Ph of ATO water

RAZ · Dec 19, 2013

Hello everyone, I've wondered for a long time about this: do I have to adjust the Ph of the water I'm using for the ATO? I've already asked that to a person here in Brazil, but he only told me that he don't do it, he didn't said why, and I'd like to know that before I setup my own aquarium. In my view, if the Ph in the ATO is lower then the Ph of the tank, the Ph of the tank is gonna drop, right? Or not? So if you guys could tell me what you do, and WHY, I'd appreciate very much.

Thanks in advance for the answers,

Rafael Zambon

mcarroll · Dec 19, 2013

The whole idea of RODI water is that it's adds nothing to your seawater that would alter its mineral content.

Also due do it's lack of mineral content, it really doesn't have a pH either. Or put another way, the first thing it dissolves (co2 from air, anything...water is the ultimate solvent) will more or less dictate its pH.

-Matt

redfishbluefish · Dec 19, 2013

Matt, above more or less mentioned it…..pure water has no buffering capability (that is, ability to hold a particular pH). The first “buffer” it comes into contact with will determine it’s pH. The actual pH of pure water is 7….but as Matt pointed out, it you look at it cross-eyed (or expose it to CO2, as example), it won’t be 7. Bottom line, leave you ATO water alone.

AZDesertRat · Dec 19, 2013

You cannot accurately measure the pH of ultrapure water, there are too few ions to measure. With normal topoff amounts you should not see any change in the pH of the tank. Consider it to be neutral.

redfishbluefish · Dec 19, 2013

AZDesertRat said:
You cannot accurately measure the pH of ultrapure water, there are too few ions to measure. With normal topoff amounts you should not see any change in the pH of the tank. Consider it to be neutral.

??? There are plenty of ions present.....hydrogen ions.....pH is actually - log [H]....in English, that is the negative log of the hydrogen ion concentration. For the sake of this argument, a pH of 7...or better yet, neutral. Again, what is critical in understanding water is that it has no buffering capability. The pH will quickly change to whatever solution it is being added to. In this particular case, when your ATO pumps water into the DT, it will immediately be brought to the current pH of the tank.