Ph after water softener First readings

[kul]

Then I don’t know why my pool guy adds additional cya in summer if the level is not affected by replacement of water over time due to evaporation. He also seemed to imply that this water addition over months causes the Cya to decrease

 

[Donldson]

I don't know why someone would do that or believe that either, but it doesn't. Evaporated water is distilled water, meaning it does not carry dissolved solids. CYA, calcium, salt, all of this is left behind when water evaporates.

 

[kul]

I don't know why someone would do that or believe that either, but it doesn't. Evaporated water is distilled water, meaning it does not carry dissolved solids. CYA, calcium, salt, all of this is left behind when water evaporates.

What about the new water that I add in each week? (About an inch or inch and a half). Doesn’t adding that affect the CYA and the CH since it is just regular water from a hose?

 

[Donldson]

Doesn’t adding that affect the CYA and the CH since it is just regular water from a hose?

No and yes. When water evaporates it leaves behind the CYA and CH, so the concentration is raised. Then when you replace the evaporated water it is diluted back to the original levels . That's completely true for CYA, but CH is different because the water you are adding has calcium so it rises over time.

 

[kul]

Best to get that CH lower ASAP - or the whole pool will have scale in it, quite soon. If you get rain this winter, drain off as much water as you can and refill with rain water. Use pool water for landscape watering and refill. If you have a water softener, use softened water to refill the pool.

No and yes. When water evaporates it leaves behind the CYA and CH, so the concentration is raised. Then when you replace the evaporated water it is diluted back to the original levels . That's completely true for CYA, but CH is different because the water you are adding has calcium so it rises over time.

Aha. Ok that makes sense. Then it sounds like some level of draining is going to be needed at some point. It was mentioned to maybe use it for landscaping, but would t the chlorine and etc kill off all the plants?

 

[mknauss]

When adding liquid chlorine, if the recommended addition is 1.7 gallons, is it a big deal to just put 2 gallons?

As long as the resulting FC is at or below SLAM Process level, it will not matter.

 

[kul]

Another question- if draining a plaster pool are there any things I should keep in mind? I saw some photos of pools cracking when drained so am not sure if that is a concern with this plaster pool.

 

[mknauss]

Another question- if draining a plaster pool are there any things I should keep in mind? I saw some photos of pools cracking when drained so am not sure if that is a concern with this plaster pool.

There are risks. I doubt you have shallow ground water so popping the pool is very unlikely. If drained in cool, low sun angle times of the year the plaster has less chance of failure. But it is not risk free. In your area, with high water costs, reverse osmosis may make sense. It would remove both the CYA and CH.

 

[kul]

There are risks. I doubt you have shallow ground water so popping the pool is very unlikely. If drained in cool, low sun angle times of the year the plaster has less chance of failure. But it is not risk free. In your area, with high water costs, reverse osmosis may make sense. It would remove both the CYA and CH.

This does give me pause. A half drain would be risky then? Maybe instead I can do a few partials over time. Like take it down 6-7 inches and fill and then see how it goes? I have no idea how much a reverse osmosis in LA costs, but wouldn’t be surprised if it’s outrageous.

 

[mknauss]

The issue with small drain is you will use a lot more water to achieve the end result.
The RO process is not cheap, but if you do a number of small drains, it may be cheaper than the water.

 

[kul]

The issue with small drain is you will use a lot more water to achieve the end result.
The RO process is not cheap, but if you do a number of small drains, it may be cheaper than the water.

If I drain half the water do you think I’d be able to avoid Plaster damage? That’s a huge concern. The pool is about 5 years old so I don’t plan to replace plaster anytime soon.

 

[mknauss]

I doubt there is a big risk, but the risk is not zero.

A half drain will help the CYA level. It will only reduce the CH level by a little as your fill water has significant CH. Unless you have softened water available.

There is an exchange process described in Draining - Further Reading

 

[kul]

I doubt there is a big risk, but the risk is not zero.

A half drain will help the CYA level. It will only reduce the CH level by a little as your fill water has significant CH. Unless you have softened water available.

There is an exchange process described in Draining - Further Reading

I think you are right. It would probably only help the CYA issue. We have hard water so maybe that’s just life. I’d hate to replace water and then still have high CH

 

[kul]

The no drain water exchange sounds promising and unlikely to cause plaster damage

 

[Rancho Cost-a-Lotta]

Last time I checked a couple years ago, RO service in our area cost about $600-$700. Water fees are minimal compared to RO. Even at the highest tier, I can refill my pool for less than $70.

If you decide to drain, consider scheduling it when rain is expected. The rain will keep your plaster moist to avoid damage. You'll also take advantage of some calcium-free fill water.

Not sure how your water company calculates sewer rates, but some providers base sewer rates on water usage during two billing periods per year. If your provider does this, make sure you don't exchange water during one of those months.

My fill-water CH is 100-125, similar to yours. With evaporative top-offs, I see an increase in CH levels of 125-150 per year. I recently installed an RV water softener (@mknauss uses one too) hooked up to my fill line. My fill water CH is now less than 10 ppm. I use a larger softener that only requires regeneration every 3-months or so. This should effectively freeze my CH at it's current level which means no need for future water replacements.

 

[kul]

The rain will keep your plaster moist to avoid damage.

This is helpful. I might try this in addition to filling at the same time I am draining.

 

[kul]

First, I apologize for my excessive questions. Second, I have another question - how do I calculate TDS? (In reference to the below regarding exchange process):

Pool Water TDS (PWTDS)
Pool Water Temperature (PWT)

Fill Water TDS (FWTDS)
Fill Water Temperature (FWT)

DeltaT = (PWT - FWTDS * 0.006) - (FWT - FWTDS * 0.006)

If DeltaT is positive, then you want to fill at the lowest point and extract at the surface and at the greatest distance from the lowest point.

If DeltaT is negative, then you want to extract at the lowest point and fill at the surface and at the greatest distance from the lowest point. <-Preferred as it is easier to do with a drain pump and you can fill inside one of the skimmers.

If |DeltaT| < 5, then there will be a lot of mixing.

 

[mknauss]

TDS is essentially your CH plus CYA plus salt. There is some other items, but they are minor.

You may have to get a salt reading from a pool store.

 

[kul]

TDS is essentially your CH plus CYA plus salt. There is some other items, but they are minor.

You may have to get a salt reading from a pool store.

Since mine is not a salt pool would I still need to test for that?

 

[mknauss]

You may be surprised at the salinity of your pool water. Liquid chlorine, trichlor, dichlor, muriatic acid, body fluids, all contain salt.

Up to you, but it is wise to get it tested, especially if your pool water and fill water temperatures are very close. If 20F difference, not as big a deal.