Should I Target a Lower CH Level?

[ShallowWater]

We've been getting a lot of rain, er, atmospheric rivers, here in SoCal since December.

Here are my test results.

Free Chlorine: 5.0
Combined Chlorine: 0.0
pH: 8.2
Total Alkalinity: 110
Calcium Hardness: 225
CYA: 80
Salt: 3000
Temperature: 68°F
CSI: 0.26

I know I need to drive down TA and pH but what about CH? I've been targeting 300 but the csi is already at the high end of the range so maybe 200 to 250 is a good target with slightly elevated TA and pH?

As a note my auto fill is connected to my water softener so I figure supplemental Calcium Carbonate will be necessary from time to time but it is better to manage this way than to drain the pool. Filling to the overflow from God's teardrops the last 3 months is most likely soft water too I think.

What do the experts here think?

 

[YippeeSkippy]

Using the older version of PoolMath I entered in all your current levels....then tweaked. Current in left side column and tweak in the right side. You *need* calcium so I wouldn't drop it. Take your pH down with MA and let it work on lowering your TA too.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

Maddie

 

[ShallowWater]

So I should target a higher Calcium Carbonate level and get my pool more on the base side vs acidic side. I'll adjust and report back after the current atmospheric river passes through.

 

[Newdude]

Freak weather notwithstanding, it will end eventually. I'd let it drift down as the floods continue and add back to 350 when it dips below 300.

 

[YippeeSkippy]

Your pool pH needs to be in the 7s. With a salt cell the device often likes to hover around 7.8ish, so that's an easy tweak. With your TA so high it is "pulling" the pH up and will do so repeatedly as long as the TA is high.

Since you have been draining water with all these "atmospheric rivers" you want to be assured of having enough calcium in the water that it doesn't get leached out from the plaster itself. Tweaking that just helped make your CSI a bit prettier.

Focus on the pH and TA first, and see if that improves things. You want to be as close to "zero" CSI, or slightly negative.

 

[proavia]

Drop your pH down to 7.2 and allow to rise to 7.8 - this will help drive down the TA.
Try to keep CSI slightly negative - in the 0.00 to -0.30 range. This will help minimize calcium buildup in the SWG.

With the rain, you are getting quite a bit of aeration. Stay on top of the pH as aeration will cause the pH to rise.

Use the old PoolMath page linked above and play around with the pH, TA and CH numbers to see the effects.

 

[ShallowWater]

I added a quart and a half of MA and aerated at lunch today but did not have time to test. Trying to push pH to low 7's and TA down to the 80's. Looking at the math, if I raise the CH to 250 I will need nearly 3 lbs of Calcium Carbonate and will push my pool to the acidic side with a csi of -.28. It almost seems I need to add a bit more Calcium Carbonate given my fill water is Calcium Free.

 

[YippeeSkippy]

Slightly negative is fine.

 

[ShallowWater]

Drop your pH down to 7.2 and allow to rise to 7.8 - this will help drive down the TA.
Try to keep CSI slightly negative - in the 0.00 to -0.30 range. This will help minimize calcium buildup in the SWG.

With the rain, you are getting quite a bit of aeration. Stay on top of the pH as aeration will cause the pH to rise.

Use the old PoolMath page linked above and play around with the pH, TA and CH numbers to see the effects.

As my fill water has no Calcium it will not rise due to evaporation and when we start using the pool it may actually drop due to water being removed from the pool by means other than evaporation because there will be no new Calcium added from the fill water. In this case I don't think calcium build up will be a problem in the SWG but I will bring csi in the negative acidic range. Thoughts on this goal?

 

[ShallowWater]

Oops, 84* is probably where it will be in a couple of months given it is only 4 feet deep..
For the temp at 70* the csi is a bit lower but still in range:

 

[proavia]

See how only adjusting the pH bought the CSI slightly negative - without a calcium increase?
Even with water temp presently at 70 and increasing soon to 84, your CSI is still slightly negative.
For now, you're good. You may (or may not) have to increase calcium in the future. Just test CH at least monthly to see how your numbers are doing.

Also, shoot for the high end of the target range for FC - or even a couple ppm higher. This will provide more of a buffer for heavy bather load days or increased FC needs as the temps warm up.

If you drive the pH down to 7.2, it will have the biggest effect on TA. As your present TA is 110, your pH will rise pretty quickly. During this process, don't be concerned with a CSI a bit out of range. Having CSI out of range isn't a big deal if for a week or so.

If you change the TA in your prsent numbers from 110 to 80, notice how it changes the CSI.

 

[ShallowWater]

See how only adjusting the pH bought the CSI slightly negative - without a calcium increase?
Even with water temp presently at 70 and increasing soon to 84, your CSI is still slightly negative.
For now, you're good. You may (or may not) have to increase calcium in the future. Just test CH at least monthly to see how your numbers are doing.

Also, shoot for the high end of the target range for FC - or even a couple ppm higher. This will provide more of a buffer for heavy bather load days or increased FC needs as the temps warm up.

I totally agree with this response! These aren't actual test numbers of course but are what I'm shooting for but you probably new that already. With a SWG it will be hard to keep pH below 7.8, nevermind 7.5. I've done this dance before with my previous pools. Keeping TA below 90 also becomes a chore. In my previous pools I've kept FC up around 7 or so but over the winter the pool's been 50* to 60* and a lower FC was fine. Now that spring has sprung and the temps are going up it's time to start paying attention. I think I need to turn up the Cl output from my SWG a notch. Thanks for bringing it to my attention.

 

[ShallowWater]

I know my thread is about CH but what's a good InteliChlor setting? Previously I had a Hayward SWG set around 50% IIR but the InteliChlor at 50% Pool / 20% Spa is giving me lower FC values.

 

[proavia]

You will need to adjust your SWG according to your needs. If 50% isn't high enough, either increase the percentage or increase the pump runtime.

My fill water pH averages 7.8 and TA is 100-120. I can maintain a pool water pH of 7.6-7.8 and a TA of 60 (once I drive the TA down) pretty easily with only weekly or less acid additions. I'm in Arizona and have high evaporation in my dry climate - higher evap than in Riverside.

 

[ShallowWater]

You will need to adjust your SWG according to your needs. If 50% isn't high enough, either increase the percentage or increase the pump runtime.

My fill water pH averages 7.8 and TA is 100-120. I can maintain a pool water pH of 7.6-7.8 and a TA of 60 (once I drive the TA down) pretty easily with only weekly or less acid additions. I'm in Arizona and have high evaporation in my dry climate - higher evap than in Riverside.

Do you add MA to 7.2 and aerate each time?

 

[Texas Splash]

Do you add MA to 7.2 and aerate each time?

You can. If your TA is a bit elevated and you are trying to lower it, use enough MA to lower the pH to about 7.2. From there you can try to aerate the water to increase the pH faster, or just the pH rise on its own. Just depends on how fast your pH rises. Once the pH hits that 7.8-8.0 range, hit it with acid again to knock it down to 7.2. Each time you do that it should help to lower the TA a bit.

 

[ShallowWater]

You can. If your TA is a bit elevated and you are trying to lower it, use enough MA to lower the pH to about 7.2. From there you can try to aerate the water to increase the pH faster, or just the pH rise on its own. Just depends on how fast your pH rises. Once the pH hits that 7.8-8.0 range, hit it with acid again to knock it down to 7.2. Each time you do that it should help to lower the TA a bit.

I think I'll do this and see how it goes. I've probably been driving the pH up via aeration unnecessarily.

 

[ShallowWater]

I think a bit of aeration may be necessary.

FC: 5.0
CC: 0.0
pH: 7.2
TA: 90
CH: 225
CYA: 80
SALT: 3000
T: 62°
CSI: -0.87

 

[ShallowWater]

And I should probably push my CH to 350..

 

[reggiehammond]

I would wait until the rain stops. Your CH is just fine for the time being.
No reason to dump more CH with knowledge you'll be overflowing more soon.