Add calcium?

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H

HooStat

Member
Aug 31, 2020
15
Calabasas, CA
I have brand new pebble (mini Pebble, black). Fill was finished 4 days ago. TA is 80, pH is 7.8 (just added acid to go to 7.6) and calcium is 100. No chlorine or CYA yet.

The recommendations are for pH in the 7.2-7.6 range depending on who you listen to. The plaster company wants it low (7.2), but they assume calcium 250-400.

So, should I add calcium and go to a lower pH? Or should I keep it on the higher side of pH with a lower calcium. In my previous pool, I was always fighting calcium and so I am somewhat reluctant to add calcium since it is hard to remove. I also don't want to ruin the pool finish or concrete coping.

Thanks for any suggestions
 
Get FC in your pool. Far and away that takes precedence over any calcium issues.

To keep the FC in your pool, get CYA in there at the same time.

With a CH fill water of 100, you will virtually NEVER have any CH problems. FC should always be your number one priority. Get some in your pool.
 
HooStat said:
Or should I keep it on the higher side of pH with a lower calcium.
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That would be my choice. Make sure to use the PoolMath APP to keep your CSI "slightly" positive for the first 30 days which should help encourage a good cure. After 30 days, CSI can be slightly negative. You're one of the rare CA's with such a low CH. Nice.

Even though you anticipate adding an SWG in Oct which would require a CYA of 70, perhaps increase the CYA only to about 40 or 50 for now and balance as a non-salt pool (first 30 days minimum) and reference the FC/CYA Levels.
 
duraleigh said:
Get FC in your pool. Far and away that takes precedence over any calcium issues.

To keep the FC in your pool, get CYA in there at the same time.

With a CH fill water of 100, you will virtually NEVER have any CH problems. FC should always be your number one priority. Get some in your pool.
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Will do. That is today's job (they wanted me to wait a few days for chlorine). Thanks.
 
Texas Splash said:
That would be my choice. Make sure to use the PoolMath APP to keep your CSI "slightly" positive for the first 30 days which should help encourage a good cure. After 30 days, CSI can be slightly negative. You're one of the rare CA's with such a low CH. Nice.

Even though you anticipate adding an SWG in Oct which would require a CYA of 70, perhaps increase the CYA only to about 40 or 50 for now and balance as a non-salt pool (first 30 days minimum) and reference the FC/CYA Levels.
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Got it. Thanks -- I am definitely trying to keep the CSI on the slightly positive side, which is what prompted my question. Will get the CYA and chlorine in and see what happens.
 
Do not let the bags hit the pool finish. Hang them from a broom handle or something.

Or, them in the skimmer. Just do not plug off the water flow in the skimmer. Squeeze them a bit once they get mushy and the CYA will dissolve quickly.
 
Stat, I mentioned above to let the pH ride a little high to help compensate for the low CH, but that alone may not be enough. Double-check your numbers in PoolMath please. When I run everything, even with a pH of 7.8 it's still showing a negative CSI of somewhere around -0.3. If you're getting the same thing, I think it would be prudent to add some calcium. 28 lbs of calcium should increase the CH by 100, taking your CH to 200 and your CSI to about 0.03.

Perhaps do one last sanity check on your end to ensure you're not riding too low of a CSI on that new plaster.
 
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Texas Splash said:
even with a pH of 7.8 it's still showing a negative CSI of somewhere around -0.3
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I will check everything a little later today. But my calculations also show a slightly negative CSI. It is a pebble pool, so it should be a lot more resistant to many issues just because there is a lot less plaster surface area interacting with the water. But I would like it to be 0 or higher too. I can get some calcium tomorrow or Wed, but will keep the pH on the higher side until then.
 
Just added about 5 pounds of CYA and some chlorine. Will test later today to see what happened.
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I would much rather you said, "I put in 120 oz of CYA to get to 30 ppm (your dose of 5 lbs is NOT ENOUGH and I can't help you with "some chlorine" but I'll bet it's not enough, either.

Sorry to be blunt but I am trying to impress upon you that CSI has little bearing on sanitizing your pool.......that belongs to chlorine and until you learn that, I am concerned you will chase CSI around your green pool for what's left of the swim season. Please manage your pool the way you see fit but my suggestion to you would be to get off CSI and sanitize your pool first.
 
I was in the same situation 10 days ago ... I compared my pool builder's chemistry requirements, to Pebbletec's requirements, to TFP's recommendations, and came up with curing targets.

1599567087684.png

Since my warranty is with the pool builder, I made sure my curing targets were within range of their requirements.

One difference for me is that my auto-fill is plumbed into my water softener line, so while my fill water had CH in it, my make-up water does not.

I will also be switching over to a SWCG after the plaster has finished curing. So I made a cheat sheet, laminated it, and stuck it in my TF-100 test kit case.

The front of the cheat sheet is:

1599567244395.png

You'll notice I changed my plaster curing target for pH to 7.6 when I made the cheat sheet, as it's easier to maintain a slightly positive CSI with 7.6 than with 7.3 pH, and they're both within the builder's requirement range.

I also have an inline chlorinator, so I only added 20ppm of CYA to my pool on the 1st day, and have been using trichlor pucks to add additional CYA into the pool, while helping with chlorination as well. Once my CYA reaches 60, I'll stop with the pucks and stick to liquid chlorine until we are ready to add salt and turn on the SWCG.

On the back of my cheat sheet, I just have the CYA/FC chart for easy reference. So as my CYA is going up over time due to using the trichlor pucks, I'm adjusting my FC target:

1599567278873.png
 
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duraleigh said:
Sorry to be blunt but I am trying to impress upon you that CSI
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I appreciate the help. Sorry I wasn't clear -- I didn't have enough socks to put all 9 pounds in at once, and, as you know, it takes time for the CYA to dissolve. The last 4 pounds (it comes in a 9 pound container) went in yesterday afternoon and looks like it is still dissolving this morning.
 
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Stat, I want to make sure we reiterate a few basic things for you:
1. Always make sure to follow the FC/CYA Levels to keep your pool properly sanitized. That's almost always #1 in pools. The last thing you want in new plaster is algae.
2. I mentioned CSI earlier, and it is a factor noted in the PoolMath APP, but in most cases as long as you maintain the required TFP levels you should be fine. As a fairly new TFP member, I don't want you to be overwhelmed with new terminology. In almost all cases the ABCs of Pool Water Chemistry will guide you in the right direction.
3. Follow your builder's recommendations. That will of course be important for your warranty.
4. Take your time with testing. Practice makes perfect. Hopefully you have a magnets speedstir. If not, I would encourage you to get one.

While you have prior pool experience with hard water, we want to make sure your new oasis gets off to a good (clear) start. So if you have any other questions, just let us know. Enjoy. :swim:
 
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No problem. This question was focused on calcium but I appreciate the emphasis on chlorine. CYA is now about 35 and I added a gallon of 10% bleach yesterday and a gallon of 12% bleach today. Since there is no pool cover and a ton of sun, I suspect that the chlorine is just burning off very quickly. Hopefully this will get me to measurable levels this evening and they will last until the morning.
 
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