New Gunite/Plaster Pool Water Chemistry

[Steve-D]

Greetings all. For some background I am including a link to my New Pool Build post. The pool is not yet 100% done but we are told it's swimmable so we're working on getting the water chemistry in balance. Chlorine levels will be maintained manually until the SWG comes online in 1 or 2 weeks (planned for Memorial Day weekend). My most recent test results are below:.

FC 5.0
CC 0.5
PH 7.5
TA 100
CH 210
CYA 0

Cl was only added for the first time last night and at time of testing the pool had seen no meaningful direct sunlight. It's sunny now so I expect the Cl to drop given the absence of stabilizer. The pump has been running 24x7 at low speed and there were still some leaves in the skimmer baskets, we only vacuumed for the first time yesterday all of which I take to explaining the CC level. I'm waiting on recommendations from the PM for the installers but given the TFP philosophy I wanted to get some feedback here, too.

1. With the plaster is still curing should I be aiming for a higher CH (but still in the 200-400 range)?
2. Do I need to bring up the CYA level and if so what should I use? It's a 20,000 gal pool.
3. If yes to #2, what should be my target CYA level?

From what I read for a SWG system the CYA range s/b 60-80 and for a Cl system the CYA range s/b 40-50...does that mean I should aim for the low end (40-50) knowing that in a few weeks we will be cutting over to the salt system? I don't want to screw up the balance for when the SWG comes online.

And FYI, my wife is taking the pool installers word as gospel. This is not our first pool but it is our first plaster and SWG pool so for now were back to being beginners. I know that there is a different TFP perspective and that's something I want to move towards once my comfort level is up with the new equipment.

Thanks in advance!

[edit to clarify as CYA level ranges for SWG vs Cl system]

 

[IceShadow]

Does your builder have requirements for chem levels to maintain your warranty? I'd stick to those, doing what you can to follow TFP methodology at the same time, but I'd hate for you to have some sort of issue and be denied your warranty because you weren't keeping within levels they require (even if it had nothing to do with the issue).

FC should NOT be 40-50 - that's really high. Did you mean something else for Cl?

I'll let others answer the rest as I'm not as familiar with new plaster pools.

 

[Steve-D]

Does your builder have requirements for chem levels to maintain your warranty? I'd stick to those, doing what you can to follow TFP methodology at the same time, but I'd hate for you to have some sort of issue and be denied your warranty because you weren't keeping within levels they require (even if it had nothing to do with the issue).

FC should NOT be 40-50 - that's really high. Did you mean something else for Cl?

I'll let others answer the rest as I'm not as familiar with new plaster pools.

FC is 5.0 , not 50.0, so it is just a bit high and is expected to come down with sunshine. FWIW, I did the Cl Drop test with the T-100 kit...Installers provided a Taylor K-2005 and that's what we have been using.
Excellent point with regards to water chemistry balance and warranty...I will get that clarified and their terms will drive the target levels.

 

[IceShadow]

At a minimum I would add stabilizer to get CYA up to 30 to start. CYA of 0 means your FC is really harsh and will burn off in the sun super fast. I recommend dry stabilizer/CYA added via sock method. (Put it in an old sock/stocking, tie it off, dangle it in front of the returns, squeeze every now and then to help it dissolve.)

 

[Steve-D]

Updated (5/16/2022, 4:30 PM) test results are below:

FC 3.5
CC 0.5
PH 7.4
TA 100
CH 210
CYA 25

I added another 4 lbs of stabilizer, some to skimmer and most to "socks" in the two skimmers. I am hoping/expecting the FC level to continue to drop closer to a good range and will check on Chlorine and CYA levels later today. We had some rain and wind last night leaving a pile of debris on the surface so I hand-skimmed a good amount of it to start the day. It will get another skimming and brushing end of day.

 

[ajw22]

You should be following a Plaster Startup Guide for the first 28 days. The water chemistry on startup is different then normal pool chemistry. Transition to Recommended Levels after 28 days.

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

Salt should not be added for 30 days and so SWG cannot be used.

 

[ajw22]

Plaster Installation and Maintenance - Further Reading

www.troublefreepool.com

When Should Salt be Added? In our industry, there seems to be some consensus to wait 30 days before adding salt to new plaster pools, yet some say it is okay to add salt within a couple of days of filling the pool. Who is right? This thread describes why it appears that the recommendation to wait 30 days before adding any salt is appropriate for most plaster pools, including quartz and pebble pools

 

[Steve-D]

Thank you for the article links, @ajw22 . Per the recommendations from the PM for our installer only the Chlorine and CYA levels are out of whack and we are moving towards getting them in balance. I just added 4 lbs of stabilizer this morning and if the first 4 got us from 0 to 25 then the addition should get us closer to 50 . At that point we'll look at another 4 lbs (ish) to get us closer to their target of 80. Our PM is saying FC @ 1.5 ppm should be good but we're aiming for 2.0...and with sunshine and low CYA levels we expect the FC levels will continue to drop from <yesterday's> 3.5 closer to our target.

We're not expecting to be able to turn on the heater or to switch to the SWG until Memorial Day weekend and so it will all be manual <liquid> chlorination between now and then.

 

[ajw22]

Thank you for the article links, @ajw22 . Per the recommendations from the PM for our installer only the Chlorine and CYA levels are out of whack and we are moving towards getting them in balance. I just added 4 lbs of stabilizer this morning and if the first 4 got us from 0 to 25 then the addition should get us closer to 50 . At that point we'll look at another 4 lbs (ish) to get us closer to their target of 80.

I think that is an unnecessary amount of CYA for the first 30 days.

A CYA of 30-40 is all you need since you should not be adding salt or running your SWG.

After 30 days you can bring up your CY and add salt. Although 80 ppm of CYA is not needed in Boston teh way it is in Texas or Arizona. I think 60-70 CYA would be fine.

Our PM is saying FC @ 1.5 ppm should be good but we're aiming for 2.0...and with sunshine and low CYA levels we expect the FC levels will continue to drop from <yesterday's> 3.5 closer to our target.

That is where I would run your FC more in the 2-3 ppm range. You don't want to chance getting an algae problem in new water with new plaster. Better to keep the FC around 3 ppm.

 

[Steve-D]

Thx again for the feedback. I thought their CYA target of 80 seemed high, too. If this last batch of stabilizer gets us to 50ish I'm happy with that unless the Installer starts throwing warranty concerns at us for not following their advice.

While this is our first IG/Plaster pool it is not our first pool so I'm very leery of adding chemicals that can only be adjusted down by removing/replacing pool water (hence the slow going with adding stabilizer).