Chlorine and CYA

Aug 11, 2014
3
Mesa, AZ
MY CYA is between 90-100, through being pool stored and told to add to much stabilizer as well as having been using TriChlor pucks. Pool was just resurfaced in May so fresh fill at that time. Issues I am seeing are going from FC of 8.5 to 5 daily, which means I am adding 1 gallon of 10% Liquid Chlorine nightly ( may not need exactly 1 gallon but I am working to get closer to a FC of 10). It would seem that with this high of a CYA I wouldn't lose this much in a days time but that's what the FAS-DPD test is telling me. I know I need to get the CYA down to 50 but having just filled the pool ( 24,000 gallons) a couple of months ago I am trying to get to the fall/winter months without draining what appears to be will need to be 40 - 50% of the water. The other issue I am having is that we are seeing significant calcium build up on our grout lines. Our Calcium is about 350, not bad considering it's 250 - 300 out of the faucet here in Mesa, AZ. I am just surprised to see what appears to be a significant calcium issue in this short of a time period. I might add the pool looks great, crystal clear water, PH is being maintained at 7.3 - 7.8 with Muriatic Acid, although TA a week ago was running 140. I have been working to reduce this through adding acid and aerating. In summation I guess my main concerns are: 1) Is this amount of FC loss normal. 2) is there something I may be missing which is leading to my Calcium issues?
 
:wave: Welcome to TFP!!!

1) It is normal to have to add 2-4ppm of FC everyday. So you are a little high. My guess would be that, you are letting the FC get too low and there may actually be something starting to grow in the water. According to the FC/CYA Chart, you should never let the FC get below 7ppm.

2) Are you just talking about the ring around the tile? That is not really calcium scaling per se, but the deposits left due to the high levels of evaporation that we have.
 
Thank you for the welcome and your response.

I have passed the OCLT so I do not believe I have anything growing. I have read volumes on the site and believe I have a good understanding of the TFP methods and math. I had not realized the need to have a much higher FC when realizing high CYA readings which is another item that has me a bit perplexed as prior to reviewing the CYA to FC chart I was keeping the FC around 3-5 and was not seeing any issues. Water was clear, no algae growths, etc. Once I read the chart and associated postings, it made sense so I thought, "I must have just been lucky" and decided to go to bleach and or liquid chlorine (10% liquid has been running on sale at the local pool store for $4.88/2 gallons).

Being that I am in Mesa, AZ one thing of note is using just ambient temperatures for a heat source our pool water has been in the 92-93 range for over a month.

The calcium deposits I am talking about is not a scum ring but actual hard deposits. I have scrubbed them with a nylon brush which has had little to no effect. I scraped the bigger deposits with a plastic scraper and the larger pieces came off but still leaves a white residue behind.

I have owned the pool for 21 years and have always handled the chemicals and maintenance myself, although not using the TFP methods or levels. I am fairly adept at using a test kit and performing most maintenance items, adjusting levels etc.

Again, I was surprised to not be having issues when running FC levels of 3-5 with CYA of 100. I hadn't tested the CYA for a month or so prior to receiving my Taylor K-2006 but the stabilizer I added was right after filling the pool in May. Also had been using TriChlor since that time so not certain when it reached these levels but have to think it has been at least above 80 since a week after initial fill and climbing with the use of TriChlor ever since.
 
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.