Rising CH: Water is only 3.5 months old.

[Yorker]

For the last month or so I’ve been reading up on TFP as to how to improve my test numbers. I must say it’s making my head spin. I thought about posting my questions on an already existing chemical/testing thread, just was not sure which one... so I started a new one.

First I want to tackle my rising CH (see attached test results). I’ve read to lower it do a partial drain and refill or Reverse Osmosis treatment on the pool water. This water is under 4 months old, and the weather has not been too hot as well, so I assume there has not been a lot of evaporation.

Our pool was re-plastered/pebbled & filed on 8/18/2018 (about 3 1/2 months ago)
The CH of our fill water was 200 (currently auto-fill water's CH is 280).

Suggestions?

Thanks,
York

PS: after this I have questions about how to keep my CSI in range - I'll post what I have tried to do and my confusion regarding that later.

 

[Texas Splash]

Yorker, with a SWG, unless you are adding any other supplemental products (i.e. cal-hypo), the CH is attributable to your local CA water and perhaps a bit of residual calcium from the curing process you had accomplished back in August. RO is available to some, but typically costly and the results are mixed. Your best offense to a high CH is to compensate by keeping the TA and especially the pH slightly lower. Those tactics will help to keep your CSI in a good place. Even with a CH of 500, it's management that way. I'd knock that pH down a bit in an effort to keep the CSI "slightly" negative. You can experiment with those numbers in PoolMath. Enter your current CH, TA, pH and water temp, then drop the pH by 3-4 points and watch the CSI. That should also help prevent scale build-up on your SWG plates. For the pH specifically, remember all of your aeration areas (spillways, jets, etc) will increase pH. Best to leave them off unless actually out at the pool.

- - - Updated - - -

Oh, and to help with evaporation - if you don't already have a cover, you might consider one. It will help retain FC and should help a bit with evaporation which in-turn should help slow autofill requirements.

 

[Yorker]

Yorker, with a SWG, unless you are adding any other supplemental products (i.e. cal-hypo), the CH is attributable to your local CA water and perhaps a bit of residual calcium from the curing process you had accomplished back in August. RO is available to some, but typically costly and the results are mixed. Your best offense to a high CH is to compensate by keeping the TA and especially the pH slightly lower. Those tactics will help to keep your CSI in a good place. Even with a CH of 500, it's management that way. I'd knock that pH down a bit in an effort to keep the CSI "slightly" negative. You can experiment with those numbers in PoolMath. Enter your current CH, TA, pH and water temp, then drop the pH by 3-4 points and watch the CSI. That should also help prevent scale build-up on your SWG plates. For the pH specifically, remember all of your aeration areas (spillways, jets, etc) will increase pH. Best to leave them off unless actually out at the pool.

- - - Updated - - -

Oh, and to help with evaporation - if you don't already have a cover, you might consider one. It will help retain FC and should help a bit with evaporation which in-turn should help slow autofill requirements.

Thanks TS!

Yes I have found keeping my pH at 7.8 is best to keep the CSI between -.3 and 0. Today I knew that my dropping the pH to 7.5 today that it would force the CSI lower. The last month or so it seems that when using pMath's calculation of how much MA to add, when I test a 2 and 4 hours later, it has not reached the target. So I lowered the target today to 7.5 thinking it would register 7.6 or 7.7... oddly today it the target spot on, unfortunately it dropped the CSI to the -.46! Hmm same jug of MA.

Pool School suggests: The acid/aeration process to lower TA:

1. Add acid to lower your PH to between 7.0 and 7.2 (this also lowers TA)
   
2. Aerate until PH rises to around 7.6 (the only way to raise PH without also raising TA)
3. Repeat steps 1 and 2 until you reach the desired TA.

If I lower my pH to 7.2 that would lower my CSI to -.73 and hopefully lower the TA to 60, then run the pump to use the spa spillways to add aeration. That will raise the ph but not the TA ... right? How long might I need to run the pump at 2700 rpms?

Also, I think my salt cell has had very little build up. Here's a link to photos I posted in another thread.

 

[Texas Splash]

You have the TA lowering process correct. Aeration does increase pH while leaving the TA low. In the end, try not to get too wrapped-up in a specific number. We all go nuts trying. You know the recommended ranges and have an understanding of CSI, so simply use PoolMath to manage those numbers throughout each season. Even if one number drops or spikes for some reason, it takes many weeks to see negative results one way or the other, so try not to let it get to you. Some pools simply operate better with a pH on the higher end of 7s, and some like a TA low while others slightly elevated. So you'll have to play with it a bit to find the "sweet spot". Your challenge will be the ever-increasing CH which will require the lower pH and TA over time. But with proactive management, as you are doing now, you'll be a step ahead of things. Even at some point the CH may grow to the point you have no choice but to do a good water change, but you'll prolong those events by being in control of your water chemistry. Stay with it and let us know if you have any other questions.

 

[aussieta]

start collecting rain water and use for pool top ups
i just looked where cathedral city is, that may not be practical
maybe a water softener

 

[Yorker]

start collecting rain water and use for pool top ups
i just looked where cathedral city is, that may not be practical
maybe a water softener

Yeah, not too practical... even with fingers and legs crossed When it does rain here, it generally (but not always) is a REALLY good amount. The last good rain added almost 3". That may happen a few times a year.

 

[Yorker]

Update,today my numbers were
FC: 6.0
CC: 0.0 (2 days ago)
pH: 7.8
TA: 70 (2 days ago)
CH: 570
CYA: 70 (2 days ago)
Temp: 56°
CSI: .10

So I added MA to lower my pH, which should also lower my TA and CH.
4 hours later my numbers are:
FC: 6.0
CC: 0.0 (2 days ago)
pH: 7.2
TA: 50
CH: 550
CYA: 70 (2 days ago)
Temp: 56°
CSI: -.89

So the goal was to lower my CH, which it did - but not by very much, and really lowered the CSI - yikes!. Sometimes before adding my chemicals, I use pMath as a preliminary calculator to see how raising/lowering pH, CYA will effect the CSI, but is there a way I could have used pMath to know how much of an impact lowering the pH to 7.2 would have on the TA?

If I let the pH rise back to 7.8, then keep lowering it to ... say 7.5 over time will that keep lowering the TA as well as the CH?

I'm conflicted. Is having CSI lower than -.3 worth it if it takes a month (or more) to lower the CH to an acceptable level?

Also, now that my TA is too low - should I add baking soda now, or wait a while?

Thanks in advance!

 

[ajw22]

TA 50 is ok and it can bounce back. Dont lower your PH to 7.2 again. Let your PH drift up to 8 then lower it to 7.6. The lower the PH, the more TA is affected.

PoolMath at the bottom “Effects of adding chemicals” will give you an estimate of PH and TA change for adding an amount of MA.

Adding MA does NOT change CH. Only way to reduce CH is draining the pool or a reverse osmosis process.

I suggest you slow down and not tinker so much with the water.

 

[Texas Splash]

Yorker, I want to make sure I understand what you were trying to do here:

So the goal was to lower my CH, which it did - but not by very much, and really lowered the CSI - yikes!.

Did you exchange water, or just add the acid? You also said this:

I use pMath as a preliminary calculator to see how raising/lowering pH, CYA will effect the CSI,

So remember, your CSI will be most effected by pH, TA, CH, water temp, and in your case …. salt. The CYA is not a big player. So make sure when you are looking at PoolMath to pay close attention to those items. You can experiment all you want in PoolMath before actually adding the chemicals.

As you can see from your first set of numbers (2 days ago), your CSI was in decent shape (slightly positive). While the pH may be on the upper end of the 7 scale, the CSI was still "slightly" positive because the cool water is working in your favor. It only needed a little chemical help to get to the negative side. But as soon as you hit it with acid - boom. The CSI dropped, and it took some TA down with it. So let the pH climb again since it will have the quickest effect on getting your CSI back to between -0.3 and zero. Go easy and let the pool settle a bit to find that sweet spot. You'll get it.

 

[Yorker]

PoolMath at the bottom “Effects of adding chemicals” will give you an estimate of PH and TA change for adding an amount of MA.

Thanks Allen. I'm looking at pMath (mobile app) and can't seem to locate “Effects of adding chemicals” at the bottom of any page. Can you direct me to where I can find it.

 

[ajw22]

Thanks Allen. I'm looking at pMath (mobile app) and can't seem to locate “Effects of adding chemicals” at the bottom of any page. Can you direct me to where I can find it.

You have to get on the website and use PoolMath there to find it. It is not on the app yet.

 

[kingstar]

Just getting started myself, but I believe the "Effects of Adding" is in the mobile app.

 

[Yorker]

Just getting started myself, but I believe the "Effects of Adding" is in the mobile app.

Thanks kingstar, right there under my nose!

... let the pH climb again since it will have the quickest effect on getting your CSI back to between -0.3 and zero. Go easy and let the pool settle a bit to find that sweet spot. You'll get it.

Pat, I did not replace any water, only added the MA and I have been paying the price for my aggressive MA addition. I have not added any MA since and my pH today is up to 7.7, unfortunately the CSI is raising very slowly (today -.57, up from -.62 two days ago. I'm running the spillways for about 5 hours a day at 2700 rpms to aerate the water and raise the pH a bit faster and hopefully get the CSI above -.3. After the pH hits 8.0, I can dose it to 7.7 or 7.8. I have no problem monitoring it daily.

Will it be ok if it takes 5 or more days to get the CSI above -.3?

 

[ajw22]

Will it be ok if it takes 5 or more days to get the CSI above -.3?

Yes, it is okay. Out of range CSI takes weeks or months to have bad effects. A few days out of range is not a big deal.

 

[Yorker]

Yes, it is okay. Out of range CSI takes weeks or months to have bad effects. A few days out of range is not a big deal.

Thanks Allen.

I was looking at your signature. Your plaster lasted 17 years ... that sounds great.

 

[ajw22]

I was looking at your signature. Your plaster lasted 17 years ... that sounds great.

It was only due to a rust spot in the deep end of the pool caused by rusting rebar that I redid the plaster. The plaster was getting a bit rough in teh spa but otherwise was fine.

I had the plaster redone by the company that built the pool.