Two-week vacation in July

[Mitchum]

We'll be leaving for a 2-week vacation in July. I typically keep the pool at:

FC: 5ish
pH: 7.5 to 7.8
TA: 60 to 70
CYA: 70
Salt: 3000

We have a SWG, so keeping the FC level where it needs to be isn't a problem. What I'm worried about in rising pH.

My pool typically goes from 7.5 to 7.8 in 2 days, so I add 12 oz of MA every 2 days. The plaster was redone about 8 months ago (before we bought the house). There is also a spillway from the spa to the pool, but I try to have the water trickle down as opposed to having a major spill (and aerating the pH back up).

What is the best way to keep the pH within safe levels while we're gone? I've been thinking about adding borates, which is supposed to help with pH rise. I read at least one post where someone had this same issue of raising pH and borates didn't solve the issue.

Any ideas on what to do while we're away?

In addition, I am away for work a week at a time and I don't think my wife will be comfortable handling MA. Is there something easy she could do to keep the pH in check while I'm gone?

Thanks!

 

[JohnT]

What is your TA?

 

[JasonLion]

By adding borates, lowering the TA to 50, and minimizing use of the spillway, you should be able to get the PH stable enough. While this hasn't worked for everyone, to does work for the great majority of people.

Of course, even if you do get the PH to stabilize, leaving the pool alone for two weeks is something of a gamble. It isn't likely, but a major storm early in your trip could easily cause problems.

 

[Mitchum]

As mentioned in the original post, I try to keep it between 60 and 70. It's 60 at the moment.

 

[Bama Rambler]

You can lower your TA a little and that should slow the pH rise down a bit. Jason beat me here!

She could use dry acid if she's afraid of using Muriatic acid.

 

[Mitchum]

By adding borates, lowering the TA to 50, and minimizing use of the spillway, you should be able to get the PH stable enough. While this hasn't worked for everyone, to does work for the great majority of people.

I have some time between now and July, so I have time to dial all of this in. That will give me time to see how the pool chemisty works with the borates.

Should I strive to keep TA around 50 at all times instead of the suggested level of 60 to 70 for an SWG pool? Or just when I plan to be away for a while?

Should I drop the pH to something below 7.5 just before leaving? How low is considered safe assuming no swimmers? Again, I have time to dial this in and borates (and a lower TA) may stabilize things by itself.

BTW, I have to use the spillway to keep the chemistry balanced between the spa and pool. I usually have the spillway run for the 2-hour cleaning cycle and not at all when running the pump at a slower speed for 5 more hours. I can adjust the pool/spa return to slow the spillway down even further to a small trickle because now it may be a bit high. It takes a bit of work to dial it in because if the flow to the spa return is too low, there isn't enough pressure to open the check valve. This check valve is needed to keep the spa from draining back into the pool which is about 5 feet below the pool and the pump.

 

[Mitchum]

OK. I still haven't added borates yet. I continue to add acid every other day or so but the TA seems to stay stable even though I'm not adding anything to bring it back up. So this morning, I brought pH down to 7.2 (I typically only bring it down to 7.5). Prior to that, here were my measurements:

FC: 3.0
CC: 0.5
TC: 3.5
pH: 7.8
TA: 70 to 80
CH: 575
CYA: 55
Salt: 4200

After adding acid, my measurements were:

pH: 7.2
TA: 60 to 70

I typically measure pH every day but TA once every other week or so. I'll keep an eye on TA to see if I can get it down to 50 to see if things stabilize pre-borates.

I still have two unanswered questions:

Should I strive to keep TA around 50 at all times instead of the suggested level of 60 to 70 for an SWG pool? Or just when I plan to be away for a while?

Should I drop the pH to something below 7.5 just before leaving? How low is considered safe assuming no swimmers?

 

[jblizzle]

I would say lower the TA to 50 now and see how your pH behaves for the next month.

If you use the poolcalculator, you can input your levels and at the bottom see the CSI ... you want to keep this between -0.6 and +0.6. pH is a major driver of CSI so given you levels you can see how low of a pH would keep your CSI in range.

Given what you just posted above, I have your CSI at -0.62 so you are on the edge of the safe level. If you drop your TA to 50, you would not want your pH to be below 7.4

One thing I find interesting and maybe someone can comment, but using the above levels and a TA = 50 it seems that the pH could go up to 8.5 and still be at a CSI of +0.49 (supposedly safe). Although many times we say never let pH go above 7.8 ... is there a different reason for that besides the CSI?

 

[Mitchum]

I was out of town for a week. When I came back, my pH was above 8.2. I lowered it to 7.5 and measured my TA. For some reason, my TA climbed up to 90 while I was gone (it was 60 to 70 before I left). Is this common? It's taking me quite some time to get it down to 50...

 

[faby3003]

Its common for tap water to be high in TA. Have you added any water to the pool during this time?

 

[Mitchum]

My pool was about an inch low so I did add some water but it couldn't have been more than 200 gallons...

 

[Mitchum]

Plus, I add about 8 oz of MA every other day to keep pH in the 7.8 to 7.5 range, so I'm surprised that my TA isn't much lower...

 

[faby3003]

The TA of my fill water is around 200 ppm. When I add even just an inch of fill water to my pool, I see a 10-20 ppm increase in TA.

 

[Hub]

What caused your CYA to drop from 70 to 55 during the past month? I would assume rain and adding water?

 

[Mitchum]

What caused your CYA to drop from 70 to 55 during the past month? I would assume rain and adding water?

Yes, I added about an 1" to 1.5" of water. I've started adding conditioner to bring it back up. Why do you ask?

P.S. I live in San Diego. It doesn't rain here...

 

[Hub]

What caused your CYA to drop from 70 to 55 during the past month? I would assume rain and adding water?

Yes, I added about an 1" to 1.5" of water. I've started adding conditioner to bring it back up. Why do you ask?

Just curious really. I'm a noob at this and am under the impression that CYA is quite stable so I was a bit surprised to see yours move that much in only a month under normal conditions.

ETA: Sorry if a bit off topic.