SWG CYA and CC Help

db5304

Member
Jun 10, 2016
16
Pittsburgh
Hey all,

I thought I had everything figured out after 3 years of pool ownership starting from BBB method and converting to a SWG. However this year I'm a bit perplexed by my numbers. I have a 24k or 27k inground with vinyl that I converted to SWG last year (and am super happy). It is just a small Jandy that is probably undersized, and I was running at 80% most of the time last year with 6-8 hour a day run time on a single speed pump. I opened this year to crystal clear water and pretty good levels. I didn't have to drain/fill a ton, but my CYA levels still did not register. I bought an 8 lb bucket of stabilizer that should have raised my CYA level by 40ppm if it is in fact 24k gallons. I did not even add the whole thing, but I'm reading somewhere between 90-100 CYA. However I thought I read at some pint really high FC can throw this number off along with TA and PH. MY CC is finally down to 24 today, but has been dropping really slow. I have had the SWG in standby for 4 days now in mostly sunlight, but the water is only 60 degrees. To open, I put 2 bags of Shock that is stabilizer free that treats 16k gallons (I expected this would raise my FC to maybe 15) and ran the SWG as normal at 80% for 3 or 4 days. I started 4 days ago with a CC of almost 40, and expected it to drop much faster. I also added a thing of ALK + from the pool store as Baking Soda in larger quantities was hard to come by and expensive I believe related to Coronavirus shortages locally. I'm not sure if this messed with my numbers at all.
I do not understand how my CYA is reading so high if I added less than 8lbs of stabilizer and started at what I thought was below 30. Last year somehow I did not realize that I should be running ~80CYA for the SWG and probably why I needed to run 80%. This could be why my FC spiked so high too after I added the stabilizer since now my SWG was running too high. Can the high FC throw off my CYA reading? Could it have spiked if I was running it when I added salt as this did happen I didn't realize I was supposed to turn it off. Shouldn't a super high FC drop faster than this if starting at such a high level even with a 90+ CYA?

Numbers:
FC: 24
PH 7.4
ALK: 90
CYA ~100
Salt: 3200


Appreciate any insight. I know this is easily recoverable from, but we have some really warm days coming up, and I was hoping to get the solar cover on to try to bring the pool closer to 70. I would also love to get the cover on as this year I seem to have been invading by evil grackles that are dive pooping my pool. I've got some fake snakes on order and put some floaties in the pool to try to deter them.

Edit: Fixed, had CC and FC mixed.
 
Last edited:

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
31,023
Laughlin, NV
Your FC of 24 make the pH test invalid. It can change the colors of the TA test. But it does not change the CH or CYA test.

You had a higher CYA level than you thought when you added the CYA. Always go up in stages.

Your FC is well below SLAM level so no issue in swimming. You can cover it too, just turn off the SWCG for awhile.

Test the CYA again in a couple days. If you are getting close to 100, do the dilute test shown in the Extended Test Directions in pool school.
 
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db5304

Member
Jun 10, 2016
16
Pittsburgh
Thats what I was afraid of but thought might be the case. But happy to hear I can cover and even swim if I want to. Thanks so much for the info. I forgot about the dilute test, I will have to pick up some distilled water.
 

db5304

Member
Jun 10, 2016
16
Pittsburgh
I just tried this with tap water and its 50 where I cannot see it anymore, so if temp and FC don't matter that means I'm truly at 100 CYA. Bummer but not the end of the world especially with the SWG. Today will be a perfect day to have the solar cover on though. Thanks for the help. We have storms coming up the next few days, I typically end up having to drain some water anyways, we'll see where I'm at next week before I consider draining and refilling.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
31,023
Laughlin, NV
If you know you are getting a good storm drain off a few inches. If you just let it overflow you will normally just overflow the rain water.