final numbers after drain to reduce CYA

[miwitte]

Finally got the CYA under control.

Final numbers- CYA 55, FC 6, CC 0, PH 7.4, TA 60 Calcium 60. Water temp 60. Number look good but the CSI index seems high at -1.1. Do I need to raise my TA and CL before my final SLAM or can I leave for winter? Its a vinyl with a heater so not sure about the heater and the copper in it.

Next is a slam. I have not done one, so pool math says for my CYA use 24 for shock FC. Maintain until my OCLT drop is less than 1 PPM and CC is less than .5(mine is zero now). Pool is crystal clear no signs of any algae which I had 3 weeks ago(I kept chlorine around 30 2 weeks ago but CYA was very high maybe 180+ that seemed to get rid of it).

Thanks again to the forum I learned a lot since sept when I started BBB.

 

[Texas Splash]

CH is typically not an issue for vinyl pools as noted on the recommended levels chart of 0-350ppm, so there's no need to adjust. But if you did chose to adjust it, Poolmath shows to add 592 oz of calcium chloride which would get it back to a reasonable -0.48. In addition, adding 94 oz of baking soda will raise TA to 80 and further enhance your CSI to about -0.32. Then after the SLAM, you could let your pH rise back up to about 7.6-7.7 which will take it closer to neutral. But again, all of that isn't really necessary for your pool type.

As for the SLAM, yes, an FC of 24 is your goal. Just follow the directions on the SLAM page and you'll be fine. Maintain is the key.

 

[Pflugerpool]

Why are you doing a SLAM if your combined chlorine is 0 and your pool is crystal clear? What's your current OCLT result?

 

[duraleigh]

Why are you doing a SLAM if your combined chlorine is 0 and your pool is crystal clear?

Yep. There seems no need.

 

[borjis]

CH is typically not an issue for vinyl pools as noted on the recommended levels chart of 0-350ppm, so there's no need to adjust.

I used to think that too, but he's got that Heater (same one i have) and the warranty is no good unless the CH is at least 200.

 

[miwitte]

Honestly never did a shock before the winter so really not sure what to do I just figured that's what everyone did. Also I don't cover and close just run pump all the time when its freezing. Been doing that 13 years never had a issue. If I don't need to slam I won't then. Just looking for advise using this method. Figure I could bring cl up.

 

[PAGirl]

You could run an overnight chlorine loss test, just to reassure yourself a SLAM isn't needed.

 

[Texas Splash]

Miwitte, that makes more sense now. You're not really SLAMming in the technical sense, just thinking of taking your water to SLAM/Shock level in preparation for closing. However if you don't really close the pool like others up north (disconnect pump, cover, etc), and you have no indication of algae, then you really don't need to do that either. Just keep doing what you're doing. The colder water will slow-down FC consumption and make pool care much easier on you. As for the CH, check your warranty paperwork for your model. Many folks have no issue with low CH, but your spec may dictate otherwise. If so, Poomath will help as I noted above.

 

[miwitte]

That's what I thought, so SLAM is really only if you actually close it. I have a weird shaped pool so I would need a expensive custom cover. The guy that built the pool told me to just to the pump in the winter and if its below freezing then keep it running all day and night. It really only gets below freezing maybe 10-15 total nights then its up to 45-50 in the day. I am so glad I got the CYA down now I can run my chlorine much lower I am pretty sure its not good for the liner to be running at 19 FC like it needs to be with a CYA of 200. Ill try and balance my CSI index a little better but things look good.

Thank god that guy fixed that leak for me so easy.

 

[borjis]

I am pretty sure its not good for the liner to be running at 19 FC like it needs to be with a CYA of 200.

With your pool over stabilized that high it's counter acting the chlorine's effectiveness, so it's not likely it was any harsher on the liner. at a CYA level of 50 you bet it would be harsh. and on your swimwear and hair too.

Though it is a good feeling to have the CYA at a proper level and spend less on chlorine.

 

[pabeader]

borjis has got it mostly right. Just to put a fine point on it, I'm adding this thought. It isn't FC by itself, but the relationship between FC and CYA, that matters to liners and people and cloths. A FC of 20 with a CYA of 100, is the same, as far as actual 'working' chlorine, as a FC of 10 and a CYA of 50.
The CYA acts as a buffer to the chlorine so that only a fraction is actually active. As that fraction gets used up, the CYA bound chlorine gets released, which keeps the percentage constant.

 

[miwitte]

Ok so final #s today
FC 7.5
CC 0.0
PH 7.6
ALKY 80
CYA 50
CL 210
CSI -.3
OTCL showed no loss. Pool sparkles and shimmers haven't seen it look this good in a long time. Looks like I am set just need to keep chlorine up over winter. Going to figure out some type of dosing pump setup over winter. Also looks like gallons are 21,000 played with pool math to figure out how much I added to make changes and 21000 seems pretty close.