Pool store madness and question about Total Alkalinity

[glenwill]

First the Pool Store story:

My neighbor just got an in ground pool built, and I've been suggesting him to follow the TFP approach, get a good test kit, and learn how to maintain chemistry. I suggested an SWG, as I've been very happy with mine.

About a week after his start up, I went over to check it out, and he had chlorine pucks in his skimmer. He said the pool store told him that even with the SWG, he still needed to put chlorine (Trichlor) into the skimmer! I got my test kit, and his chlorine was 16.5! His CYA is 70, so 16.5 chlorine is over triple the recommended level. He shut off his SWG for a few days, and brought it down.

My question is about Total Alkalinity level. He has an Eco Finish Aqua Bright pool surface:
http://www.ecopoolfinish.com/aquabright/

Their startup/maintenance guide recommends TA 120-150. This is a lot higher than I've ever seen recommended, and I wanted to know if anyone has experience with this, and knows if this makes sense. Will TA that high cause any other problems?

Startup guide

Glen

 

[JoyfulNoise]

For new plaster you want the TA to be a bit higher since the plaster uses the dissolved CO2 and H2O in the pool water to cure (calcium oxide in the plaster converts to calcium carbonate). So having excess carbonate helps with the curing process. Typically after the first month, you can then lower the TA to levels recommended here. Also, when you start plaster, you usually don't add salt or use the SWG until after the first month.

However, your friend is using trichlor which is very acidic and lowers the TA so it's not helping him maintain the alkalinity.


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[chem geek]

For an SWG, the recommended CYA level will be 60-80 with 80 ppm preferred in a hot sunny area. So that part isn't as bad as it sounds (i.e. not triple the recommended level). Of course, the salt probably hasn't been added so the SWG isn't on yet so in the interim with manual dosing it would have been better to have the CYA lower. By "recommended level" did you mean what the PB said the CYA should be during plaster startup/curing?

 

[glenwill]

For an SWG, the recommended CYA level will be 60-80 with 80 ppm preferred in a hot sunny area. So that part isn't as bad as it sounds (i.e. not triple the recommended level).

Thanks. I meant the chlorine level of 16.5. And why would they tell him to put chlorine pucks weekly in an SWG pool? I can see why you were confused, as my wording was confusing. I was saying that at a CYA level of 70, a chlorine level of 16.5 is triple the recommended level.

- - - Updated - - -

For new plaster you want the TA to be a bit higher since the plaster uses the dissolved CO2 and H2O in the pool water to cure (calcium oxide in the plaster converts to calcium carbonate). So having excess carbonate helps with the curing process. Typically after the first month, you can then lower the TA to levels recommended here. Also, when you start plaster, you usually don't add salt or use the SWG until after the first month.

However, your friend is using trichlor which is very acidic and lowers the TA so it's not helping him maintain the alkalinity.


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Thanks for replying. I don't know if you are familiar with Aqua Bright, but it's not plaster. The links I included explain how it works. It's like a melted-on plastic coating, applied with torches. The result is smooth like a vinyl liner. The company advertises that it doesn't need the startup chemical balance, and can be set to maintenance levels immediately and swim as soon as it's balanced.

The Aqua Bright company recommends 120-150 TA as an ongoing level, not a startup level. That seems high to me.

 

[chem geek]

Because they don't know any better. If they had started the CYA much lower, then the Trichlor would have been OK because 1) it would build up the CYA level and 2) it's acidic which is needed during curing when the pH will rise. So they don't foul up that much except by starting out with too high a CYA level to begin with. They should have just had the pucks in a floater and not put them in the skimmer. They might have been worried about the floater getting close to the plaster and harming that section, but the floater could be tethered or held somewhere away from the edges.

 

[JoyfulNoise]

Thanks. I had not heard of AquaBright. Interesting product but I prefer my eeeevil masonry finish with all of its startup problems you just gotta love sales literature.

I was in an old indoor pool once where they had chipped away the old plaster and recoated with a thick rubberized paint (because it was the cheapest thing to do). I have to say I really did not like the look or feel of it. Perhaps this AquaBright stuff is better.

Thanks for the education, I learn something new everyday here on TFP.


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