staff member
5 Year Member
Please if you do use HCl to lower pH, DON'T add it directly to the aquarium. Mix it in a separate container first. As Gerald wrote HCl will lower pH, but not lower hardness. It will also increase your electrical conductivity.