Chemical values too high :(

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
Hi,

We moved into a house with a pool about 10 days ago. The water looks really nice not even a tiny bit green. The previous person who lived here had a company come every week to take care of the pool (I found a chlorine tablet in the skimmer). The first thing I did was to clean the filter - which seemed necessary. Then I took a sample to Lesslie's to get an idea of what was going on. They said everything is fine Chlorine is around 5ppm.... I should have known better.
Today I received my test kit I got the Taylor K-2006 and these are the results:

pH = 7.6
FC = 30ppm
CH = 750ppm
CYA ~300ppm (diluted test)
TA = 175ppm

Temperature: 72F
Pump is running 8h a day
The pool gets about 7h of sun a day
The pool is about 7500 gallons
I scrub the pool every 2 or 3 days

We live in Las Vegas and it is still around 90F so we can still use the pool in the afternoon which we do since I thought it was in good health.

So all the values except PH seem really high. My assumption after loots of googeling is that I have to drain 1/3 or 1/4 of the water to get the CYA down and then use liquid chlorine/ bleach. Is there anything else I can or should do? This is our first pool and I am not really sure what to do next. Is it still safe to use the pool? FC is high but most of it should have bonded with CYA (maybe?!).
Thank you so much for your help!
 
Last edited:

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
15,510
Evans, Georgia
Cactus, welcome to TFP :wave:

Yup....your pool is loaded to the brim with chemicals. Extra high chemicals can be damaging to pool surface and equipment as well as can make swimming less pleasant.

A way to determine a better idea what your CYA actually is is to do a diluted test. Take equal parts of pool water and tap water and mix well. Then use this as your pool water portion to run the test again but double the result.

This will give you a better idea on how much you're goimg to have to drain to get that CYA down.

If you could please fill out a signature line (found under settings) with details about your pool's finish, equipment; how you sanitize and test. Lots of details help us help you without repeatedly asking questions.

Maddie :flower:
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Welcome to the forum!
With a CH of 750 ppm and your high CYA, your best bet is to plan a full drain and refill. Your fill water CH is about 250 ppm. You have to plan to drain and refill about every 2 - 2.5 years if you are not using soft water as make up water due to evaporation.
I would suggest considering a SWCG over the winter.
I suggest you read ABC's of Pool Water Chemistry.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If you do drain your pool 100%, you can use this opportunity to find out the exact water volume. After emptying as much as possible, go out and find your house's water meter (near the street somewhere). Open the lid(s) and take a picture of the numbers, or write them down. Fill your pool to halfway up the opening of the skimmer. Then go out and read the meter again. The difference between those two before and after numbers will be the water volume of your pool. That number will be very handy for figuring out how much of any pool chemical you add. And then you can update your signature and get rid of the squiggly (~).

The less water you use in the house during the fill, the more accurate a number you'll get. So no showers, no laundry, minimize flushes, and turn off any garden landscaping irrigation.

Welcome to TFP! Great job so far in grabbing an excellent test kit, and figuring out early to ignore the pool store! You're in great hands with Marty and Maddie! They'll get you back on track and swimming in crystal clear, healthy water in no time.
 

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
Thank you so much for the quick responses :) I am very happy that I found this forum:swim:
@YippeeSkippy thanks for the tip with the signature.

I ran the CYA test again this time diluted. It is still more than 100ppm maybe 150ppm if I multiply that by 2 I get CYA=300ppm. (I will also update my original post)

It looks like I have to drain 90% to get to a reasonable CYA value. I already bought a pump which should arrive on Monday. We are just renting so I am a bit concerned about damaging the pool when completely draining it. I would feel more comfortable with a no drain water exchange. Would this still get the CYA down to 50ppm?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
This time of year I do not see a large risk of harming the pool by draining, but up to you. The best way to do a quick drain is rent a sump pump from Home Depot. Your pool volume would be drained in just over 2 hours. So a 4 hour rental window is all you need. Do determine where you plan to send the effluent. I put ours down the sewer cleanout. CCRWD is fine with that.

Your high CYA will help with the no drain. But I suspect your fill water is the same temperature or even warmer than the pool water. So as you will be adding your pool water to the shallow end and pumping from the deep end, you may get some mixing. I would suggest exchanging at least 8000 gallons or 10% more than the pool volume. That hopefully will get your CYA and CH down to reasonable levels.
 

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
Thank you @mknauss I appreciate your help :)

yes I will replace at least 8000 +10% to make sure that most of the old water gets out. Is it true that within CCRWD it will only cost me about $50 to replace the whole pool water?
Is there anything else I need to be aware of before, after or during the drain except the obvious that I need to monitor the chemical levels afterwards?
I plan on only adding liquid chlorine after the drain unless my CYA is too low which I don't expect to happen.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
You buy your water from LVVWD. CCWRD (I messed up on that acronym above) charges a flat rate for sewer service each year. I suspect your landlord pays that. Your pool is only slightly larger than ours. At just over $3 per 1000 gallons, it does not cost much to drain and refill.

Your fill water TA is about 130 ppm and CH 250 ppm. So you will need acid at the start as your pH will climb pretty quickly with the elevated TA. Test the pH every few days and add acid to lower it to 7.4 or so until your TA gets to 80 or less. Maintain your FC based on the FC/CYA Chart
 
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cactus_LV

Member
Oct 16, 2020
13
Las Vegas
I finished exchanging the water today and have much better values now :)

FC 4.5ppm
CC 0ppm
PH 7.8
TA 150ppm
CH 250ppm
CYA 37ppm

My plan was to lower the PH to 7.6 (add 14oz Muriatic acid [14.5% from Home Depot]) and add a little bit of liquid chlorine to get it to 5ppm. The TFP app tells me to lower the PH to 7.0-7.2 to lower the TA. Should I go that low or should I start with PH of 7.4?
I can let my waterfall run for most of the day to hopefully get the PH back up after that.

In the TFP app do I use the bleach setting when using the Home Depot liquid chlorine?
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Very efficient exchange to get your CH down to that level.

While your TA is high you can lower your pH to 7.2. It will rise quickly. Once your TA is 80 or below, then only lower pH to 7.6 when it gets to 8.
Home Depot chlorine is 10% bleach.
 

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
I added the acid and chlorine yesterday night and just took the measurements again. I guess I didn't add enough of both.

FC 4ppm
CC 0ppm
PH 7.5
TA 150ppm

I will add some more tonight.

How long should I wait to measure again and expect the TA to go down and the PH to go up?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When your pH rises to 7.5 or higher, lower it to 7.2. That process will reduce the TA. As your TA lowers, it will take longer for the pH to rise. Depending on any aeration, it may take a day or three for the pH to rise.
Once your TA gets below 80, let your pH rise to 7.8 - 8 and lower to 7.6.

As your evaporation is lessening your TA and pH will become more stable. But starting next April, your evaporation will go up and you will need to add acid at least once per week to lower the pH and TA from the fill water.
 

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
This is very helpful information. Thank you so much @mknauss!

Regarding the chlorine how often do I need to check that and can I let it fall to the minimum (3ppm) and the increase back to somewhere in the middle of the target range (5-7ppm)?

Is my CYA of 37ppm ok?
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
You cannot measure a CYA of 37 so round up to 40.
Do not let FC go to minimum. I suggest keeping FC in target range by increasing it above target when you add chlorine.During winter your FC loss will lessen. But again in early April, you will need to add chlorine daily.
 

DanF

Silver Supporter
Mar 17, 2019
333
Chandler, AZ
I will defer to the guru @mknauss, but I would recommend a CYA level of 50, especially since you are in a climate that gets a lot of sunlight and warmth.

You mentioned in your first post that you have chlorine tabs; if so you could accomplish raising FC and CYA at the same time. According to Pool Math, for your size pool a 3" tablet (8 ounces) will raise the FC by 7.3 and the CYA by 4.4. So I would recommend putting two tabs in a floater, wait about a week and test again. Then stop using tabs.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
You can raise the CYA a bit if you like. This time of year is not as critical.
Again, in April, you will want to have your CYA at 50 ppm and even go to 60 ppm in June.
 

cactus_LV

Member
Oct 16, 2020
13
Las Vegas
Thank you so much @mknauss and @DanF. I don't have tablets on hand right now the previous guy who lived here left one in the floater. I will leave the CYA as is for now and add more in Spring.
I added more acid which should have lowered the PH to 7.2 - 20H later it is back to 7.6 but the TA is still 150ppm. I guess I need more acid than chlorine :D
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
36,116
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If you use the PoolMath app it will tell you what TA drop to expect when you add the acid. Be sure you have up to date test results inputted into the app.
 

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