Pool Opening, When to Balance Alkalinity & Calcium Hardness

Bluldr

Gold Supporter
May 29, 2018
2
Denver, CO
Bought a house with a pool (my first) in the Winter of 2017. With TFP's guidance, I've been doing relatively well (thank you). Last summer was the best, all chemicals stayed pretty close to ideal and water was beautiful. I am preparing to open the pool in the next few weeks and I peeked under the cover (normal dirt on the bottom, water is clear) and pulled a water sample. Test results are a little surprising with low alkalinity and calcium hardness. I would like to know if it is best practice to get these numbers up before doing my Pool Opening SLAM or do the SLAM first and then adjust Alkalinity (add baking soda) and Calcium Hardness (add Calcium Chloride)?

Closing Test Numbers: Pre-Opening Test Numbers:
10/5/2020 5/2/2021
TTL Chlorine 3.72 .17
Free Chlorine 3.72 .15
Combined Chlorine 0 .02
PH 7.8 7.7
TTL Alkalinity 61 28
Calcium Hardness 311 120
CYA Stabilizer 42 23
Water Temp 82 55

Thanks for your thoughts.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
25,665
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The water sample is invalid until the pool pump is running and you have circulated the water for 24 - 48 hours to mix it.

What do you think you need to SLAM to pool at opening? I don't.
 

Bluldr

Gold Supporter
May 29, 2018
2
Denver, CO
Bought a house with a pool (my first) in the Winter of 2017. With TFP's guidance, I've been doing relatively well (thank you). Last summer was the best, all chemicals stayed pretty close to ideal and water was beautiful. I am preparing to open the pool in the next few weeks and I peeked under the cover (normal dirt on the bottom, water is clear) and pulled a water sample. Test results are a little surprising with low alkalinity and calcium hardness. I would like to know if it is best practice to get these numbers up before doing my Pool Opening SLAM or do the SLAM first and then adjust Alkalinity (add baking soda) and Calcium Hardness (add Calcium Chloride)?

Closing Test Numbers: Pre-Opening Test Numbers:
10/5/2020 5/2/2021
TTL Chlorine 3.72 .17
Free Chlorine 3.72 .15
Combined Chlorine 0 .02
PH 7.8 7.7
TTL Alkalinity 61 28
Calcium Hardness 311 120
CYA Stabilizer 42 23
Water Temp 82 55

Thanks for your thoughts.

The water sample is invalid until the pool pump is running and you have circulated the water for 24 - 48 hours to mix it.

What do you think you need to SLAM to pool at opening? I don't.
Oh, well, there you go, shows how much of a novice I am. I thought I was getting ahead of the game by checking chemistry early, but it makes sense that the water needs to get mixed up first. Thank you! RE: SLAM at opening. I guess I don't officially SLAM, but I've figured out that since I drop the level down a couple of feet in the fall, I have to add water from my well back into the pool in the Spring. I have to watch the chlorine level and keep up while adding well water or, in the past I have experienced algae within a couple of hours.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
25,665
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Add chlorine in whatever amount you think you need when opening, let the water mix for a while, then do a full set of tests.