Drain or not to drain…?

[Laziebun]

Long story short my numbers are below via K2006

FC 21.5 (good news no drop on OCLT)
CYA 80
TA 250
PH 7.4

Thinking ahead, I use 3inch chlorine tablets and have two 40lbs cases of them. What I have read are the tablets let’s out CYA as well. With my current CYA at 80 I’m assuming once my FC drops to the appropriate numbers I’ll introduce the 3” tabs which technically will raise my CYA.

Question:
1. Should I not use the tabs?
2. Drain the pool now which will also help drop the chlorine level and CYA

Concerns of CYA getting out of control.

 

[Texas Splash]

To your questions:
1 - Correct. Leave them alone for quite awhile until the CYA falls much lower (30-40). Then you can use them occasionally or if on vacation.
2 - Up to you. It will lower the CYA, or you can increase your FC based on the FC/CYA Levels until the CYA falls.

 

[kimkats]

Your CYA is a bit high already. As such the tablets are a no go at this time. What you need to use is liquid chlorine. You can find it at your local pool store (but this the only thing you should buy from them), Walmart (has it in a white jug that says pool shock but it really just chlorine), Lowes, Home Depot (make sure to check the date codes from these two places).

Look at this chart:
FC/CYA Levels Note how the higher your CYA is the higher you need your FC. It is a viscous cycle with using tablets.

Now if you water is cheap then you sure can dump some and replace to lower your CYA but remember each tablet will add more CYA. You can use PoolMath to see how much CYA each tablet adds.

What I would encourage you to look at is a SWG as seen here:

SWG How It Works - Further Reading

www.troublefreepool.com

Now the up front cost is a bit BUT the down the road cost it evens out. What the biggest payoff is in a LOT less work for YOU as the SWG does all of the work for you! Just something to think about.

 

[Mdragger88]

If u just discontinue tabs & use liquid chlorine you will still need to maintain a target fc level of 9-11
Always follow the FC/CYA Levels
SLAM Process fc level for that cya can be tedious to maintain if a problem arises. The ph test is also invalid at fc levels over 10ppm so u would need to check/adjust that when the fc dips.
Replacing 50% of your water would definitely put u in a better place @ around 40ppm cya.
Each dissolved 8oz puck has this effect on your water

Even at 40ppm cya - using pucks for daily chlorination will put u back in this situation quickly.
Its best to reserve them for occasional use to bump cya a dab & for vacations.

How to Chlorinate Your Pool

Before chlorinating your pool, you should know these simple tips. Learn the best way to add chlorine to your pool.

www.google.com

 

[Laziebun]

To your questions:
1 - Correct. Leave them alone for quite awhile until the CYA falls much lower (30-40). Then you can use them occasionally or if on vacation.
2 - Up to you. It will lower the CYA, or you can increase your FC based on the FC/CYA Levels until the CYA falls.

My understanding is CYA will not drop on its own and the only way to lower it is to drain and replace water.

 

[Laziebun]

Look at this chart:
FC/CYA Levels Note how the higher your CYA is the higher you need your FC. It is a viscous cycle with using tablets.

Does this mean I need to increase my FC to 31ppm since my current CYA is 80ppm?

 

[Newdude]

My understanding is CYA will not drop on its own and the only way to lower it is to drain and replace water.

If you want it done relatively soon, then you are correct. It will burn off about 3-5 ppm a month by itself, probably on the low side of that for you with much less UV in Chicago than the hot climates.

Rain and filling after evaporation will dilute it also, but only by the appropriate %s. Folks tend to grossly overestimate this one. 'We gad a big storm with lots of rain !!! I'm OK now !!! But it's only 4 inches out of the 30 (?) Needed to lower you by half.

Does this mean I need to increase my FC to 31ppm since my current CYA is 80ppm?

Only for SLAMing. Regular operation is 9-11 FC per the chart, and plenty to perform an OCLT there. But it brings up another question. Was your FC at 21 for a reason. ?

 

[Texas Splash]

My understanding is CYA will not drop on its own and the only way to lower it is to drain and replace water.

CYA degrades a bit each month by about 5 ppm give or take a few. So over the course of your season it should fall. Your signature is blank, but if you have a sand filter and backwash that will accelerate CYA drop.

Does this mean I need to increase my FC to 31ppm since my current CYA is 80ppm?

No. Only 31 if performing a SLAM. Otherwise, for regular season maintenance per the FC/CYA Levels, the ideal range would be 9-11, never lower than 6.

 

[Laziebun]

.
Only for SLAMing. Regular operation is 9-11 FC per the chart, and plenty to perform an OCLT there. But it brings up another question. Was your FC at 21 for a reason. ?

I was frustrated with the cloudy water so I dump a ton of liquid chlorine. Two days ago it was at 35ppm. So it’s drop quite a bit from UV, vacuuming and backwashing.

 

[Newdude]

was frustrated with the cloudy water so I dump a ton of liquid chlorine

From now on you use precision, not dump and pray. We will help at every step if you need. Have a read.
SLAM Process

 

[Laziebun]

I have a vinyl pool and scared to drain to much at one time. Is there a recommendation on how much I can drain without messing anything up? If I have to drain and refill, I don’t have any issues doing that at all. Or should I just let it be, and keep my FC according to the CYA “liquid chlorine” table? And hold off from using the tablets and start using liquid chlorine to maintain my FC.

 

[Laziebun]

From now on you use precision, not dump and pray. We will help at every step if you need. Have a read.
SLAM Process

Learning the hard way. Lol. That’s what I get for making an emotional decision

 

[Newdude]

Is there a recommendation on how much I can drain without messing anything up?

The reccomendation is to leave at least a foot in the shallow end to ensure the liner stays in place. Start paying close attention to it at 18 inches. While it wouldn't be half of you water, it would be a great head start leaving you with a more manageable CYA of 40-50.

Subsequent drains remove new water with the old and become less efficient with each drain, but still get to the same spot eventually. Keep that in mind if you decide to drain several times.

Or you can keep your FC per the chart at your higher CYA and wait it out, expecting it to use more chlorine to do so for this season. The rest will seemingly fix itself over the off season when you walk away from it for 6 months.

 

[Bperry]

I’m kinda thinking that if you can get the CYA down just enough to be able to regularly keep the FC under 10ppm and that will let you measure the pH regularly to keep things under control. As the season goes on, with use, sun, filter cleanings maybe the CYA drops a bit more which just makes things easier as long as you don’t use any more pucks. Nothing to lose that way except a bit of money on extra chlorine. If it doesn’t drop enough by end of summer, closing it and all that may get you close enough over the winter.

 

[Laziebun]

I’m kinda thinking that if you can get the CYA down just enough to be able to regularly keep the FC under 10ppm and that will let you measure the pH regularly to keep things under control. As the season goes on, with use, sun, filter cleanings maybe the CYA drops a bit more which just makes things easier as long as you don’t use any more pucks. Nothing to lose that way except a bit of money on extra chlorine. If it doesn’t drop enough by end of summer, closing it and all that may get you close enough over the winter.

According to the CYA chart I need to be at 80ppm for CYA to maintain/target FC at 9-11ppm, with a minimum of FC @ 5ppm. So technically I’m there now right?

 

[Newdude]

So technically I’m there now right?

Yup.

 

[Bperry]

According to the CYA chart I need to be at 80ppm for CYA to maintain/target FC at 9-11ppm, with a minimum of FC @ 5ppm. So technically I’m there now right?

Yes. Your kinda on the fence so to speak. The pH test is only valid below 10ppm FC. So depending on how and when you test and add stuff is might be tricky. Maybe testing in the evening would be best as the sun can burn off some chlorine during the day and get it below 10ppm, then you can dose it back up overnight. If your CYA was a little lower, youde have more flexibility.

 

[Mdragger88]

According to the CYA chart I need to be at 80ppm for CYA to maintain/target FC at 9-11ppm, with a minimum of FC @ 5ppm. So technically I’m there now right?

Yes - u need to maintain 9-11 ppm fc for your current cya level lest nasties will grow
if u lower the cya level you can lower your daily & SLAM targets according to the FC/CYA Levels. Minimum is not a goal - it’s hot lava…
If u are having cloudy water you need to do an Overnight Chlorine Loss Test to rule out organics.
*If u pass you continue to maintain target fc levels for your cya.
*If you fail you will need to do the SLAM Process to eradicate algae.
This can be harder/ more expensive to do at such an elevated cya level. A water exchange would definitely help either way.
It’s directly proportional- to have 50% less cya you would need to exchange 50% of your water for fresh water.

Draining - Further Reading

www.google.com

 

[Laziebun]

We’re about to get some rain… thought on letting rain water in or should I cover the pool?

 

[duraleigh]

Let it rain.....it will only help you