My CYA gradually disappears. My location in central Minnesota. Pool temp is kept between 83F and 87F. Whenever we are not in the pool, the safety cover is on, so the pool gets relatively no sunlight. To counter act the CYA disappearance, I periodically add dichlor or trichlor instead of liquid bleach. Any idea what is happening here? This past week the chlorine suddenly went to zero and the water got slightly cloudy, so I added a lot of liquid bleach. Today (Aug 5), I noticed that the CYA is suddenly lower. Hmmm....
Here is a complete history of this year's chem numbers and the chems added:
City Water tested on 2011 05/28
FC 1
pH 7.8
T/A 120
CH 130
Temp 48F
2011 05/17 Open pool and start pump
FC 0
CC 0
TC 0
pH 7.5
T/A 130
CH 60
CYA 0
Temp 48F
Borates 15ppm
2011 05/18
FC 3
CC 25
TC 28
pH 7.2
T/A 130
2011 05/19
FC 2
CC 19
TC 21
pH 7.2
T/A 130
CH 70
CYA 30
Temp 49F
2011 05/21
FC 1
CC 12
TC 13
pH 7.0
2011 05/22
FC 1
CC 7
TC 8
pH 7.0
2011 05/23
FC 7
CC 1
TC 8
pH 7.0
Temp 54F
2011 05/24
FC 8
CC 1
TC 9
pH 7.2
Temp 54F
2011 05/25
pH 7.3
2011 05/26 1
FC 12
CC 1
TC 13
pH 7.4
Temp 54F
2011 05/26 2
FC 16
CC 1
TC 17
pH 7.4
T/A 120
CH 70
CYA 35
Temp 56F
2011 06/02
FC 5.5
CC 2
TC 7.5
pH 7.7
T/A 100
CH 70
CYA 30
Temp 81F
2011 06/05
FC 2.5
CC 0.5
TC 3
pH 7.5
Temp 89F
2011 06/07
FC 6
CC 1
TC 7
pH 7.6
Temp 87F
2011 06/09
TC 2
pH 7.8
Temp 82F
2011 06/11
FC 7
CC 0.5
TC 7.5
pH 7.8
Temp 78F
2011 06/18
FC 7.5
CC 0.5
TC 8
pH 7.8
Temp 87F
2011 06/25
FC 2
CC 0.5
TC 2.5
pH 7.8
T/A 100
CH 70
CYA 33
Temp 87F
2011 07/02
FC 1.5
CC 0.5
TC 2
pH 7.7
Temp 88F
2011 07/03
FC 6
CC 0.5
TC 6.5
pH 7.6
Temp 88F
2011 07/05
FC 0
pH 7.8
Temp 84F
2011 07/06
FC 23
CC 0.5
TC 23.5
pH 8.2
Temp 83F
2011 07/07
FC 19.5
CC 0.5
TC 20
pH 8.2
Temp 83F
2011 07/08
FC 14
CC 0.5
TC 14.5
pH 7.4
T/A 90
CH 70
CYA 30
Temp 82F
2011 07/09
FC 9
CC 0.5
TC 9.5
pH 7.4
T/A 90
CH 80
CYA 25
Temp 86F
2011 07/10
FC 7
CC 0.5
TC 7.5
pH 7.4
Temp 85F
2011 07/13
FC 12
CC 0.5
TC 12.5
pH 7.4
Temp 82F
2011 07/16
FC 10
CC 0.5
TC 10.5
pH 7.5
Temp 78F
2011 07/22
FC 12
CC 0
TC 12
pH 7.4
T/A 90
CH 80
CYA 20
Temp 88F
2011 07/25
FC 8
CC 0.5
TC 8.5
pH 7.5
Temp 86F
2011 07/29
FC 8
CC 0.5
TC 8.5
pH 7.5
T/A 80
CH 70
CYA 30
Temp 87F
2011 07/31
FC 6.5
CC 0.5
TC 7.0
pH 7.4
T/A 80
CH 70
CYA 30
Temp 86F
2011 08/02 1
FC 0
pH 7.2
Temp 83F
2011 08/02 2
FC 13.5
CC 1.0
TC 14.5
pH 7.3
Temp 84F
2011 08/03
FC 17.5
CC 1.0
TC 18.5
pH 7.4
Temp 83F
2011 08/04
FC 13.0
CC 0.5
TC 13.5
pH 7.5
Temp 83F
2011 08/05
FC 8.0
CC 0.5
TC 8.5
pH 7.5
T/A 100
CH 70
CYA 10
Temp 82F
Borates 20ppm
Chemicals added and the expected result based on TFP calculator iPhone app:
Pool startup
2011 05/17
84oz dichlor FC 20.2
CYA 18 pH down .77
4 jugs 12.5% chlorine FC 28.8
2 boxes Borax pH up .35
2011 05/18
32oz dichlor FC 7.7
CYA 7 pH down .29
2 jugs 12.5% chlorine FC 14.4
2 boxes Borax pH up .35
2011 05/19
4 jugs 12.5% chlorine FC 28.8
2011 05/20
2 jugs 12.5% chlorine FC 14.4
2011 05/21
2 jugs 12.5% chlorine FC 14.4
2011 05/22
4 jugs 12.5% chlorine FC 28.8
2011 05/23
1 jugs 12.5% chlorine FC 7.2
2011 05/24
1 jugs 12.5% chlorine FC 7.2
2011 05/26
20oz dichlor FC 4.8
CYA 4 pH down .18
2011 06/01
1 jugs 12.5% chlorine FC 7.2
2011 06/02
32oz dichlor FC 7.7
CYA 7 pH down .29
2011 06/05
1 jugs 12.5% chlorine FC 7.2
2011 06/08
16oz dichlor FC 3.8
CYA 3 pH down .15
2011 06/15
1 jugs 12.5% chlorine FC 7.2
2011 06/25
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 06/27
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/02
1 jugs 12.5% chlorine FC 7.2
2011 07/05
3 jugs 12.5% chlorine FC 21.6
2011 07/07
2 quarts 31.45% 20 baume muriatic acid pH 0.7 down
2011 07/10
3 lbs baking soda pH up 0.4
3 tablets 7oz trichlor FC 8.3
CYA 5 pH down .45
2011 07/16
2 tablets 7oz trichlor FC 5.6
CYA 3 pH down .30
2011 07/24
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/28
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/31
3 lbs baking soda pH up 0.4
1 jugs 12.5% chlorine FC 7.2
2011 08/02
3 jugs 12.5% chlorine FC 21.6
1 jugs 12.5% chlorine FC 7.2
Here is a complete history of this year's chem numbers and the chems added:
City Water tested on 2011 05/28
FC 1
pH 7.8
T/A 120
CH 130
Temp 48F
2011 05/17 Open pool and start pump
FC 0
CC 0
TC 0
pH 7.5
T/A 130
CH 60
CYA 0
Temp 48F
Borates 15ppm
2011 05/18
FC 3
CC 25
TC 28
pH 7.2
T/A 130
2011 05/19
FC 2
CC 19
TC 21
pH 7.2
T/A 130
CH 70
CYA 30
Temp 49F
2011 05/21
FC 1
CC 12
TC 13
pH 7.0
2011 05/22
FC 1
CC 7
TC 8
pH 7.0
2011 05/23
FC 7
CC 1
TC 8
pH 7.0
Temp 54F
2011 05/24
FC 8
CC 1
TC 9
pH 7.2
Temp 54F
2011 05/25
pH 7.3
2011 05/26 1
FC 12
CC 1
TC 13
pH 7.4
Temp 54F
2011 05/26 2
FC 16
CC 1
TC 17
pH 7.4
T/A 120
CH 70
CYA 35
Temp 56F
2011 06/02
FC 5.5
CC 2
TC 7.5
pH 7.7
T/A 100
CH 70
CYA 30
Temp 81F
2011 06/05
FC 2.5
CC 0.5
TC 3
pH 7.5
Temp 89F
2011 06/07
FC 6
CC 1
TC 7
pH 7.6
Temp 87F
2011 06/09
TC 2
pH 7.8
Temp 82F
2011 06/11
FC 7
CC 0.5
TC 7.5
pH 7.8
Temp 78F
2011 06/18
FC 7.5
CC 0.5
TC 8
pH 7.8
Temp 87F
2011 06/25
FC 2
CC 0.5
TC 2.5
pH 7.8
T/A 100
CH 70
CYA 33
Temp 87F
2011 07/02
FC 1.5
CC 0.5
TC 2
pH 7.7
Temp 88F
2011 07/03
FC 6
CC 0.5
TC 6.5
pH 7.6
Temp 88F
2011 07/05
FC 0
pH 7.8
Temp 84F
2011 07/06
FC 23
CC 0.5
TC 23.5
pH 8.2
Temp 83F
2011 07/07
FC 19.5
CC 0.5
TC 20
pH 8.2
Temp 83F
2011 07/08
FC 14
CC 0.5
TC 14.5
pH 7.4
T/A 90
CH 70
CYA 30
Temp 82F
2011 07/09
FC 9
CC 0.5
TC 9.5
pH 7.4
T/A 90
CH 80
CYA 25
Temp 86F
2011 07/10
FC 7
CC 0.5
TC 7.5
pH 7.4
Temp 85F
2011 07/13
FC 12
CC 0.5
TC 12.5
pH 7.4
Temp 82F
2011 07/16
FC 10
CC 0.5
TC 10.5
pH 7.5
Temp 78F
2011 07/22
FC 12
CC 0
TC 12
pH 7.4
T/A 90
CH 80
CYA 20
Temp 88F
2011 07/25
FC 8
CC 0.5
TC 8.5
pH 7.5
Temp 86F
2011 07/29
FC 8
CC 0.5
TC 8.5
pH 7.5
T/A 80
CH 70
CYA 30
Temp 87F
2011 07/31
FC 6.5
CC 0.5
TC 7.0
pH 7.4
T/A 80
CH 70
CYA 30
Temp 86F
2011 08/02 1
FC 0
pH 7.2
Temp 83F
2011 08/02 2
FC 13.5
CC 1.0
TC 14.5
pH 7.3
Temp 84F
2011 08/03
FC 17.5
CC 1.0
TC 18.5
pH 7.4
Temp 83F
2011 08/04
FC 13.0
CC 0.5
TC 13.5
pH 7.5
Temp 83F
2011 08/05
FC 8.0
CC 0.5
TC 8.5
pH 7.5
T/A 100
CH 70
CYA 10
Temp 82F
Borates 20ppm
Chemicals added and the expected result based on TFP calculator iPhone app:
Pool startup
2011 05/17
84oz dichlor FC 20.2
CYA 18 pH down .77
4 jugs 12.5% chlorine FC 28.8
2 boxes Borax pH up .35
2011 05/18
32oz dichlor FC 7.7
CYA 7 pH down .29
2 jugs 12.5% chlorine FC 14.4
2 boxes Borax pH up .35
2011 05/19
4 jugs 12.5% chlorine FC 28.8
2011 05/20
2 jugs 12.5% chlorine FC 14.4
2011 05/21
2 jugs 12.5% chlorine FC 14.4
2011 05/22
4 jugs 12.5% chlorine FC 28.8
2011 05/23
1 jugs 12.5% chlorine FC 7.2
2011 05/24
1 jugs 12.5% chlorine FC 7.2
2011 05/26
20oz dichlor FC 4.8
CYA 4 pH down .18
2011 06/01
1 jugs 12.5% chlorine FC 7.2
2011 06/02
32oz dichlor FC 7.7
CYA 7 pH down .29
2011 06/05
1 jugs 12.5% chlorine FC 7.2
2011 06/08
16oz dichlor FC 3.8
CYA 3 pH down .15
2011 06/15
1 jugs 12.5% chlorine FC 7.2
2011 06/25
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 06/27
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/02
1 jugs 12.5% chlorine FC 7.2
2011 07/05
3 jugs 12.5% chlorine FC 21.6
2011 07/07
2 quarts 31.45% 20 baume muriatic acid pH 0.7 down
2011 07/10
3 lbs baking soda pH up 0.4
3 tablets 7oz trichlor FC 8.3
CYA 5 pH down .45
2011 07/16
2 tablets 7oz trichlor FC 5.6
CYA 3 pH down .30
2011 07/24
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/28
1 tablet 7oz trichlor FC 2.8
CYA 2 pH down .15
2011 07/31
3 lbs baking soda pH up 0.4
1 jugs 12.5% chlorine FC 7.2
2011 08/02
3 jugs 12.5% chlorine FC 21.6
1 jugs 12.5% chlorine FC 7.2