CYA target on a fresh start-up?

[UberA3]

2 days ago we filled our pool with the guy helping me on start-up and we did the following.

pool is 17000 gall pebble in-ground

1 Gallon 29% muriatic acid
2 lbs of solid CYA
1 gallon 10% bleach

I tested yesterday and following the pool calculator added the following

1 gallon 10% bleach
14 oz muriatic acid

tested this morning with TFT100 and here is what I have now

FC 2ppm
CC 1
TC 3
pH 7.8
CYA is less than 20, could still see the dot at 20 but it was beginning to get cloudy.

I haven't done the TA or CH test because I wanted to focus on the chlorine and CYA first.

My question is what should my target CYA be? The pool is in direct Las Vegas sun almost the whole day. I know I have to wait for the CYA to dissolve, that's why I figured I would just add bleach until the CYA leveled out and go from there. How long should it before the CYA levels out and is the correct way to approach it. I know I don't just want to add CYA and get the level too high.

Thanks

 

[jblizzle]

That 2 lbs of stabilizer only added [s:3vxth8ii]7.8[/s:3vxth8ii]14ppm of CYA ... so of course that is not measurable. You should get that up to at least 30ppm by adding another [s:3vxth8ii]6[/s:3vxth8ii]2+ lbs ... or even a little higher given the amount of sun you say you get.

Once the CYA is dissolved, assume it is active and adjust your minimum FC accordingly ... then test in a week to verify the CYA level and adjust again as needed.

EDIT: After seeing Richard's post, realized I used 2lbs of trichlor and not stabilizer

 

[Richard320]

For Las Vegas heat and sun, I'd aim for 50 CYA. The 2 lbs you added should have only raised your pool to 14, according to Effects of Adding Chemicals in http://www.poolcalculator.com/ It also says a total of 7 lbs is needed, so you have 5 more pounds to add. I hope you've done enough reading here to have heard of the sock method. Since you're in control of what goes into your water, you can safely use the calculated CYA levels until it's all dissolved. Test it in a week. Unless you opt for liquid CYA, which will only need an hour or so to mix well.
In the meantime, with 14 CYA, your FC target is 1 to 4. The CC is most likely chloramines from the fill water. But if they don't dissipate soon, you might have your very first algae bloom starting already, so do monitor that.

How have you been calculating your acid doses if you aren't measuring TA?

 

[UberA3]

I guess I was using the pre-set parameters for the PH test. I read about the sock test, we just sucked it into the filter via the skimmer. I added the rest of the box so that puts me at 5lbs now, should be 35 CYA when dissolved. Will add one more pound and recheck once it dissolves.

thanks

edit: bonehead math error

 

[jblizzle]

Something is not right. For 17k pool, you would need 7 pounds total to get from 0ppm to 50ppm of CYA.

Check that you have the correct volume set in the calculator.

 

[UberA3]

Something is not right. For 17k pool, you would need 7 pounds total to get from 0ppm to 50ppm of CYA.

Check that you have the correct volume set in the calculator.

You're correct! I have been working with measurements and incorrectly I have been using 12 oz in a pound instead of the 16 oz. What a bonehead move!!

 

[jblizzle]

Well, there you have it ... a simple fix between the ears

 

[UberA3]

Ok so after adding a total of 6 lbs of CYA it is now at 55. My pool must be a less than 17k the blueprint shows. By this number my target FC should be 6.5. My question is when should I aim for this number? The night, the morning, or mid day for an average of 6.5? If I have it at 6.5 in the morning it is usually something like 3 in the night. Also I am adding about 1/2-3/4 gallon of 10% bleach a day. Does this seem in line for the numbers?

Thanks

 

[Richard320]

If you test at the same time every day, and it's never below 3, you're doing just fine. 3 is the minimum for 55 CYA. Personally, I'd pad it an extra 1 ppm for insurance.

Your chlorine consumption works out to about 3 ppm.day, which is probably normal for the heat you have.