To Drain, or Not to Drain?

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T

tmack3

0
May 19, 2017
5
Johnson City, tx
So I've been reading a lot of the threads concerning high CYA and CH. Here are today's numbers. I recently purchased the TF 100 test kit after having my doubts about the pool store numbers.

FC 2
Ph 7.6
CC 0
CH 800
TA 90
CYA 100
CSI 0.04

This is a relatively new pool, in ground, plaster, 25k gal. Filled in April of 2017. The water is very clear, and haven't had any trouble for far, but want to avoid any potential problems. Used the auto-chlorinator with the 3 inch pucks last season, unaware that they were full of stabilizers. I'm blaming them for the high CYA. So I've now switched to liquid bleach. We are on well water, which when I tested the auto pool fill water it came out to 325 ppm. I do have a hose bib on the house that has softened water. It checks out at 225 ppm

I know the FC is a little low, but I've been letting the pucks dissolve in the tube. They're almost gone now. Been adding liquid since.

So here's the question: Would you drain and replace water? If so, how much? I think the CSI number is on target, so maybe the high CH won't be an issue. But since both CH and CYA are high, just do it and get it over with? Looking for some advice.

tmack3
 
Hello tmack and welcome to TFP. You have found your home for all pool maintenance actions.

You are thinking correctly IMHO. Plug your numbers into PoolMath (top of page) or PoolMath App and it will tell you how much water you need to replace. You should focus and target CYA of 30-50ppm for non SWG pool. Living in Texas (might be Tennessee?). I would target 50 or a bit higher in the summer months. Your FC is too low for your current CYA of 100. To the local store to buy Bleach or Pool Chlorine you go.

Pool fill going forward would be best with the softened water. Several members run higher CH levels living in the desert areas and are successful with higher than 350CH.

BTW: You say 25K gal. in your question but your signature says 28K. Those will make a slight difference in PoolMath calculations.
 
Welcome to Trouble Free Pools, glad you found the forum when you did and that you've already purchased the best test kit you can get. :)

When you test CYA, if you get a result of 100 or close to 100, do the diluted test as described in the Extended Test Directions in my signature. If the initial test comes back as 100ppm CYA, you likely have 150ppm or more, especially if chlorinating with pucks. You're gonna have to do a partial drain no matter what, but doing the diluted test and knowing what your results really are will give you a better sense of how much water to drain.

Also, if you're new to testing your own water, read over all the sections of the Extended Test Directions to get a good idea of how to do each test so you'll feel confident in your results.
 
I agree very much with the advice above. You could take it down to 60 ppm CYA and be OK for another couple years in terms of calcium hardness. Be careful with draining. Does your well water have iron in it?
 
needsajet said:
I agree very much with the advice above. You could take it down to 60 ppm CYA and be OK for another couple years in terms of calcium hardness. Be careful with draining. Does your well water have iron in it?
Click to expand...

Thanks, y'all, for your responses. Yes, Texas, not Tennessee. Retired here from Minnesota a few years ago.

No, no iron in the well water. At least not according to the pool store test. But then again, I don't have a lot of faith in those.

I'll try the extended CYA test to see what it reads.

I can't say I'm surprised by the advice to replace water. That was my gut feeling all along. It's nice to have another's opinion who has much more experience than I do.

BTW, hubby is now contemplating a SWG. Thoughts on that, or is that another thread? :)

25K gal is hubby's number based on gpm when filling. 28K gal is pool math number. But the pool does have rounded bottom, so maybe that takes away some gallons?
 
CH and CYA are a bit annoying in that once they enter your pool, the only way you can feasibly get them out is by replacing water. Yes CYA can technically be replaced without draining by introducing a bacteria to the pool that eats CYA and produces ammonia, but I'm assuming you immediately see the issue and safety concern with adding large amounts of bacteria to your pool. Pool stores seem to think that's a good idea for some stupid reason.

Anyways, about a SWG, I just recently installed a Circupool RJ45 SWG and love it so far. With any SWG, if you plan to go on a vacation for a few weeks, you don't need to worry about your pool getting low on FC while you're gone. :D
 
Thanks for the tip on the Extended Test Kit Directions. Although I have to say that the CYA test is kicking my behind. Yikes! I've had results from 70-100! I tried diluting the pool water as per the extended direction, and got 70 once and 80 a second time. Does that make sense? Although it's a cloudy day here. Does that make a difference? How does the pool store test CYA anyway? They don't stand outside with their backs to the sun. Haha.

Thanks, too, for the tip on reading them all. I redid my CH test with those instructions and came up with 625. Still high, but believable. I was having the issue with the water turning purple, so I redid the test per their instruction and came up with the new number.

Pool Store: CH 280 12/4/17
CH 470 3/7/18

FC now up to 3. Added 8 cups of 10% liquid bleach to get from 2-3. Added another 8 C today.

I'm going to keep practicing on that CYA test til I get 2 of the same answers. Sheesh!

Pool math says to replace 50%. We'll get started on figuring out how to do that.

And thanks for the opinion on the SWG!
 
With CYA a bright sunny day is need to make sure your results are accurate. I tested my water at the pool store out of curiosity and they said my CYA is 50ppm when it's really 70ppm. Also said my FC is 4, whereas it's really 10.

Not sure if you're aware but with CYA test, you can pour the solution back into the red tipped bottle and start over without using more reagent. Just keep pouring into narrow vial to test and then back into re tip bottle until you're confident in your results. Also, don't stare at the narrow vial, just look down and glance.
 
Hi again, just a nudge to take your FC up to 10 ppm. It sounds like you might be able to get along without draining, but do get FC up to 10 and keep it there. Do a Overnight Chlorine Loss Test test first chance you get, the rest is probably manageable as is.

Does this look like your current numbers?

FC 3.0
CC x.x
pH 7.6
TA 90
CH 625
CYA 70-100 (call it 80)

Keeping FC somewhere above 8 or 10 and anywhere up to 15 or 20 is completely unnoticeable in your situation, and nice for swimming. Maybe giving yourself a FC range will make the CYA test less troubling.

I'll bet around one in a thousand SWG owners go back to liquid.
 
tmack3 said:
Thanks for the tip on the Extended Test Kit Directions. Although I have to say that the CYA test is kicking my behind. Yikes! I've had results from 70-100! I tried diluting the pool water as per the extended direction, and got 70 once and 80 a second time. Does that make sense? Although it's a cloudy day here. Does that make a difference? How does the pool store test CYA anyway? They don't stand outside with their backs to the sun. Haha.
Click to expand...

With the diluted test, you're supposed to double whatever you read on the side of the narrow vial. So when you say you got 70-80 after diluting, was 70-80 what was on the side of the vial, or did you read 30-40 and double it to 70-80? Basically, after diluting your sample, read the number in the side of the vial (rounding up if in between) and double that number.
 

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Here are today's numbers:

FC 4
CC 0
pH 7.6
TA 90
CH 625
CYA 90

I've been adding liquid chlorine but not enough, I guess. Regarding the FC up to 10, at what point is the FC too high to swim in? FC level had been up to 5, but I forgot to add chlorine yesterday and it fell to 4 today. Yikes! You're not kidding when you say to add chlorine every day.

I asked hubby to do the CYA test and he got 100. I'm feeling pretty confident in the 90 number. Have done it several times and watched some videos, which helped.

We're seriously considering the SWG. But we have a natural stone waterfall. Does that eliminate that option? I was reading on another thread about something called a stenner pump for liquid chlorine. Is that an option?

Thanks for all your advice so far!

PS - Misread the pool math figure for gallons. Should be 23K. I'll edit my signature as such. :cool:
 
The water is safe to swim in when FC is at or below your shock level, you can see the bottom and pH is in the 7's. For parties I normally bring my FC up to 10 the morning of and it keeps me from falling below the minimum.

I wouldn't drain it to lower the CYA, the CH would be a bigger concern as time goes on. You will want to monitor your CSI (Calcium Saturation Index) in Pool Math, try to keep it as close to 0 as you can.

I believe several folks on here have a SWG with stone water features. I'm sure someone else will chime in on that.
 
I think a swg would be fine for your pool and stone feature. I would do a good drain of 1/3 or so to bring down that CYA and drop that calcium a bit. It is too high but can be managed if you keep your pH down at the low end of normal (like 7.2 to 7.4) and use PoolMath to monitor your CSI.

Do you know how the calcium got so high so quickly?

Maddie :flower:
 
No, I don't know how it got so high so quickly. The fill water is pretty hard-325 ppm. We have been running the waterfall all winter as long as the pump is on. Trying to keep the pipes from freezing at the time. Not so much an issue now. So I don't know if the pool water is picking up calcium from the stone? Do the pucks have calcium in them as well as CYA?

Interestingly, I had the water tested at a pool store in December and everything checked within a normal range, except for phosphates. I got talked into their phosphate reducer (I know, I know).

I took another water test to the pool store in early March, and my calcium and CYA tested higher than normal. The only thing I did differently was add their product to the pool. BYW, the phosphates didn't come down at all. Hmmm. Which was probably good, because it led me to this forum and testing my own samples. It was probably only a matter of time before those pucks (and other things) caught up with me.

What do you think about using the soft water (225 ppm) to refill after every backwash, continuing to use liquid bleach to keep CYA and CH from climbing any higher?
 
Did they every have you add Cal-Hypo to your pool? Its usually sold as Pool Shock or something with Shock in its name? That adds Calcium to your water as well as Chlorine and is usually used as the Pool Store's crummy one time shock treatment.
 
All great tips and methods above. If I over-explain, please forgive me :)

Every pool is salty, whether chlorinated via SWG, liquid or solid sources of chlorine. Non-SWG pools drift to around 1000 to 1500 ppm salt or even much more. A SWG pool is kept around 3000 to 3500. The ocean is 35000 ppm salt (10 times saltier). The theory about SWGs affecting stone has not been demonstrated. Damage to stone is usually poor quality stone used in the first place, and sometimes from low pH caused by trichlor pucks (solid chlorine) without raising pH to offset the acidifying effect of the trichlor. If you keep your water chemistry reasonably correct, you will have little to no corrosion or damage arising from your choice of chlorination method.

The pool is safe for swimming (as mentioned, but I'll add the numbers)
1. You can see the bottom
2. pH is anywhere from 7.2 to 7.8
3. FC is between minimum and shock level per [FC/CYA][/FC/CYA]
- for 90 ppm CYA, your minimum is 7 ppm FC and your safe-swimming maximum is 35 ppm FC

The CYA ties up around 95% of the FC and holds it in an inactive form, ready to become active chlorine and do it's work as needed. The FC test includes all free chlorine, including the free chlorine that's tied up with CYA. A commercial pool with no CYA and 2 ppm FC (very common) will have far more active chlorine (the so-called "harsh" stuff) than your pool at 35 ppm FC.

According to PoolMath, your numbers are fine, provided you keep the pH around 7.6 to 7.8, though this will change as the water warms up. If you can gradually dilute it down that will be helpful, and yes, topping up with softened water will help. If rainfall is possible, that's even better. The calcium is arriving from your fill water, and gradually rises due to evaporation and refill. When the pool water evaporates, only water leaves the pool, not the salts that are dissolved in it, and the refill water brings more calcium, so calcium continues to rise. Anything you can do to reduce the incoming calcium will delay your need to replace water down the track.

You do need to do an Overnight Chlorine Loss Test to rule out algae. Free floating algae is not visible to the naked eye. When you see clumps of algae, or the water turns green, the algae has already exploded in growth rate. Your pool should be consuming very little chlorine while it's cold and no one is swimming. If the OCLT test comes up positive, you'll need to do a SLAM SLAM Process.

A SLAM can be done at 90 ppm CYA, but it will seem like an enormous amount of chlorinating liquid when you add the first dose! After that first dose, it's still more, but not as bad as the first dose. Usually, it's more practical to do a partial drain/refill to reduce CYA and make killing the algae a bit more more practical. As mentioned, removing and replacing 1/3 of the water will take CYA down from 90 to 60. You'll also get some benefit on the calcium level, be be aware it won't be as much of a change. If you're using 225 ppm CH fill water (the softened water), a 1/3 drain/refill will reduce your CH from 625 to just under 500. That's partly why people usually wait for the CH to get up closer to 1,000 ppm before doing a drain/refill to reduce CH. If you use your 325 ppm CH fill water, a 1/3 replacement will drop your CH from 625 to 525.

One of the great things about TFP is that the information is backed up by decades of experience on 10s of thousands of pools, and also explained with science. If there's anything not making sense, or you'd like to dig deeper, just let us know and we can point you to the background information.
 
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