SLAM, Alkalinity, and Staining

[natalieh]

I have spent the last several weeks removing stains from the sides of our pool with absorbic acid and scale remover. My pool is crystal clear but my chlorine keeps dropping and failing the overnight test. Last night, I sucked it up and moved forward with SLAM. My water was crystal clear but is now a greenish brown. Target FC was 14 and I over shot to 17 (I failed to update the chlorine %). This morning it is 11.5 so I've added to get back to 14.

Test results last night
FC 0
CC 0
PH 6.7 (because I was working on lowering TA)
TA 120
CH 1100
CYA 35 (didn't know whether to round up or down. It's right in the middle)

PH this morning is 7.0.

While I am SLAMing, can I also add acid to continue working on the TA? Or should I wait?

Any feedback and guidance is appreciated. This is my first SLAM.

 

[Bperry]

I have spent the last several weeks removing stains from the sides of our pool with absorbic acid and scale remover. My pool is crystal clear but my chlorine keeps dropping and failing the overnight test. Last night, I sucked it up and moved forward with SLAM. My water was crystal clear but is now a greenish brown. Target FC was 14 and I over shot to 17 (I failed to update the chlorine %). This morning it is 11.5 so I've added to get back to 14.

Test results last night
FC 0
CC 0
PH 6.7 (because I was working on lowering TA)
TA 120
CH 1100
CYA 35 (didn't know whether to round up or down. It's right in the middle)

PH this morning is 7.0.

While I am SLAMing, can I also add acid to continue working on the TA? Or should I wait?

Any feedback and guidance is appreciated. This is my first SLAM.

You should never allow the pH to go below 7.0. The TA is unimportant compared to pH. The SLAM process is such that you only check the chlorine during the process. You should not be measuring anything else, especially since the pH test is invalid when the FC is over 10ppm.

IMO, stop the SLAM and wait for the chlorine to drop to 10ppm, retest the pH and increase it to 7.0 if needed, then you can restart the SLAM if needed. Is the water green from algae or from metal staining?

 

[natalieh]

The low pH was only temporary and I was aerating it the water to bring it back up. My TA started at 190 which was causing scaling along the walls.

Thank you for confirming that the FC is all I should be concerned with during the SLAM. I am unsure if the color is from algae or metal staining, but I am going to assume it is metal. When I have had tea colored water and I added sequestrant, the water cleared quickly. I had no visible algae when I began the SLAM.

 

[Bperry]

The low pH was only temporary and I was aerating it the water to bring it back up. My TA started at 190 which was causing scaling along the walls.

Thank you for confirming that the FC is all I should be concerned with during the SLAM. I am unsure if the color is from algae or metal staining, but I am going to assume it is metal. When I have had tea colored water and I added sequestrant, the water cleared quickly. I had no visible algae when I began the SLAM.

The TA doesn’t cause scaling, it’s all the calcium you have in the water. You should consider replacing it to get the calcium down to 300ppm or so. Low pH can damage equipment and surfaces so don’t let it get low just for the TA.

 

[natalieh]

The low pH was only temporary and I was aerating it the water to bring it back up. My TA started at 190 which was causing scaling along the walls.

Thank you for confirming that the FC is all I should be concerned with during the SLAM. I am unsure if the color is from algae or metal staining, but I am going to assume it is metal. When I have had tea colored water and I added sequestrant, the water cleared quickly. I had no visible algae when I

 

[duraleigh]

I think you are onto something about your colored water from metals and not algae.

If your pool is clear now as you say, I would simply bring your FC up around 10 ppm and hold it there for a couple of days and observe. That scale remover can account for much of your FC loss and you may not need to SLAM at all.

Can you post a pic of your pool water color?

Take this one step at a time and I think we will have you on a good path.

 

[natalieh]

I think you are onto something about your colored water from metals and not algae.

If your pool is clear now as you say, I would simply bring your FC up around 10 ppm and hold it there for a couple of days and observe. That scale remover can account for much of your FC loss and you may not need to SLAM at all.

Can you post a pic of your pool water color?

Take this one step at a time and I think we will have you on a good path.

Thank you for the feedback. I'm holding at 14 FC tonight and I'll check again in the morning. I'll get a picture then and share it.

 

[natalieh]

I think you are onto something about your colored water from metals and not algae.

If your pool is clear now as you say, I would simply bring your FC up around 10 ppm and hold it there for a couple of days and observe. That scale remover can account for much of your FC loss and you may not need to SLAM at all.

Can you post a pic of your pool water color?

Take this one step at a time and I think we will have you on a good path.

Good morning! Attached are my pool pictures. We had a hard rain last night and it added about an inch of water to the pool. I did a full test this morning to see where it stands:

FC - 10
CC - .5
TA - 130
CYA- 30
pH- 7.2

Do you think I should continue with the SLAM? Or move on with the metal treatment?

 

[duraleigh]

Unfortunately, that's a little too murky so I suggest you bring your FC back to SLAM level and continue the SLAM to it's completion. The major cause of that murkiness may be filtration so keep your pump running 24/7 and make sure your psi on the filter has not risen too high to warrant backwash.

You've got a ways to go but I think it might start to clear pretty suddenly..