Distilled Water

[Stasiak]

Hello,

I have a question about distilled water.

I read that using distilled water and then adding shrimp minerals to it to bring the minerals back up is a good way to lower the PH.

So I went out and bought bottled distilled water. I tested it, and the ph was 6.0. I added the minerals and then let it sit for 1 hr. I tested the water again. The GH was at the high end for cherries, and the PH was about 8.2. I figured I added too much minerals.

I had another bottle of of distilled water. I tested it when I opened that one. It was 6.0. I added the minerals. Only a little dash. I let it sit. 1 hour latter, tested the water. Barely a trace of gh and kh but the ph was 8.0. 

So, my question is. Does the ph of bottle still water go up after you open it and then come back down? Do I have to leave it sit before it comes down? 

Thank you very much for any help you may have to offer.

[NoGi]

What minerals are you adding? And are you adding to the bottle or pouring into tank first?

[fishmosy]

If the bottle has been shaken at any point before you measure pH, CO2 will have dissolved into the water (forming a weak acid) and lowering pH. This happens because there are no minerals in distilled water to buffer against the acid created by the CO2. When you add minerals, this bufffers up the pH, hence why the pH rose dramatically after you added them. Likewise some of the CO2 would have gassed off, getting rid of the acid it creates when it dissolves in water. 

[Stasiak]

What minerals are you adding? And are you adding to the bottle or pouring into tank first?

Hello.  It was a 1 gallon bottle of distilled water.  The minerals I added to it were SaltyShrimp Shrimp minerals. 

If the bottle has been shaken at any point before you measure pH, CO2 will have dissolved into the water (forming a weak acid) and lowering pH. This happens because there are no minerals in distilled water to buffer against the acid created by the CO2. When you add minerals, this bufffers up the pH, hence why the pH rose dramatically after you added them. Likewise some of the CO2 would have gassed off, getting rid of the acid it creates when it dissolves in water. 

So would the PH go back to around 7 or just stay elevated? 

Also, sorry I didn't replay back sooner.  I thought I was getting email notifications when somebody posted back to me. 

[fishmosy]

The pH of RO water will stay elevated once you add minerals. pH though is unimportant because the pH of the water in your tank will regulate the pH of the mineralised RO water that you add. More important is that you add a consistent amount of mineral to match the amount of minerals in your tank already. You can ensure this by mixing your RO and minerals to a specific TDS.