Freshly mixed SW question.

[phenom5]

Whenever I mix up SW for a water change, I let it circulate for a day or two before I use it. From what I understand, with newly mixed SW, the synthetic salt mix causes some of the parameters to go haywire. My question is, which of the parameters are those, and what do they do.

This is really just a question that I have out of curiousity.

Thanks.

[Randy Holmes-Farley]

I'm not sure what you mean about parameters going haywire. As soon as the salt dissolves, it has all the calcium and alkalinity and magnesium it will ever have. pH may take a little time to stabilize as CO2 is pulled in or expelled from the solution, but it many cases it too is stable from the start.

[phenom5]

Okay...

As far as the parameters going haywire, that's what I've always been told.

So my next question would be, why is it recommended that you let the water circulate/ aerate for a minimum of 24 hrs.?

[bertoni]

Once all the crystals have dissolved, the salt might be ready to go. Just check the pH and make sure that it's acceptable. The pH can change drastically, depending on the brand of salt in use. I think that 24 hours is usually overkill, but it won't hurt.

[phenom5]

Interesting.

So, if I mix my saltwater really well, and make sure the pH is stable, it should be ready to use after a few hours?

Very interesting.

[bertoni]

Yes, that's usually fine.

[phenom5]

I guess that 24 hr thing is one of those reef myths perpetuated by people who read something, somewhere, and dutifully passed it along as fact. (myself included :D )

Thanks.

[Mark426]

I mix mine and as soon as I can get the temp to match my tank...in it goes. 20% water change every week for 2 yrs and no problems at all. As a matter of fact, my corals look their best shortly after a water change. The whole process takes 15-20 minutes, a little longer if the water was really cold when I mixed it.

Mark

p.s. Over on another site I visit, there is a Chemist who works in a very large lab (think it’s Dow Chemical) that wondered the same thing. He did an incredible amount chemical analysis and found virtually no difference between water that had been mixed for less than 1 hour vs. water that was mixed for over 24 hours. Take that for what its worth.

[Randy Holmes-Farley]

I guess that 24 hr thing is one of those reef myths perpetuated by people who read something, somewhere, and dutifully passed it along as fact.

Many mixes have (or historically have had) pH values far from equilibrium, and one good reason to aerate for 24 h was to bring it in line, as I mentioned above. Some initially mixed to pH above 8.5, and without aeration would not be suitable. Bringing in CO2 is often a slow process, and it can take more than a little aeration.