TA question with a SWG (from PS material)

[shep377]

I am currently enrolled in pool school. Hopefully in a month or so I can be well on my way to running BBB trouble free. I came across something I didn't understand while reading about the TA levels in PS.

Taken from Water Balance for SWGs:

Adjust your Total Alkalinity to 60-80 ppm. (This is IMPORTANT!)

But also, taken from Lower Total Alkalinity:

You shouldn't lower TA just to reach a target number. Make sure you actually have one of the above issues before lowering your TA.

If it is IMPORTANT to have your TA between 60-80 for a SWG then why is it not important to just lower to reach a target? Armed with my cruddy kit (until I pickup my TF100 parcel tomorrow) my TA is ~190 and pH is 7.2. Other readings to follow, but I just like to try and understand the concepts in Pool School.

Thanks for clarification!

 

[JasonLion]

If you don't have any aeration, TA can be fairly high without causing any problems. However, a SWG aerates the water, so the PH will go up when TA is high and you have a SWG. Nominally, you should wait until you actually have a problem with the PH going up, which is what the instructions are trying to tell you. I expect you will have some fairly rapid PH increase with TA at 190 and a SWG, and if you do, then you should lower TA.

 

[shep377]

OK - so I can just keep working on this, and start handling my FC (once I pickup my test kit much better!). I am struggling to try and get the SWG working properly for the first time (new pool).

I added bleach to 3ppm TC. Fell to near 0.
I started up my SWG with 8h runtime set at 50%. 2 days past.. my kit read 0.5-1.0.
Changed to 8h runtime at 65%. 2 days past.. my kit read 0.5-1.0.
Changed to 12h runtime at 80%. 2 days past... I will check tonight

The weather here has been record breaking hot and kids swimming a lot so I imagine it is falling faster then normal.
So I will just keep on the track of narrowing down my TC level and runtime/% values.

Also - what kinds of changes to people typically have to make to SWG %s through the year, hot to colder, middle summer to edges - 20% changes? Just to give me a feel for how drastic it can be.

Thanks

 

[JasonLion]

You should post a complete set of water test results. Chances are that something is out of range (most likely CYA, but there are other possibilities).