Pool Numbers Check

[Miniduper]

Hi All,

I've been managing a 1700 Gallon Intex Pool this summer. Currently using a Intex Sand Filter with a Intex SWG which constantly scales up every couple days and displays High Salt Alarms. Vinegar uses fixes that for a few days.

Test Kit Taylor K-2006C
FC 3.0
Cya 55
pH 7.2
TA 175 -200
CA 350
Salt 2120

Questions

1.) Any recommendations?
2.) My house tap water (no softener) is 250 PPM yet my pool is 350? Is that normal for the pool water to get harder?
3.) If I have to keep adding fresh water weekly, how should I expect that to effect the numbers?

Thanks

 

[mknauss]

As the water in the pool evaporates, it leave the calcium behind. You add high TA and CH fill water, and those values go up.
The SWCG is scaling because of the high TA. If you agressively lower that, the scaling will reduce. It might be easier to dump the water and start over as your fill water TA is 130 ppm.

Technically you are fine on FC. I would suggest a higher level for a small pool. Two children in that pool volume could force the FC to 0 quickly.

 

[Miniduper]

Totally makes sense, thanks for clear explanation

 

[Richard320]

My surface to volume ratio is lower than yours and I lose enough to evaporation that my CH rises about 25/week in the summer. I'd say your numbers are normal. Work on getting the TA down. That will reduce the CSI and reduce the SWG scaling. Plug your numbers into poolmath and play with them. You'll see what affects the CSI number. You can't do much about CH or water temperature. pH has a limited range if you want it to be swimmer-friendly. That leaves you with TA as the parameter you can manipulate.

 

[Miniduper]

Does my SWG connected to the return hose, aerate the pool? I'm going to assume no since my TA never seems to go down with the current setup.

 

[Richard320]

Does my SWG connected to the return hose, aerate the pool? I'm going to assume no since my TA never seems to go down with the current setup.

Not so you'd notice.

Anything that looks like a shower head or a sprinkler that stirs up the surface will aerate. It will also cool the water some with increased evaporation. But it also raises CH slightly with evaporation. If you can point it up so it breaks the surface it might help. For that matter, a leaf blower or the return side of a shop vacuum blowing bubbles in the pool will aerate. So will a couple kids with kickboards.

 

[Miniduper]

Yesterday I used Muriatic acid In attempt to lower my TA, however I woke this morning to much of the same numbers.

Last Night's Numbers (Test Kit Taylor K-2006C )

FC 0 (SWG was scaled up while I was out of town so I had to clean with vinegar)
pH 7.8 - 8.0
TA 210

Added 1 Cup of Muriatic Acid (Hydrogen Chloride 14.50%) in front of the return
PoolMath said to use 2 Cups to go from 7.8 to 7.2 pH but I decided to ease my way there

Ran Filter and SWG for 12 Hours overnight

This morning here are the numbers

FC 4.6
pH 7.8
TA 210

Before I go adding more looking for advice. Am I missing something here? Thanks

 

[mknauss]

You are not missing anything. Your TA is elevated. Your fill water TA is 130 ppm so when you add water due to evaporation your TA goes up. The pH rises due to any minor aeration effect with an elevated TA. I would suggest you test your pH every day, lower it to 7.2, every day, and test your TA at least every other day. Splashing is a great way to aerate so if the pool is used every day, your pH will rise, every day.

 

[Richard320]

Hmm, when I punch in the numbers, 1700 gallons and 210 TA, it says it wants 26 ounces of 14.5% acid to go from 7.8 to 7.2. You're sort of iffy on the starting pH.... is it 7.8 or 8.0 or somewhere in between? And recall that pH is logarithmic, so the jumps between each measurement are not identical. Think CYA view tube. Because to drop from 8 to 7.2 wants 33 ounces.

So you underdosed with 25 to 33% of what was needed. I'm not surprised you didn't get the result you wanted.

Also, 8 ounces of weak acid will only reduce the TA by 8 or 9. That's less than one drop out of 21, which is well within the margin of error.

 

[Dirk]

I solved my high CH fill water dilemma by replumbing my pool's auto-filler to my home's water softener. I haven't had to replace water yet, and my CH has been very stable for a few years now at 350 (I have a plaster pool). I like the soft water inside the house too, as it has solved the other problems associated with hard water (wearing out fixtures, messing with the toilet bowls, scale on shower glass doors, etc). I also have a whole house water filter, so my pool fill water is now both soft and clean!

I don't think a softener will help with TA, but it could solve for half the problem, and you'll be able to lather up properly in the bath, too!

 

[Miniduper]

Hmm, when I punch in the numbers, 1700 gallons and 210 TA, it says it wants 26 ounces of 14.5% acid to go from 7.8 to 7.2. You're sort of iffy on the starting pH.... is it 7.8 or 8.0 or somewhere in between? And recall that pH is logarithmic, so the jumps between each measurement are not identical. Think CYA view tube. Because to drop from 8 to 7.2 wants 33 ounces.

So you underdosed with 25 to 33% of what was needed. I'm not surprised you didn't get the result you wanted.

Also, 8 ounces of weak acid will only reduce the TA by 8 or 9. That's less than one drop out of 21, which is well within the margin of error.

I'm not getting those same calculations. I've attached a screenshot of my calculations. Based on this says 18 oz (or about 2 cups). Reason I said 7.8 - 8.0 because I couldn't really tell the color difference and those looked almost the same to me. I really want to get the numbers right before I go adding the Muriatic acid again. Thanks

 

[Richard320]

I'm not getting those same calculations. I've attached a screenshot of my calculations. Based on this says 18 oz (or about 2 cups). Reason I said 7.8 - 8.0 because I couldn't really tell the color difference and those looked almost the same to me. I really want to get the numbers right before I go adding the Muriatic acid again. Thanks

I see my mistake. Mine still had 50 borates stored from the last time I messed with things. Once I zeroed that I got 18 oz as well. Anyway, you still added less than half of what was called for. And the TA reduction is still as small, so the pH will pop back up again.