Recommended Calcium & Alkalinity Levels?

[AlbertSteg]

Hi -- just getting started with the TFP-Pro testing and I seem to understand the testing process ok. My question is that the recommended levels for Calcium and Total Alkalinity (Plaster Pools / SWG) seem way out of line with what I've been told by local pool maintenance store, where I've been having my water tested to date.

Budget Pools recommends:
Calcium Hardness 200-240 ppm (TFP 250 - 650)
Total Alkalinity: 80 - 120 ppm (TFP 50 - 90)

The alkalinity level is also confirmed by the values on the AquaChek test strips -- which I'm sure everybody here thinks are useless, but .... is there just a fundamental difference of view on this between TFP and these 'mainstream' sources of advice? These values don't even seem close.

Attached is a screen shot of ideal levels I found on TFP somewhere. Can anyone account for the seemingly large discrepancy in values? Is this just a case of "We know better than they do?"

 

[reggiehammond]

Pool industry uses a "calculated" alkalinity level that accounts for things other than TA. Much higher TA is necessary to maintain pools using trichlor pucks because they're so acidic.
Not sure why on calcium, but calcium, TA, pH etc all play into CSI, which is import2ant to track to avoid scale (especially with SWCG.)

Test strips are called "guess strips" for a reason.

 

[Donldson]

which I'm sure everybody here thinks has years and year of evidence indicating they are useless

FTFY

Notice how the pool store offers exactly the same advice regardless of how a pool is chlorinated? But we know the pH of the chlorine source is vastly different between an SWG or liquid chlorinated pool versus a puck chlorinated pool. Shouldn't that require some adjustments to the water chemistry to maintain a good balance?

Maybe we know better, or maybe they know as well. Either way their objective is to get you rung up and out the door and our objective is to educate you on why things are the way they are. So our answer is that the best TA is the one your pH is most stabally held in the 7's at, and with an SWG you'll be a lot more likely to find that level within our recommendations than theirs.

 

[Newdude]

Besides the chlorine addition method changing parameters such as going from pucks/trichlor to bleach and how it affects Ph, they also don't factor any regional issues.

In the east we have lots of rain to lower the CH/CYA levels and many of us find ourselves always adding some. We can be a little high and it'll fix itself. In the west, the fill water is heavy on the CH and the dry climate has them forever adding fill water which jacks the CH. They can start a bit low and the CH will quickly rise to where it needs to be. Starting low prolongs the eventual need to drain to lower the CH. Everyone in the middle, is, well, in the middle. Our ranges account for all and we custom tailor someone's plan whenever we get the chance to.

 

[AlbertSteg]

So our answer is that the best TA is the one your pH is most stabally held in the 7's at, and with an SWG you'll be a lot more likely to find that level within our recommendations than theirs.

Thanks for all the replies, I think I see what you're getting at -- so, how do I go about discovering this ideal level of TA to maintain pH in the 7's? I'm using the
'Pool Math' app, but so far I haven't been able to locate the part that recommends how to address the chemical imbalances by adding various chemicals -- is there a feature or reference page I'm missing?

 

[Donldson]

how do I go about discovering this ideal level of TA to maintain pH in the 7's?

Just maintain your pH. As it rises you'll use acid to reduce it, which will drop the TA level as well. As your TA drops the frequency of needing to add acid will drop until eventually your pH is mostly stable. That will be your ideal level.

PoolMath is a good tool, but it's still just a tool. Most of the actual education happens on the forum. Some of the more barebones basics can be found here: Pool Care Basics And for more in depth information on a lot of what we talk about we have our Wiki

 

[AlbertSteg]

Oh, that makes sense -- thanks for sending the link to the WIKI -- I hadn't stumbled across it yet and looks really useful. Will "dive" in, har.