PH and is it's effect on salt mixes.

[Flippers4pups]

In my quest to find answers, most reef salt companies will state in their instructions for proper mixing of their salts, to use 0 TDS RO/DI water with a temperature range from 70ish to mid 70's in a mixing container.

Also,
They say to mix salt into the water, not the other way around and to slowly add salt to the water. Most salt mixes will dissolve at different rates and may not totally become clear for several hours.

Okay on to the meat of what i don't see. I don't see anything on PH of the RO/DI water prior to adding the salt. True pure water will have a neutral value. In other words a PH of 7 and any effect of temperature increase shouldn't effect its PH.

But true RO/DI water isn't 100% pure water and i'm assuming that is why they recommend the temperature range, but ph isn't the only reason why, it's to ensure proper mixing of the elements in the salt mix.

So does RO/DI water Ph have an effect on how salt mixes dissolve and become more soluble?

@Randy Holmes-Farley

 

[Randy Holmes-Farley]

There is zero concern about the pH of 0-1 ppm TDS water. It will generally be lower than 7 due to CO2 (even if it falsely or even really reads higher; mine read high, but Ro/DI pH is not correctly read by ordinary pH meters), but that is insignificant compared to the buffering of the seawater, and aeration/mixing of the salt water will equilibrate CO2 and might pull in more anyway.

 

[Flippers4pups]

There is zero concern about the pH of 0-1 ppm TDS water. It will generally be lower than 7 due to CO2 (even if it falsely or even really reads higher; mine read high, but Ro/DI pH is not correctly read by ordinary pH meters), but that is insignificant compared to the buffering of the seawater, and aeration/mixing of the salt water will equilibrate CO2 and might pull in more anyway.

Thanks for the response Randy. I pointed this question in this direction because of the increasing number of hobbyists experiencing fouling/caking in their mixing container.

 

[Randy Holmes-Farley]

As an aside, adding totally pure fresh water at pH 7.0 to reef tank water at pH 8.2 will actually raise the pH of the water above 8.2!!!

 

[Randy Holmes-Farley]

Thanks for the response Randy. I pointed this question in this direction because of the increasing number of hobbyists experiencing fouling/caking in their mixing container.

That is likely due to the high alkalinity in some salt mixes.

 

[Flippers4pups]

That is likely due to the high alkalinity in some salt mixes.

I agree. But is there a method to somehow mitigate this? Not post, before?

 

[Randy Holmes-Farley]

I agree. But is there a method to somehow mitigate this? Not post, before?

Depends on how much you care to do. Using cold water and adding salt to water with rapid mixing in high CO2 air will minimize the effect. Adding acid to lower the alk eliminates the concern (Some add muriatic acid to IO and see zero precipitate).

One could also add organic matter and phosphate to prevent precipitation. Polyacrylic acid works very well.