New plaster - when to add calcium?

Benwuk

Member
Jul 21, 2019
5
Austin
New plastering job should be finished tomorrow , tested water from the tap today and got the following readings:

TA : 80
Calcium Hardness : 50 ppm

Given the low calcium hardness , my CSI is going to be really out of wack. I've read conflicting advice on when to add calcium hardness after a replaster. Some say it's too strong to add at the start, the new plaster will naturally raise the calcium levels as it cures and to wait awhile until trying to adjust.

Others, seem to recommend adding slowly (max 10lbs at a time) , pre-mixed in water to the pool (morning and night) and raise to 150ppm as soon as possible. Even at 150ppm with 80 TA that's going to put my CSI too low (assuming stable PH , water temp and CYA) ?

I'm assuming the second opinion of adding slowly after the water is filled is the better option, should I push it to 250ppm asap to get my CSI in a good place?

Let me know of any other options to get the CSI in check fast - I don't want plaster problems.
 

HermanTX

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May 20, 2020
2,552
Katy TX
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Plaster
Chlorine
Liquid Chlorine
Did you download or review the startup guidelines for your specific plaster? The mfg. guidelines should be followed. The plaster company should provide you that info or you can access via website of plaster mfg.

Alternatively, you can follow the NPC guidelines - attached.
 

Attachments

  • NPC Swimming Pool Start Up.pdf
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  • npc-start-up-card-lsi.pdf
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HermanTX

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May 20, 2020
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Thanks , no they start today with the plaster - just getting ahead of it.
That is great that you tested your fill water - many forget to do that. At least you know where you are starting.
Discuss with the supervisor of the plaster as to what they plan to add when completed and start to fill.
Retest your water again as it starts to fill.

BTW - here are some other tips for plaster and fill starting
Day of Plaster

  1. Clean up around the pool area the day before - brush any dirt/mud or debris that could be tracked into the pool during or after plaster
  2. Verify that the bags of plaster are the proper type and color you selected on morning of plaster.
  3. Take a sample of the mixture when they are applying it to the pool by pouring some in a small clear plastic cup (good for reference later)
  4. Do they have all the proper return nozzles and drain covers (type and color) to place after plaster installed
  5. Have you tested your fill water? Are you filling with softened water or regular tap water?
  6. Have your hose ready (and clean) as it will be laying in the pool.
  7. Tie a sock or cloth around the nozzle so it does not sit on the plaster
  8. Ensure you take note (or a picture) of your water meter reading before you start to fill
  9. Be prepared to take note of your water meter as the pool reaches certain levels, i.e bottom of bottom step, top of bottom step, etc. (it helps in the future to know volume of your pool at certain levels - should you ever have to drain portion of it)
  10. Plan to set an alarm every 4 hours (or so) to ensure hose is still in pool, no debris blew into pool, etc.
  11. Take a picture of any chemicals they bring on site that they plan to dump in when they start to add water to pool
  12. Continue to fill pool to center of water tile or center of skimmer. Take picture of water meter at end of fill
  13. Get clear instructions from PB as what to do the day the pool is full - how often to brush, will the pump be turned on, etc.
  14. Define with PB when he will be back out to set up water chemistry.
 

Benwuk

Member
Jul 21, 2019
5
Austin
Thanks for the tips! They've finished the plaster and we've added the first chemicals (startup tec). Acorns unfortunately are starting to fall and a few have popped into the pool since it's been filling. Is it ok for me to gently use the pool net to skim them off the bottom? Or better to leave until pool is full completely....trying to weigh up if the acorns or me skimming the bottom with the net is going to cause more problems...?
 

HermanTX

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May 20, 2020
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Others may have ideas but I would take my brush and gently push them to the main drain area.
 

Benwuk

Member
Jul 21, 2019
5
Austin
Last question....

NPC suggests calcium hardness not to exceed 200 and keep TA around 70...

That conflicts with the CSI rating ....should I just start balancing to get CSI above -0.3?
 

HermanTX

Gold Supporter
May 20, 2020
2,552
Katy TX
Pool Size
14600
Surface
Plaster
Chlorine
Liquid Chlorine
Last question....

NPC suggests calcium hardness not to exceed 200 and keep TA around 70...

That conflicts with the CSI rating ....should I just start balancing to get CSI above -0.3?
In my pool and research, the pH has a big influence on my CSI. So maintain the pH in a range of 7.4 to 7.8. Because your calcium is on the low side, your CSI may be indicating negative. If you can raise the CH up you can move towards 0 or a slightly positive CSI as the the plaster cures. Also, not sure if you have a SWCG, but once the plaster is cured and established, it's best to maintain a slightly negative CSI to avoid scaling issues on your SWCG.

Also, falling out of range on CSI does not have an immediate impact, it may take months at being out of range to show any issues so don't overreact or stress about CSI on a daily basis.

The plaster manufacturer will have a required CH range, especially during curing, for the warranty, so I again stress that you get the info from your plaster company or go online of the plaster mfg. to see what they recommend.
What type of plaster have you installed?

As we move into fall and winter, the colder water will also influence CSI calculations - just so you are aware. Here is a link to do some reading up on CSI.