Newbi to Forum with New-ish Pool Issue/Questions

[tucsontico]

Excuse the length of this post but I thought it best to include as much info as possible.

My pool was finished Apr 12, 2013. (My signature block contains the pertinent data about the install.) I followed my installer's suggestion and bought a Taylor K-2006 test kit. Monitoring my pool chemistry during the first season allowed me to get a "feel" for the way it will react in the full sun, hot, southern AZ summers.

We have a light swimmer load (my wife and I swim 2-3 times per week). Last season I noticed the FC levels always were a bit "high" (6-8 ppm) and I was using a lot of the Frog BacPacs (Trichlor)–about 1 every 2 weeks versus what the manufacturer stated "normal" use is–about 1 every 3-4 weeks. Additionally, my pH was always rising towards 8.0 each weekly test. I could never get it to stay down into the 7.4-7.8 range for more than a few days. The TA averaged 100 ppm all season. The CH hovered around 300 ppm all season also (Pretty common for the hard water here in Tucson). I tested the CYA value 1 week after the initial fill and it was high: 90-100. However, the water appeared clear and thought nothing of the CYA number.

Towards the end of last season (Oct) I had a small green algae bloom. I was able to treat it via a dichlor shock treatment with aggressive brushing and filter cleaning. But as temps cooled off I was still using lots of Frog BacPacs and the FC kept going higher (8-10 ppm) even after setting the Frog Inline Chlorinator to its minimum setting. After research and contacting King Technologies, I discovered the pool builder installed the Frog system on the wrong side of the return. They had placed it on the in-floor cleaner side of the return where it was getting too much pressure. This was causing the BacPac to be used up twice as fast as normal and put too much chlorine in the pool. This plumbing error was repaired in Oct 2013. Following the repair, I got the FC stabilized to 2-4 ppm but the pH continued to stay high (7.9-8.1) and resisted weekly muriatic acid treatments.

As the weather has begun to warm, I am trying to get the pool back in great shape. I tested the water with my K-2006 kit with these results:

FC-0
pH-8.0
TA-125
CH-300
CYA-100+
Water Temp- 70ºF

Other than the FC and CYA, I know the other numbers are close to desired ranges. Due to the calibration marks on the Taylor CYA turbidity test, I couldn't accurately assess how high the CYA is. I took samples to two pool stores to see if they could give me a better idea. They estimated my CYA value at 120-150.

My questions are:

1) Is there an accurate CYA test for values above 100? I need to know how much water to remove/replace in my pool.

2) Could the introduction of "excess" trichlor from the Frog PacPacs caused the high CYA value in one season?

3) Could the ozone injector cause pH rise due to "aeration effects"?

4) Can the in-floor cleaner cause pH rise due to "aeration effects"?

BTW, this forum is a wealth of knowledge and should be the first stop for ANY pool owner! Any help with my issues/questions will be greatly appreciated.

 

[JasonLion]

Welcome to TFP!

1) No. You can get a rough value by mixing equal parts of pool water and tap water, doing the CYA test on that, and multiplying the result by two. What you are really going to need to do is replace about half of the water and then measure the CYA level again.
2) Partly, though the dichlor used for "shocking" certainly provided a good part of the CYA.
3) Ozone provides a little aeration, though not usually enough to be important.
4) Unlikely, only if there is air in the system, which there should not be.

Most of your PH increase is coming from having fresh plaster, which raises the PH for up to a year. Some of it is coming from the TA being fairly high.

You should strive to never let the PH get up to 8.0.

Remember, your target FC level depends on your CYA level, so most of last year your FC level was way too low.

 

[Smykowski]

Welcome to the forum...

Jason beat me to it, but I'm going to add a change to number 2. Yes, that's where your CYA came from. The Bac Pacs are just an expensive TriChlor delivery system. The bigger problem is that the mineral packs are full of junk you don't want in your pool. I've got copper stains on my liner above the water line because of a previous owner's exclusive use of the pool frog. He told me after the closing how great they are, and I can't tell you how happy I am that I stopped using them when I did. I ripped the dispenser out of my plumbing last year before the season started.

If you decide to maintain your pool via the TFPC method, you're going to have to do a major drain to get the CYA down.

 

[tucsontico]

Thanks to both JasonLion & Smykowski for the quick responses. Never thought of the dilution trick with tap water for CYA test–excellent idea!

Forgot to ask if the high CYA value will prevent lowering the pH due to CYA buffering.

Never had any trouble with stains using the pool frog system. (This is my second pool with that system.) Personally, I like the ease of the chlorine delivery. The added minerals may have prevented a larger algae problem since my FC was too low for the CYA value last season. However, I now know that the trichlor is adding to the CYA. I suspect the pool builders added too much CYA during the initial fill which was exacerbated by the incorrect install of the pool frog.

Anyway, I greatly appreciate the information on your site and your help with my issue. I plan on draining about 60% of my pool water, re-testing and using the TFPC process to get my pool water perfect. Thanks again!

 

[zea3]

Hi, welcome to TFP! The CYA does not affect the pH. Any system that injects air into the water will cause the pH to rise, plus pH will rise while your plaster is curing, probably for at least a year. You will need to check the pH every couple of days and correct it until it has stabilized.

 

[tucsontico]

Hi, welcome to TFP! The CYA does not affect the pH. Any system that injects air into the water will cause the pH to rise, plus pH will rise while your plaster is curing, probably for at least a year. You will need to check the pH every couple of days and correct it until it has stabilized.

I know adding CYA will not increase/decrease pH. However, I was under the impression that CYA buffers the pH from falling. Is that not correct? Also, I read on your site that borates buffer the pH from increasing.

I tested my fill (tap) water with these results:

FC- 0
pH- 7.4
TA-120
CH-250
CYA- 0

Due to the high CYA noted earlier in this thread, I drained about 70% of my pool today and am currently refilling it. My plan is to retest my pool water and start the SLAM process tomorrow. I've ordered a 55 lb bucket of boric acid from DudaDeisel.com to add borate to my pool after the rest of the chemistry is stabilized per TFPC recommendations.

 

[JasonLion]

CYA does provide a small amount of PH buffering, though not enough to make any material difference in most situations.

 

[tucsontico]

OK. Thanks for that info! Can I assume that borate provides a stronger buffer to pH rise?

 

[Smykowski]

Yes.

 

[Casey]

If you want ease of use, remove the frog and install a Salt Water Generator SWG.

 

[tucsontico]

Thanks again! I've owned 2 pools and thought I knew enough to operate the a pool with minimum hassle. However, I've learned so much from this forum now I feel confident and competent in my pool chemistry.

I'm hoping my recent empty/refill will allow me to get the chemistry stable and not fight the pH and FC so much. But, I've been considering the SWG. I believe I read that there is a much increased acid demand with an SWG–is that correct? For a pool of my size (16' x 40' and about 20000 gal) and location (full sun, all day), the daily chlorine demand could be fairly high. Would this chlorine demand require daily and/or weekly muriatic acid dosing?

Thanks for such an informative website!