Pool water looks great but is horribly off

lindsaygib

Active member
Jun 28, 2022
31
Las Vegas
Pool Size
14500
Surface
Plaster
Chlorine
Liquid Chlorine
A few weeks ago, before I came across this forum, we had our water tested and was told it needed to be drained but that we can’t do it until it cools(we live in Vegas and have 100+ heat right now). CYA is 120, TDS is 3000, and calcium hardness is 600. I found this forum and ordered a tf pro test kit and I’ve been adding about 1/2 gallon of 12.5% liquid chlorine a day, which I know isn’t enough. I haven’t bothered much with anything else because I know I need to get my CYA down first. So, this weekend we’re going to attempt to pull water from the top(sump pump sitting on tanning ledge) and add water to the opposite end on the bottom. Our pool water is around 85, and the tap water is cold(it’s supposed to be around 66). Overall, the water looks good, but we have an algae issue on the walls that we brush off when we see starting. After we try to take out and add water this weekend, I plan on testing the cya and hope it’s low enough. After that, get the ph down and then slam. Right? Considering the clarity of the water, should this only take a day or two for the slam? Any advice overall?
Right now I’ve been keeping my fc around 4(I know that’s too low) and my ph is 7.9, but I haven’t tried lowering it since it seems like a waste at this point.
 

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Lake Placid

Well-known member
May 27, 2021
374
St. Louis
Pool Size
17000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Hi Lindsay since no one else is taking a crack at your questions I will jump into the fray 😳. Overall I think you’ve got a handle on the direction you need to go. In looking through your water parameters that you listed I think you’d want to reverse your draw and fill locations. Draw low and fill high on the surface. The estimate is from this article: Draining - Further Reading I came up with a negative delta T using avg TDS from here Las Vegas Valley Water District 2022 Water Quality Summary

I understand why you’re not adding much FC but if you see change in water quality I‘d suggest jumping your maintenance level to around 10 ppm FC. You definitely don’t want to cause more problems and difficulty for yourself by allowing the algae to fester and really take hold. SLAM length will take whatever time it takes, but you would think it will remain somewhat shorter because the water is relatively clear.
 
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duraleigh

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Your drain/refill setup appears correct to me. Add the cold refill water to the bottom of the pool and most of it will stay there. siphon or draw the existing and WARMER pool water from the top at the opposite end.
 
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lindsaygib

Active member
Jun 28, 2022
31
Las Vegas
Pool Size
14500
Surface
Plaster
Chlorine
Liquid Chlorine
Hi Lindsay since no one else is taking a crack at your questions I will jump into the fray 😳. Overall I think you’ve got a handle on the direction you need to go. In looking through your water parameters that you listed I think you’d want to reverse your draw and fill locations. Draw low and fill high on the surface. The estimate is from this article: Draining - Further Reading I came up with a negative delta T using avg TDS from here Las Vegas Valley Water District 2022 Water Quality Summary

I understand why you’re not adding much FC but if you see change in water quality I‘d suggest jumping your maintenance level to around 10 ppm FC. You definitely don’t want to cause more problems and difficulty for yourself by allowing the algae to fester and really take hold. SLAM length will take whatever time it takes, but you would think it will remain somewhat shorter because the water is relatively clear.

Thank you! I think I’m more confused😂 Before I wrote this I used the table you did, (my husband works for the water district and sent me that same water quality report you used). I must have read the results wrong because I came up with a negative as well and was thinking that meant pulling from the top. I can’t get past the warm water rising and thinking that you would want to pull from the top. Anyway, I recalculated and got a positive 4, which was way off from my first calculation, and that’s entirely based on the fill water actually being 19 degrees celsius. If it’s any higher then my calculations could be equal or tipped the opposite direction.
Pool water 85
Pwtds 3000
Fill water 66
Fwtds 540
(85-(3000/165))-(66-(540/165))=4

Now I’m not sure I should even try it😩
 

Lake Placid

Well-known member
May 27, 2021
374
St. Louis
Pool Size
17000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When in doubt listen to duraleigh above. And yes you can do it….it’s a pool not brain surgery. 😎. On second glance I’d agree with how you arrived at 4 above. I think I hosed the order of operations when I did it.
 
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