Quesions About Ta Vs Ph

[kincade]

First of all, thanks for all the help you have all given me so far. I have been using the dichlor/bleach/nitro method for a few months now and it seems to be working perfectly, albeit slightly more time consuming than I would like.

I have learned that during the dichlor phase, I will want a TA of around 80. When I switch to bleach, I will want a TA closer to 60 ppm. This worked to keep my PH between 7.6 and 7.8 without any corrections.

I'm wondering what the TA should be for those that use the Nature 2/MPS method? I'd like to try it for a bit and see how it compares to the dichlor bleach method.

Secondly, I'm wondering what MPS, bleach, and Dichlor do to the PH? Do they all raise the ph slightly?

Thanks for any help you can give!

[chem geek]

There isn't any single correct TA level since every situation is different. The basic rule is to have a TA such that the pH is fairly stable. If the pH tends to rise, then the TA should probably be lowered; if the pH tends to fall, then the TA should probably be raised (up to a point). At any rate, you found some "sweet spots" for TA in your situation.

With MPS you will want the TA higher, so you can try 80 to start with and see how that goes. Some MPS products are more pH balanced than others, but all are acidic to some extent. Dichlor is also net acidic because though it is fairly pH neutral upon addition, the consumption/usage of chlorine is acidic so the net result from using Dichlor is a drop in pH over time. A higher TA compensates for this and with a high enough TA you can have the pH be fairly stable and instead see a slow drop in TA over time. The same is true when using MPS.

Bleach raises the pH upon addition, but then chlorine usage/consumption lowers the pH with the net result being close to pH neutral. There is a small rise in pH over time from the excess lye in bleach -- 6% Clorox Regular unscented bleach is the best because it's pH is 11.9 and has the lowest amount of excess lye. Any higher rise in pH over time is due to carbon dioxide outgassing from the TA so a lower TA reduces that.