New pool owner struggling with test levels and getting it right

[GenAric]

Background:
My wife and I purchased our home in South Texas (San Antonio area) back in October of last year and we've officially been struggling with keeping my pool levels balanced for just as long. We've had some serious issues with the back yard which included us having to gut the existing patio and replace it with concrete. Our pool was out of commission almost the entire first half of the year because of that. I have been able to keep it from turning green (and even recovered from an algae bloom, thank god!)... But now that the patio work is done, I need your help!

Pool facts:

• Style: Latham Viking Caribbean fiberglass pool
• Size: 17,000 gallons
• Geographic location: South Texas (San Antonio)
• Sanitizer used: bleach/chlorine
• Pump: Jacuzzi JVS270S (2.7 hp variable speed pump)
• Filter: Jacuzzi JSF26 26" Sand Filter (filled with glass medium)
• Chlorinator: In-line erosion
• Features: two cascades

Historic issues:

• My pool will not keep its chlorine levels at all, even after SLAMing it.
• My CYA levels are always high... In fact, the levels weren't even measurable with the TF-100 test kit that I have; I've already had a pool company come out and drain about 1/5 of the pool to replenish it with fresh water, CYA still very high.
• I live in the area of San Antonio supplied by the Edwards Aquifer... meaning TONS of limescale on the pool surface.

Current Test levels (measured on 11 October at about 9 am):

• pH: 7.6
• FC: 4ppm
• CC: 1ppm
• CH: 575ppm
• TA: 180
• CYA: 90ppm

The pool calculator from TFP says that my numbers should be this:

• pH: 7.2~8.0
• FC: 8 ~ 13ppm
• CC: (not a recommendation?)
• CH: 250~650
• TA: 50~90
• CYA: 30~60

Please help me get my FC, TA, and CYA numbers in check!

 

[Mdragger88]

Welcome to tfp
I’ll try to address your questions/issues
*cya-
For the cya the only way to lower it is to exchange water. You can do this yourself with a submersible pump.
If you are concerned with your water table lifting your pool you can do a no drain water exchange. See Section 3.5

Draining - Further Reading

www.troublefreepool.com

It’s a 1 to 1 ratio - if you want a 50% reduction in cya (which is the case for your pool) then you need to replace 50% of the water. This will also lower your ch level which would be a good idea
If you are currently using stabilized (trichlor) chlorine tablets in the erosion feeder take them out. That is what caused the high cya in the 1st place.
Save the tabs/feeder for vacation- not daily chlorination.
*Fc-
You need to use liquid chlorine daily & follow the FC/CYA Levels. Pour it slowly in front of a return- u can brush the area as well to distribute it.
With a cya of 90 your target fc level is 12 & it should never be allowed to drop below 8 lest nasties will grow.
If you have regularly been below minimum for your cya you may already have things growing that are consuming your fc- to rule this out you need to do an Overnight Chlorine Loss Test.
If you do not pass or you have visible algae you will need to do the SLAM Process. Its not advised to try to slam with such a high cya.
Such a high cya level which requires a maintenance fc level above 10ppm also makes it hard to regularly check your ph. The ph test gets skewed at fc levels above 10ppm.
* cc’s - combined chlorine = chlorine that’s fighting something organic, this is an indicator that you have something brewing & need to SLAM
Ideally there should be .5 or less cc’s in an outdoor pool.
It could also be a testing error - if you let the sample sit too long it will become pink again. When you do the overnight chlorine loss test be sure to not let the sample sit after doing the r-0871 drops.
*ta -
Your ta will come down overtime as you lower ph when it rises to 8.0
- adjusting ta is last on the list of priorities especially if a large water exchange is in your future.

If you have any more questions just ask.

 

[HermanTX]

+1 on @Mdragger88
As suggested above, get your FC up to the 10-12ppm range but remember that your daily additions of liquid chlorine should be to replace your daily loss of FC due to UV and swimmer load. I would test daily at the same time each day to monitor what your daily FC loss is. Right now I am pouring about 48 ozs of LC daily to maintain my loss just to give you some perspective. I add mine in 2 doses - some in morning and then balance in late afternoon. I run my VS pump 20-22 hrs per day so I am not tied to a specific time to add each LC dose. My goal is to keep a steady level of FC at all times rather than making a big dose and let it dwindle down throughout the day and night.

Hopefully your CC of 1ppm is a testing error as that is an indicator of potential algae trying to take hold.

Also, don't use any pucks in your inline chlorinator as that is adding to your CYA. Focus on using LC for to raise your FC and also to maintain it there.

It concerns me when you say "My pool will not keep its chlorine levels at all, even after SLAMing it". this tells me you had an issue and maybe that is still lingering. With a CYA of 90ppm, that is protecting your chlorine however the FC is not high enough to have it properly sanitized. Also, you really do not want to SLAM with CYA of 90 as that would require a SLAM level of 36ppm FC.