Rookie trying to figure out chemisty.

JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
Maybe I used the test kit wrong but my results yesterday were:
FC - 10
CC - 11
CYA - 39
TA - 110
PH - 7.5
Based on the pool store test the day prior, I had added 2 bags (2#) of shock. There test gave the following results:
FC was 1.9
TC - 2.7
CYA - 70
TA - 84
PH - 7.6
Could the shock have changed it that much? Its 17000 gal. I was concerned about some yellowish algeo dust laying on the
Bottom. Insights & recommendations welcome. Thanks!
 

CrystalRiver

Well-known member
Jun 19, 2020
648
Massachusetts
If your CC is 11, you have a major problem. What does your water look like? Did you add the drops counted in that portion to the drops counted in the FC portion, perhaps? Only the drops added in the second portion count.

CYA can't be measured as 39. Fill the tube to the bottom line, look. If you see the dot, fill to the next line, look. Repeat until the line disappears. Always round up. If the dot disappeared anywhere between 30 and 40, your CYA is 40.

You need to SLAM your pool, using liquid chlorine.
 

JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
If your CC is 11, you have a major problem. What does your water look like? Did you add the drops counted in that portion to the drops counted in the FC portion, perhaps? Only the drops added in the second portion count.

CYA can't be measured as 39. Fill the tube to the bottom line, look. If you see the dot, fill to the next line, look. Repeat until the line disappears. Always round up. If the dot disappeared anywhere between 30 and 40, your CYA is 40.

You need to SLAM your pool, using liquid chlorine.
Pool water is crystal clear.There is some dusty looking debris in the divots. I've vac'd but worried it was yellow algae - that's why I added shock. I've been basically following BBB, except using chlorine tabs instead of liq bleach.
 

Donldson

TFP Expert
LifeTime Supporter
Jun 12, 2009
5,164
NW Ohio
With clear water, it's unlikely your CC is that high. Pretty much impossible.
That's completely incorrect. Water clarity and CC are not related.

CC indicates the presence of an ammonia compound. However, since FC is holding, I'm thinking testing error is likely the issue here. Jill, could you explain step by step how you are testing your FC and CC please? Be as specific as possible.
 

JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
We are following the TF-100 kit instructions for chlorine drop test to get FC (20 yesterday / 21 today times .5). That's 10-10.5
Then we test for CC. Yesterday it was 2 drops to clear. So we multiplied 2x.5=1. I've added 10+1 for a total of 11 CC.
 

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JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
The instructions say time add them. Seems like the FC is still too high. So are the readings still problematic? Especially related to concerns about yellow algae. Should I slam? Or just leave the solar cover off to burn off chlorine? Or add liquid chlorine? We've used tabs as we have a big bucket and I wanted to use them up, then switch to all liquid.
Eek - so worried ware going to have algae 😬
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,896
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Your CYA is 40 ppm as you report above. If so, you do not want to use many more tablets. In your climate, I would not go over a 50 ppm CYA.

Follow the FC/CYA Chart
 

JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
Thank you for the comments. I'm still not sure what my next move should be. There continues to be more dusty looking stuff on the bottom of the pool. However the water is clear.
Adding liquid chlorine to slam seems likely to kill any algae, but would increase the chlorine higher - is that the point?
The app seems to indicate I should decrease TA with acid.
 
Last edited:

JillKC

Silver Supporter
Aug 23, 2019
19
Fredonia, NY
Pool Size
17000
Surface
Vinyl
Chlorine
Liquid Chlorine
No pucks this week. Tested today (results below) and based on the poolmath app added liquid chlorine as recommended.
Confused again... TA is high 110. PH is a bit low 7.2. App says add borax for ph and muriatic acid for TA... Don't they do opposite things to pH? Water remains clear except storm debris.
Today (prior to chlorine add)
FC 2.5
CC 0
TA 110
PH 7.2
CYA 55 or 60
CH 225
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,896
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
App says add borax for ph and muriatic acid for TA...
The app is just putting out data based on what you select. You need to do neither. You must understand the ABCs of Pool Water Chemistry and only address the parameters that truly need adjusting. You needed chlorine added, and you did that. Great. Nothing else is needed.
 
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