Low CH in new plaster pool, should I wait it out or increase now?

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D

dandannoodles

Well-known member
Jun 30, 2020
55
Southern California
Pool Size
11000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I have a new construction in ground concrete pool, plastered with NPT minipebble on May 13th. I've brought CYA and chlorine up slowly and I've been brushing consistently (still seeing plaster dust however) and my latests tests are as follows:

CYA: 40
TA: 70
FC: .5-1.5
pH: 7.2-7.5
CH: 100-150

Should I be concerned about the low calcium hardness? Could this be why I'm still getting plaster dust? Should I add calcium carbonate or just wait longer?

I have a SWG that has not been hooked up yet and I have not yet added salt.
 
dandannoodles said:
Should I be concerned about the low calcium hardness?
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Good morning! I would be concerned that both the CH and pH are on the low end. Those two factors alone make your water more aggressive than we would like in these first critical 30 days of curing. Have you discussed this with your builder?
 
Your issue most pressing is FC. Add enough chlorine to get your FC up into the 4-6 range and keep it there.

Get FC as your priority and then you can slowly increase CH up to around 250 but stay focused on keeping your FC at adequate levels.

Your pH is in the 7's.......it's OK.
 
duraleigh said:
sing is FC. Add enough ch
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Texas Splash said:
Good morning! I would be concerned that both the CH and pH are on the low end. Those two factors alone make your water more aggressive than we would like in these first critical 30 days of curing. Have you discussed this with your builder?
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My builder is unfortunately not the type that really focuses in on pool chemistry. They basically told me their job is done after acid. They then passed me off to their pool guy friend who basically told me his plan (which did not involve testing the water) after which I decided to take over.

I've kept my CYA intentionally low due to the NPT (and other) instructions, to bring it up slowly. Which also makes it hard for me to keep chlorine in the pool. But I can bring it up if needed. I also have been following guides that my pH should be around 7.5... is that too low?
 
duraleigh said:
Your issue most pressing is FC. Add enough chlorine to get your FC up into the 4-6 range and keep it there.

Get FC as your priority and then you can slowly increase CH up to around 250 but stay focused on keeping your FC at adequate levels.

Your pH is in the 7's.......it's OK.
Click to expand...
OK, I read that I should keep my CYA and FC low after new plaster and bring it up slowly. Since my CYA has been so low it's been hard keeping the FC in the pool. It's been sunny as well lately. I will get my CYA up and FC up as well.

Do you think I need to add calcium carbonate?
 
ajw22 said:
You are past the 30 day plaster curing start up.

Where does NPT say to bring FC and CYA up slowly at this point? How slowly?


Calcium Chloride.

Calcium Hardness - Further Reading

www.troublefreepool.com www.troublefreepool.com
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OK thanks. I read that from days 4 to 28 I should bring it up slowly but you're point is well taken that I should have it up to normal levels by now.

I suppose I can also add salt now? Will salt bring up CH as well? Does it matter which I do first? Thanks for your help.
 
1 - Add enough liquid chlorine based on ypur CYA. This is the FIRST priority.
FC/CYA Levels

2 - Add Calcium Choride to get CH to about 250.

3 - If you're 28+ days past plaster, add granular CYA (stabilizer) using the sock method to bump CYA to 70.
Once CYA is in the sock and in the water, consider it added to the pool and dose FC appropriatelyfor that CYA level.

4 - If 28+ days after plaster, you can start adding the salt - but test the water with a Taylor K-1766 (or TFTestkits equivalent) salt test kit first. After testing, add about 75% of needed salt. Mix in well and allow pump to mix into the water column for 24 hours. Retest and add enough to bring salt level up to the minimum (or "slightly" higher). Mix in and again run pump for 24 hours. Retest. Once salt is at the level needed and has mixed in for 24 hours, start the SWG.

Use PoolMath and your test results to determine how much of each item above to add.

You can do multiple things - one after the other .... but getting enough FC into the water is your FIRST PRIORITY.

Fill out your signature with pool, pool equipment (including manufacturers and model numbers)and test kit(s) info.
This assists us in providing help based on your specific pool without the need to ask you each time.
 

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proavia said:
1 - Add enough liquid chlorine based on ypur CYA. This is the FIRST priority.
FC/CYA Levels

2 - Add Calcium Choride to get CH to about 250.

3 - If you're 28+ days past plaster, add granular CYA (stabilizer) using the sock method to bump CYA to 70.
Once CYA is in the sock and in the water, consider it added to the pool and dose FC appropriatelyfor that CYA level.

4 - If 28+ days after plaster, you can start adding the salt - but test the water with a Taylor K-1766 (or TFTestkits equivalent) salt test kit first. After testing, add about 75% of needed salt. Mix in well and allow pump to mix into the water column for 24 hours. Retest and add enough to bring salt level up to the minimum (or "slightly" higher). Mix in and again run pump for 24 hours. Retest. Once salt is at the level needed and has mixed in for 24 hours, start the SWG.

Use PoolMath and your test results to determine how much of each item above to add.

You can do multiple things - one after the other .... but getting enough FC into the water is your FIRST PRIORITY.

Fill out your signature with pool, pool equipment (including manufacturers and model numbers)and test kit(s) info.
This assists us in providing help based on your specific pool without the need to ask you each time.
Click to expand...
OK thank you for this. I have a TF-100 salt kit and I've been using the Pool Math app. I'll follow your guidance and report back. Thanks so much.
 
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Noodles, I don't want to be a party pooper, but we've been so preoccupied about getting some of your numbers up to normal, I thought I'd stop and ask the obvious question since your pool has been full for a while with a low FC at times. That question ..... how does the water look? Crystal clear still? No dull or hazy water? No chance at all of algae? Figured we should be sure before you get that CYA increased. It got me thinking, what if that dust you were seeing wasn't calcium but dead algae?

If the water is 100% crystal clear, no worries. Get that CYA up to 70 now. If not, or if you have any doubt about the water's condition (organics), you can do an Overnight Chlorine Loss Test first.
 
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Texas Splash said:
Noodles, I don't want to be a party pooper, but we've been so preoccupied about getting some of your numbers up to normal, I thought I'd stop and ask the obvious question since your pool has been full for a while with a low FC at times. That question ..... how does the water look? Crystal clear still? No dull or hazy water? No chance at all of algae? Figured we should be sure before you get that CYA increased. It got me thinking, what if that dust you were seeing wasn't calcium but dead algae?

If the water is 100% crystal clear, no worries. Get that CYA up to 70 now. If not, or if you have any doubt about the water's condition (organics), you can do an Overnight Chlorine Loss Test first.
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No problem, and thanks for even asking. The water has been crystal clear. The entire startup process has been a bit less than ideal... Long story short, I was traveling most of May and June due to work and I had to rely on my pool builder to keep an eye on things while I was gone. To his credit, there hasn't been algae, but as far as I know, all they did was add acid early on to acid wash the pool and then maybe some chlorine. No sequestrant was added and no one brushed the pool from May 14th when the pool was filled until June 13th, when I finally went out and bought a pool brush and started brushing it.

Since I've been back, I've made sure there was chlorine in the pool at all times, but I've just kept the levels pretty low, basically between 0.5 and 1.5 as I've slowly been raising the CYA, first to 20, then 30 and then to 40ppm last night.

I do wonder why I am still getting dust... the main drain doesn't get much suction (which I think is by design) and I don't have a vacuum (which is going to be my next step) but I've been brushing pretty much daily since July 13th and there's still dust.
 
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It sounds like you're in a unique position with a new plaster pool last year that basically sat un-brushed for the first 2 months. That's crazy. Most people are brushing like crazy for teh first few days. It would be interesting if you were able to collect any of that dust. If so, you could make a pile in the yard and put a little acid on it to see if it fizzles to confirm it's calcium.

As noted by many others above, we avoid algae by keeping the FC balanced to the current CYA as noted on the FC/CYA Levels. You may be a little cautious about the FC level, but that FC-to-CYA ratio is safe. Your FC was very low for quite some time, so I'm surprised you don't have algae, even if you don't see it via green or cloudy water. Fingers crossed it remains clear.

You seem to have a good plan forward. If you have any more questions, let us know. Lots of folks here to help.
 
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Texas Splash said:
It sounds like you're in a unique position with a new plaster pool last year that basically sat un-brushed for the first 2 months. That's crazy. Most people are brushing like crazy for teh first few days. It would be interesting if you were able to collect any of that dust. If so, you could make a pile in the yard and put a little acid on it to see if it fizzles to confirm it's acid.

As noted by many others above, we avoid algae by keeping the FC balanced to the current CYA as noted on the FC/CYA Levels. You may be a little cautious about the FC level, but that FC-to-CYA ratio is safe. Your FC was very low for quite some time, so I'm surprised you don't have algae, even if you don't see it via green or cloudy water. Fingers crossed it remains clear.

You seem to have a good plan forward. If you have any more questions, let us know. Lots of folks here to help.
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Sorry, I had the wrong date. I brushed for the first time June 13th - so it was about a month that the pool was not brushed at all.
 
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OK, thanks to everyone for their advice... I added chemicals yesterday and tested at night a few hours later. Levels are as follows:

FC: 6
CC: 0.5
pH: 7.2
TA: 70
CH: 125
CYA: 65
Salt: 400

I also went out to brush this morning and not much dust! Not sure if it's a coincidence or not.

My pool store is out of calcium chloride so I ordered from Amazon and it's coming in today. My plan is to get my CH up to 250 and then hook up the SWG this weekend and add a bunch of salt to get my salt level to 3200ish.

Any thoughts on this plan?
 
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