Split off of Pool turned cloudy overnight. This question was off topic for that thread. JasonLion
i'm still curious of why the TA is being kept so low?Originally Posted by Mr. Ed
Having a lower TA can help slow the rise of pH. High TA = high dissolved CO2, which outgasses during aeration leading to pH rise. Having a lower TA means less CO2 outgassing and thus a slower pH rise. 100-150 is fine for some people; other people (generally with lots of aeration and/or SWG, which is a source of aeration) experience a very fast pH rise at those levels. It just depends on the pool. Generally, people here would say don't worry about slightly high or slightly low TA, unless it causes problems (i.e. pH swings w/ really low TA and no borates; calcium scaling w/ high TA)
Originally Posted by Melt In The Sun
yes but isn't 70 a bit lower than even the typical "low" level? I don't see much relevance but it caught me by surprise.
Terry have you backwashed recently? Have you ever refreshed the Zeo as Zeo Sand suggests?
My pool likes things at a TA of 70. If it gets to 60, then I'll raise it to 80. As MITS mentioned, it really helps some of us keep from having to add so much acid. pH much more stable for me this way, not to mention that my CSI is better as well.
The different TA recommendations have to do with what you are using as the primary source of chlorine. If you are using trichlor or dichlor, they are both fairly acidic and you need a relatively high TA level to keep that from getting out of hand too quickly. In this situation TA should be at least 100, and probably higher.
If you are using bleach, a SWG, or cal-hypo, all are long term PH neutral, so you have more flexibility about where the TA level goes. If there isn't too much aeration, which I will get to in a moment, we recommend keeping TA between 70 and 90 in this situation.
One additional concern enters in when using a PH neutral chlorine source and there are significant amounts of aeration. A SWG always aerates and fountains, waterfalls, etc can also provide aeration. TA does two different things, it helps slow the rate of PH change, and it puts upward pressure on the PH (because of dissolved CO2 over saturation). When there is a source of aeration, the aeration allows the excess CO2 to outgass, and the rate of PH increase goes up. In many situations, CO2 outgassing encouraged by high TA and aeration becomes a significant factor. Targeting even lower TA levels, between 60 and 80, helps minimize this PH drift.
Ok, you all can really mess with a person’s head moving posts like this… :P I read these posts last night then came back this afternoon and poof, they’re gone. Here I am dealing with a possessed pool- and now you’ve got me questioning my sanity.
Add me to the group that finds pH stability with a low TA. Aside from the acid needed when adding borates, I’ve not added any acid in over a year. My pH is very stable.
20k white plaster with blue quartz, IntelliFlo VS, Quad DE 100
1000 gal spa with natural stone waterfall
Beach entry with 2 bubblers. Pool built Spring 2013