CYA up?

[tcat]

My CYA was 45-50 about a month ago. Today it's closer to 65. What would cause this increase? Only using Clorox, fc not below 5 for the month. Very small amount of cc <1. Had a solar cover on for about 3 weeks. 65 is probably ok, but I'd rather have it below 50... especially if I need to shock.

My ph also keeps going up. I get it to 7.5 and in a week it will be over 8 even after adding 2-3 cups of acid. Seems odd after all being close to perfect all summer.

 

[jblizzle]

Did you let the water come up to room temperature to test it? Cold water can affect the CYA test.

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[tcat]

It's70 here, and water is 70. Bring it in the house to test?

 

[jblizzle]

Oh. Well 70 is fine. Not sure why it appears the level is going up unless the lighting is different. Or it was not fully registering for the earlier tests.

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[tcat]

"Lighting"?

 

[jblizzle]

The test is affected by the type of light in which you are doing the test.

You are supposed to do it with your back to full sunlight holding the tube st your waist.

See the extended test instructions in the testing forum.

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[tcat]

That makes sense, thanks! I thought maybe you meant how much sun hit the pool. It was overcast this morning when I checked it. Will wait for the sun to check again. Very subjective as to when the black dot disappears.

 

[UnderWaterVanya]

My CYA was 45-50 about a month ago. Today it's closer to 65. What would cause this increase? Only using Clorox, fc not below 5 for the month. Very small amount of cc <1. Had a solar cover on for about 3 weeks. 65 is probably ok, but I'd rather have it below 50... especially if I need to shock.

My ph also keeps going up. I get it to 7.5 and in a week it will be over 8 even after adding 2-3 cups of acid. Seems odd after all being close to perfect all summer.

Overcast could do it. I see a 15 ppm swing if I forget and test with the wrong lighting.

 

[lohmaraj]

well this is good information b/c I was just going to ask about a similar situation though I do know why my CYA would be up... I use trichlor. My FC level was pretty low (~2) when I realized thanks to the site here that it should be more like 4-5 so I dropped in an extra tab and let the floater sit in front of the pump inlet opening. Got my T-100 today and started testing... FC was way high ~7 and CYA was around 55... probably would not be terrible but I have an indoor pool and would rather see it much lower based on what I am reading... also just over a week ago it tested around 40 (by a pool chemical store).

Will CYA eventually float down with evaporation and replenishment if I stop using trichlor?

Also, I did the test in the evening, without following the lighting recommendations... only issue there is that we don't have full sun days in Seattle this time of the year!!!

I'll post back up tomorrow when I retest during the day.

 

[UnderWaterVanya]

Will CYA eventually float down with evaporation and replenishment if I stop using trichlor?

Also, I did the test in the evening, without following the lighting recommendations... only issue there is that we don't have full sun days in Seattle this time of the year!!!.

The CYA is there to stay until you replace some water. Evaporation just increases the concentration until you add water diluting it back to the starting point.

An option would be to get the Taylor 50ppm CYA reference solution and test it with various lighting conditions until you find one that works.

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[lohmaraj]

anyone want to qualify... no longer see the black dot? Is this completely can not see anything or its pretty much all gone and only the flash of a grayed out area remains.

I suspect that its not actually that high... I can't imagine that two 3" trichlor tabs would raise my CYA by 15? they are not even completely dissolved yet....

 

[jblizzle]

Gone. Like never there. Glance away a few times so the image leaves your eyes/memory.

There is a link to pictures in the extended directions thread.

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[UnderWaterVanya]

The first result doesn't count. Pool store tests can be very inaccurate.

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