Do I add CYA?

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C

CFPoolguy

0
Sep 12, 2017
22
Cannon Falls, MN
I'm in the middle of my very first SLAM and it's going pretty well (at least I hope it is). I think I need to give a little background before my question:

Before really starting to SLAM I did some blind vacuuming and raking to get a bunch of the crud out. Because of how fast my DE filter clogs I pumped it out the waste port then refilled the pool back to the recommended water level.

Next, I adjusted the Ph to 7.4 and added CYA to bring it to 30 (it was zero) and before bed put the filter setting on recirculate (so I wouldn't have to worry about it clogging over night) added the first shock dose of chlorine. I woke up and found a marked improvement.

I kept testing FC with my K-2006 kit every 3-4 hours and bumped it back up to shock level (I believe it's 12 for my pool and CYA-30) as needed. By about 4pm I decided it was time to start vacuuming with the filter and clear up the cloudiness. I didn't even get half way before I had to backwash and recharge the filter. Had to do it again before finishing. I finished the vacuum, let the filter run on its own for about 30 minutes and I could tell it needed another backwash- only now I have a new problem.

I had to refill the pool some before I can backwash again or the water would have gotten too low to run the pump. So here's my question(s):

Can I accurately test my CYA while in the middle of a SLAM? Will the numbers be accurate? I don't want to overshoot too far, and I'm not sure what to do with that? Also- can I get one more clarification on how to add CYA? If I add the CYA using a sock in the skimmer basket I can still backwash my filter as needed after it's dissolved, correct? I've read some people put in front of the return jet, but the pool school stuff says to put it in the skimmer.

In the meantime, I've kept the filter setting on recirculate and kept the FC up.

Thanks for the help and the clarification.

Here's my current numbers and some pics.

At 7:45 AM (before adding anything for the day).

FC- 12
CC- (between .5 and 1, I'm red-greed color blind so it's sometimes hard to tell :D)
pH- 7.4 (from test before the SLAM)
CYA- 30 (from test before the SLAM)

I don't have the original photo from before the SLAM but it was a DARK green with tadpoles and frogs living in it.

(this is yesterday morning after a night of shock level chlorinating on recirculate)

IMG_1289.jpg


This is this morning's view.
IMG_7589.jpg
 
Keep slamming at FC level of 12. You can retest CYA and I’m assuming you have lost some. Sock in front of return is better but I wouldn’t sweat it. With a lower CYA you are going to lose more FC to the sun so stay diligent in testing often for FC loss and keep to SLAM LEVELS. After you test for CYA add to get back to 30.

- - - Updated - - -

If you put it in the return some will get stuck in the filter and then you could lose more in the backwash. Sock method better but I doubt you need very much.
 
The CYA test is still accurate when FC levels are high. If you think you lost too much, go ahead and top it off.

The sock method is precisely so you can backwash if needed. The manufacturers would have you pour it down the skimmer and let it sit in the filter to dissolve. But if you need to backwash before it's dissolved, you lose it. Too bad, guess you'll need to buy more. Great for them, bad for you.

It sounds to me like you understand the process very well. Give yourself a pat on the back, if your shoulders aren't too sore from brushing.
 
Use straight pool water (no reagent) and fill the tube with it. Is it cloudy?

Are you sure of your pool volume? Did you weight the CYA powder each time you added it?

Not the end of the world. Use 60 for CYA. It rains a bit in MN, drain some water off each time a store is forecasted.

Take care.
 
mknauss said:
Use straight pool water (no reagent) and fill the tube with it. Is it cloudy?

Are you sure of your pool volume? Did you weight the CYA powder each time you added it?

Not the end of the world. Use 60 for CYA. It rains a bit in MN, drain some water off each time a store is forecasted.

Take care.
Click to expand...

With straight pool water and no reagent it is a tiny bit cloudy (as opposed to crystal clear), but then again, the pool as a whole is quite cloudy too.

I'm pretty sure of pool volume (based on when I measured last winter)- but maybe I should double check. Math was never my strongest subject. :D

no- I didn't weigh the CYA powder but measured by volume.
 
Using weight for a powder product is always more accurate. But there should not be all that much error.

CYA testing for me was problematic at start but now pretty easy. Biggest thing to know is what you add to the pool is there. No question. It does not react with anything and in most climates (especially yours in MN) it does not go away unless you drain water out of the pool that contains it.
 
mknauss said:
It does not react with anything and in most climates (especially yours in MN) it does not go away unless you drain water out of the pool that contains it.
Click to expand...

Really? So, in MN (yes it can get warm here... haha) CYA is not effected by sunlight? I always thought it was, especially since my pool gets full sun most of the day.

At any rate- One question was cleared up. I recalculated my pool volume using the calculator tool here: https://www.thepoolfactory.com/pool-volume-calculator and got 13,000 gal, not 20,000! :scratch:. Not really sure how I got 20,000 last time. (my pool is an oval about 33.5' long by 17' wide (at the middle) and an average height of 3.5 feet (all one depth, but depending on how low the water gets etc...).

Unless you or someone thinks otherwise, as you said, I'll just not worry about it and use my CYA reading of 60 knowing that it's going to go down as I backwash & then have to refill throughout this process.

Can't wait to post my pic of a sparkling clear pool! :rockon:
 
If you feel the UV on your pool is similar to S Nevada and Arizona, then plan on a 10-15 ppm drop of CYA per month from May to September.

Take care.
 

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mknauss said:
If you feel the UV on your pool is similar to S Nevada and Arizona, then plan on a 10-15 ppm drop of CYA per month from May to September.

Take care.
Click to expand...

I definitely cannot claim that the monthly UV on my pool can compare to AZ or S NV. I was just wanting to check if my understanding of how UV effects my pool here in MN was accurate or not.

Here in MN, how much average FC loss due to UV should I expect then?
 
FC loss is typically 2-4 ppm per day.

CYA loss is a much more variable item. Reports here on the forum show that it is highest in the SW desert during the summer. We do not hear of many in the northern climates having CYA loss during the summer, excluding from backwashing, splashout, or over flow due to rain.
 
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