Parents on vacation - taking care of pool that's in trouble

[wes8398]

I have my own pool opened up, balanced, and in use; but I volunteered to take care of my Mom and Step-Dad's pool while they're away for 3 weeks. They use a "kit" with tri-chlor pucks and weekly packets of shock (labels don't state what exactly the stuff is - just says "S.W.A.T. clarifyer and oxidizer"), the same one I USED to use before finding the BBB method here. I basically need to get everything in check so I don't have to be over there multiple times a day for the next 3 weeks.
Here's a quick background. Step-Dad's been fighting phosphate "problems" (against my recommendations) since he opened the pool 2 weeks ago. He just finished his 3rd phosphate "treatment", vacuumed out all the Crud, and left me with pretty clear looking water. Last night, after hearing him talk about the phosphate problem, I told him to add 10 litres of chlorine (12.5%). This afternoon I went over and added another 10 litres. Then I brought my TF-100 over there tonight and discovered the following:

FC - 1
CC - 9.5
pH - 7.2
TA - 80
CYA - ~10
CH - un-tested

Other info on his pool: ~23,000 gallons, vinyl liner, sand filter

So, from the CC reading, I'm inclined to think he's got an algae problem happening and that I've got to shock, shock, shock ... right? With CYA so low, is a 10ppm shocking level ok? Or would it be advisable to go higher? Also, how often do you think I'll have to be over there adding chlorine to take care of the 9.5 CC? And how long would you estimate I'll have to hold shock level?
Any other tips/advice would be welcomed as well!! Thankfully I've not had to tackle an algae problem with my pool, but I'm obviously going to have to learn how to with the parent's pool. Once that's taken care of, hopefully I can pretty much leave theirs to the "kit" they use and be able to enjoy more of my algae-free BBB pool

 

[Richard320]

I think I just read something here today or yesterday that Monopersulfate can give a false CC reading. That's a common "Non-chlorine Shock" sold in pool stores. Use the search box, maybe it will come up for you.

 

[PaulR]

I found a thread from last year that mentioned this SWAT stuff
little-bit-confused-about-what-to-do-next-t14633.html
but no real info on what's in it. Google (outside of TFP) came up empty.

With a CYA of <=10, shock level would be FC 10. If SWAT does contain MPS and that's why the CC is elevated, then I believe it would clear up in a day or two. But, again with such low CYA, you will lose the vast majority of your FC to sunlight; so best to start the shock process in the evening, and carry on as late as you're willing to go.

It is mildly surprising to see CYA so low given the use of trichlor. You did that test with your back to the sun, not with the view tube in direct sunlight?
--paulr

 

[wes8398]

It is mildly surprising to see CYA so low given the use of trichlor. You did that test with your back to the sun, not with the view tube in direct sunlight?
--paulr

There was no direct sun when I tested. I filled the vile completely and could still see the black dot quite clearly. And he's been using this kit for the last 4 years or so, too! With no major draining/refilling - just weekly backwashing, and then recently vacuuming/wasting the phosphate remover sediment. I was expecting quite a high CYA reading too.

Anyway...I don't think any of the SWAT has been added for a couple days. That coupled with the "phosphate fight" he'd been going through makes me inclined to think he's got an algae problem looming. It wont hurt to shock, so that's what I'm going to do through the day today, or tonight. You all think 10ppm shock level is good (as per the calculator), or would it hurt to go higher?

Thanks!

 

[dmanb2b]

If the CC reading is really that high, I'm almost suspecting a CYA to ammonia coversion over the offseason....in which case will take a lot of chlorine to take care of the ammonia. Either way, if you find the cc reading to be accurate, you should start beaking it down by using liquid chlorine and trying to reach shock level. Also add 30 ppm of CYA at you earliest convenience. You can assume your CYA is zero, based on the above description.

 

[wes8398]

Ok, this is strange. It probably sounds like I did something wrong in my testing last night, but I'm SURE I didn't. Anyway, I bought 40 litres of chlorine and brought it over there this morning; ready to start shocking the Crud out of the pool. Before I commenced, I thought I might as well check levels again. Low and behold, testing showed FC level of 3.5 and a CC level of 0 (or maybe 0.5)!! Huh ... So, I added a few litres to bring FC up to 6ppm and also threw a sock full of CYA into the skimmer and left. I'll be going back tonight to test again.

 

[frustratedpoolmom]

Keep us posted...

Did you go to the wrong house? LOL

 

[wes8398]

Testing = another different story tonight

LOL - I'm pretty sure I was at the right house!

So, tonight I went back and tested again around 10pm. This time results were less than 1 FC, and 3 CC. I added enough 12% chlorine to bring FC up to about 10 overnight and I guess I'll test again in the morning sometime.
Anyway...any suggestions on what's going on with my Parent's water? Last night, when I got the 9.5 CC reading, it had rained pretty hard that day, and the sun had been set for some time before I tested. I hadn't replenished his chlorine stocks yet, so NO chlorine was added at this time and it sat overnight. Then this morning, I had the 0 CC reading, the sun had been on the pool for a couple hours and skies had been clear all night and until that point. Now tonight, with the 3 CC reading, again it was tested well after the sun had set, but this time there was no rain previous. I'm not sure what's up here. Maybe his "kit" is playing tricks on my test...? Or maybe there are other issues going on...?
At this rate, between my own pool and now my Parent's pool, I feel like I'm going to get about a month out of the DPD test ingredients from my TF-100. LOL I'm testing my own pool once a day until I get a feel for how much chlorine is used in an "average" day (and also waiting the week to re-test my CYA levels), and now I'm testing the Parent's pool a couple times a day too. hahaha Oh well, I suppose refills are pretty inexpensive.

 

[waskydiver]

So, you started the day with:

FC: 3.5
CC: 0.5
TC: 4.0

At the end of the day, with the sun on the pool for a couple of hours, you had:

FC: 1.0
CC: 3.0
TC: 4.0

So, during the day, you lost NO chlorine to UV. Yet, we are operating on the assumption of zero or near-zero CYA.

If it were me, I'd recheck my CYA levels, and clear a bucket.

Get a gallon of your pool water. 1/8 teaspoon will add 10 cc. Keep your bucket at shock level until you stop loosing chlorine.

Some may try to extrapulate the amount of chlorine required to complete the shock in the real pool, but it's really apples to oranges. More, it kinda lets you see the big picture of what your shocking process is going to look like in the real world.

 

[wes8398]

Let's not forget that yesterday morning, after testing, I also added enough chlorine to bring the level up to about 7ppm. So yes, chlorine was lost during the day.

I only have enough stuff in my TF-100 for about 2 more CYA tests, and I'm saving those for my own pool - so I'm not going to be able to test my parent's pool again. There's really no reason I can see that the test I just did 3 days ago would be inaccurate. Is there? My step-Dad's water analysis from the pool store a few days prior to me testing also said 10ppm CYA, so this could be some confirm my test results.

 

[PaulR]

It's not that uncommon to lose CYA whlie the pool is closed, so the low test result is only mildly surprising; no reason to use up precious reagent confirming your result over again.

It means your parent's trichlor regimen probably does not cause them long-term problems, and once you get this initial bout of CC cleared up the pool will probably behave just as well this year as in previous years.
--paulr

 

[wes8398]

As an update - I wasn't able to make it over there this morning to test. I stopped by at about 4pm today and tested again (18 hours after bringing FC up to about 10ppm). The day had been mostly overcast and included some heavy rain. FC was less than 1, and CC was about 3. I added enough chlorine to bring it up to about 10ppm again, and I will be returning again tomorrow morning to test again. The water's still crystal clear, so I'm hoping I'm on the right path. One thing's for sure - their pH is low. It's probably about 7, at best. Maybe 6.8. I'll work on that tomorrow with some Borax. (8 Lbs according to calculator)

Thanks PaulR. I know it's common around here to "hate" on pool stores and their sales tactics (Lord knows, I'm sick of their Crud! Thank God for TFP!); but some people (IE my parents) don't mind spending the $$ on a "kit" that will more than likely get them through the pool season with few problems. The CYA build-up that seems to be a major downfall of the tri-chlor pucks MUST be less of an issue when people are doing a proper weekly backwash (as the kit advises) and therefor replacing water on a weekly basis.
Personally, I'm not totally sold on the BBB method just yet. I'm going to stick with it and continue to learn, but right now I'm feeling like it's awfully "high maintenance" with DAILY testing and chemical balancing. I'm sure I just need to learn more about how my pool behaves and then it'll start to come with less "work".