Graduating from construction to management - initial fill test results

[bdrums]

Initial fill completed this morning. Decided to test pH, TA and CH to see what we're starting with.

pH >= 8.2
CH = 75
TA = 330

Now, we have what we would consider hard water here north of Houston so I was kinda surprised to see the CH test turn blue after only 3 drops. I suppose this is a good problem to have if you have to have a problem with CH in the fill water.

I was also surprised at the pH number, but not overly so.

The TA number is the one I'm most concerned with. Before I run through another test (and use 33 more drops of reagent), I wanted to post this and see what others have to say. Especially those around me.

My testing methodology: I followed the instructions on the laminated card. Meaning I didn't review the extended test kit directions posted in the other forum. This was my very first trial with the test kit.

I bought extra magnets and extra 40 ml vials from TFP Test Kits so I could dedicate a vial and magnet to each test.
We had an old BBQ sauce plastic bottle from a local restaurant. Rinsed it out with warm water and Dawn several times.
Used a 1/2" x 36" PVC pipe (with cap with hole on one end and fitting with 3/8" ID tubing on the draw end) to extract water from below the surface of the pool.
Rinsed all bottles and magnets to be used for tests with pool water.

For TA, I made sure to wipe the tip with a damp paper towel. Didn't use a cloth as instructed by the kit. Can't believe that would make a huge difference, but I'm certainly open to being wrong.

Thoughts?

 

[JoyfulNoise]

Is the fill water from a well or municipal?

It is not uncommon in some parts of the country for deep well water to be highly alkaline especially if the aquifer has a lot of limestone around it. What you're seeing there is very high carbonate alkalinity. To reduce it, you're going to have to use the acid-aeration process. It will take a lot of acid and a lot of time to get it down.

If your fill water is that high, then you're going to need to manage your evaporation rate for the pool water or else you'll always be fighting high TA and rising pH. A good bubble cover will help a lot in that cause.


Sent from my iPhone using Tapatalk

 

[bdrums]

We're on city water. Knowing that, do the numbers surprise you or within the realm of possibility? Should I test again? Anything I should change in the methodology?

Thanks, Matt.

 

[bdavis466]

I'm more surprised the CH is as low as it is.

Be prepared to go through tons of acid in attempts to not only lower the TA but also maintain it. Limiting evaporation will be extremely beneficial.

I used about a gallon of acid per day with a TA of 375 and fresh plaster, and that was just to maintain a pH of 7.8 in 33K gallons. If you haven't already, consider a bicarbonate startup since you are nearly there anyway. Might as well take advantage of your fill water.

 

[JoyfulNoise]

Guess they don't pay those guys too much at the water treatment plant

It's funny because I have the opposite problem from you (worse I think) - my pH is typically 8.0, CH is 280ppm on a good day but my TA is only 90-110ppm. So I've got fairly low pool TA but I'm always suffering from high CH.

Your testing seems fine to me. Although you might want to use the lower resolution test on your TA until you get it down. I still recommend using acid/aeration to get your TA down. Just remember that muriatic acid adds chloride to your water, so every gallon of MA you use will add about 33ppm chloride (as measured in NaCl weight).


Sent from my iPhone using Tapatalk

 

[bdavis466]

Just remember that muriatic acid adds chloride to your water, so every gallon of MA you use will add about 33ppm chloride (as measured in NaCl weight).


Sent from my iPhone using Tapatalk

I'm glad to see you sharing this with people. The chloride content of acid was always dismissed as being minuscule.

 

[bdrums]

I'm more surprised the CH is as low as it is.

I was pretty surprised, too. I'll test again tomorrow. It turned a light blue after 3 drops so I stopped. Does it need to turn darker blue?

Be prepared to go through tons of acid in attempts to not only lower the TA but also maintain it. Limiting evaporation will be extremely beneficial.

I get it, but I just don't see us doing that. People at home during the day - I suspect we'll use it quite a bit so I can't really see us covering it.

If you haven't already, consider a bicarbonate startup since you are nearly there anyway. Might as well take advantage of your fill water.

I think I'm at the mercy of the PB.

Thanks for your insight.

- - - Updated - - -

Your testing seems fine to me. Although you might want to use the lower resolution test on your TA until you get it down. I still recommend using acid/aeration to get your TA down.

OK, thanks. I'll check on the lower rez test. Right now PB hasn't started up the pumps so I'm getting no flow at the moment.

 

[bdavis466]

I'm with you on the pool cover. I desperately need one but I refuse to give up my view...maybe once someone can make an invisible cover that actually works!

 

[Divin Dave]

You need to keep adding drops until there is no more change in the color at all. When you have added the last drop and there isn't any change, then don't count the last drop.

It turned a light blue after 3 drops so I stopped. Does it need to turn darker blue?

 

[bdrums]

Thanks Dave. Might need to update the instructions provided with the kit. I double checked the laminated card and it, indeed, says "until the color changes to blue."

 

[bdrums]

Found this link that shows average water hardness and alkalinity across the US. Seems like it matches my initial results. We have low hardness (not the softest) and very high alkalinity in the Houston area.

http://water.usgs.gov/owq/hardness-alkalinity.html

 

[bdrums]

This is odd to me. I'm not aware of a water softener in our house. When I test the fill water, I routinely get 50 - 75 for the CH. When I test the pool water I get 300 +/- 25.

Our PB measured CH as 280.

I tested both the outside tap and the cold water at the sink in the kitchen.

 

[JoyfulNoise]

This is odd to me. I'm not aware of a water softener in our house. When I test the fill water, I routinely get 50 - 75 for the CH. When I test the pool water I get 300 +/- 25.

Our PB measured CH as 280.

I tested both the outside tap and the cold water at the sink in the kitchen.

You mean your inside faucet is 50-75ppm and your outside spigot is 300ppm?


Sent from my iPhone using Tapatalk

 

[bdrums]

Sorry. Wasn't clear. No. The pool water is 300. The outside spigot and inside faucet yield 50-75.

Granted, the PB added some chemicals at startup. I don't know exactly what he added. My mention of the pool water is to show that I and the PB get similar results and that those results differ greatly from the fill water.

I would have expected our fill water to contain more calcium, but maybe not. It certainly doesn't feel soft.

 

[JoyfulNoise]

Sounds normal to me.

Your tap water would be considered too aggressive for a plaster fill. Depending on the startup process used, your fill water would require adding calcium chloride to a minimum level of 200ppm to keep the water from etching new plaster. So I'm not at all surprised if your PB added calcium. Take that with evaporation and fill water hardness as well as the calcium that gets ejected from the plaster during curing, and I can easily see your water hitting 350ppm.

Municipal fill water can fluctuate in CH too. So there may be times of the year when it registers more CH than others. But the fluctuation should be minimal.


Sent from my iPhone using Tapatalk