High CYA Woes

[Mrichey912]

Just bought a house with a large 30,000+ gallon pool. Have become quite familiar with water chemistry battling a yellow algae bloom. Taylor 2006 test kit and a copious amount of chemical purchases and TLC have almost got my sparkling pool back. Problem I'm stuck with is inheriting a pool with extremely high CYA. (according to my test kit) When using the Taylor test kit I don't even reach the 100 ppm mark before losing sight of the dot. I swore off the pool stores because they had me chasing my tail when i started all this. They actually handed me a test result with high pH and low alkalinity. I followed their directions which resulted in me adding 15 pounds of baking soda which did nothing to help me at the time. Two days later my test kit finally arrives and I find out I have an alkalinity of 220. The reason I bring this up is all my pool store samples showed my CYA levels to be anywhere from 50-60 but my test kit shows 100+ ppm three tests in a row. I have added nothing containing CYA to the pool since I've owned it, just cal hypo and 12.5% liquid bleach. Could I be testing wrong somehow? It's not a difficult test to perform. The first test I ran was when I had very high alkalinity and was working to bring it down. I kind of want to take a sample into the store just to check CYA but after my last trip I don't have much faith in them.

Now that I've given my background what I'm curious about is dealing with the high CYA until natural replacement of the water brings it down. Being such a large pool I don't want to go with the forced replacement due to the already extremely high water bill I'm about to receive battling the algae bloom. Is there a safe FC level I can maintain with the high amount of CYA until it comes down? Now that I've got everything just about where I want it I really don't want to dig a deeper money pit. Any help will be greatly appreciated, this morning's test results after a OCLT below:

FC: 3.5 (4.0 last night)
CC: 0.5
pH: 7.6
Alk: 130
CH: 300

 

[mknauss]

Welcome to the forum!
100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level.
I suggest you raise your FC to 10 ppm now. Once you get a handle on your real CYA level, you will have to decide how to handle the pool water chemistry.
I suggest you read ABC's of Pool Water Chemistry.

 

[Donldson]

Sounds like the previous owner might have been quite the puck enthusiast. Just to be sure though, your CYA test is too cloudy to see the dot before it reaches the 100 line, correct? Some people misinterpret it, so I want to be sure.

Unrelated, but you mention a yellow algae bloom. Have you added anything other than chlorine to try to combat that?