Inheriting High CYA Pool

spinPHD

Well-known member
Apr 20, 2017
500
Phoenix
Greetings everyone. A month ago, I moved into my first home and it has a pool. Unfortunately, the pool I inherited had a high CYA. My testing strips say it’s over 180. (Before I get negative comments on using strips, I have a Taylor K-2006C on the way). This is because the previous owners had a pool guy that was too incompetent to read the forum and he was so bad that he placed the pucks directly in the basket of the top skimmer.

I know that the recommended way to lower the CYA is to drain the pool or at the very least drain a portion of the pool and refill. However, with temps already in the high 90s in AZ and the pool staying clear despite the high readings, I am struggling to convince the Mrs. that I need to drain the pool.

I think I may be able to convince her that I will drain (via backflush) and fill with a hose at the same time so the water level doesn’t go down. I have read some people say that this method is not effective because when you drain you will be losing some of the “good water” that you put in with the hose. However, doesn’t the CYA from the old water immediately mix in with the new water and spread it out evenly? So even if you pump out the water that was just put in, it will take out the same amount of CYA?

Lastly, if I am unable to drain the pool now, should I just keep using the pucks and trichlor until I can drain the pool? Based upon my lurking, it would take an unreasonable amount of bleach to get the chlorine levels to where I need them.

Thanks for your time,
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
11,438
Bedford, TX
S,

Welcome to TFP... A Great resource for all those husbands hesitant to drain their pools... :shark:

I suggest you wait until you new test arrives. Since "guess" strips are almost useless, your actual CYA level could be much less, or much more than you realize.

Once you know the real number it will make the decision easier..

Thanks for posting,

Jim R.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,122
Franklin, NC
If your pool is clear and once you get your test kit you can determine via an Overnight Chlorine Loss Test that there is nothing growing in the water then there is no dire emergency.

I inherited my pool with CYA in the range of 250. I maintained the proper level of FC for that high a CYA and moved forward.

Things that I did:

- Backflushed my sand filter for almost any reason and ran it longer than usually is necessary.

- Vacuumed to water if I saw stuff on the bottom of the pool.

- Did a few small/partial drain & refills

- Rigged up a system to capture rain water form my downspout and directed it into the pool

Over two years I slowly reduced my CYA to the point that this year I had to add it as the water began to warm.

The key is the proper amount of FC all the time. Let it slip and allow algae to get a foothold and you will need to SLAM.

If your CYA is really 180 then your FC must be kept at 14 as a minimum and I would recommend 16 as your target. The problem you will have is the pH test reads incorrectly high at FC above 10. To test pH you will have to allow the FC to drop, test and raise the FC immediately. It can be down but it takes watching it like a hawk.
 

spinPHD

Well-known member
Apr 20, 2017
500
Phoenix
If your pool is clear and once you get your test kit you can determine via an Overnight Chlorine Loss Test that there is nothing growing in the water then there is no dire emergency.

I inherited my pool with CYA in the range of 250. I maintained the proper level of FC for that high a CYA and moved forward.

Things that I did:

- Backflushed my sand filter for almost any reason and ran it longer than usually is necessary.

- Vacuumed to water if I saw stuff on the bottom of the pool.

- Did a few small/partial drain & refills

- Rigged up a system to capture rain water form my downspout and directed it into the pool

Over two years I slowly reduced my CYA to the point that this year I had to add it as the water began to warm.

The key is the proper amount of FC all the time. Let it slip and allow algae to get a foothold and you will need to SLAM.

If your CYA is really 180 then your FC must be kept at 14 as a minimum and I would recommend 16 as your target. The problem you will have is the pH test reads incorrectly high at FC above 10. To test pH you will have to allow the FC to drop, test and raise the FC immediately. It can be down but it takes watching it like a hawk.
This is exactly what I needed to hear. I started to feel like it was helpless unless I drained immediately. It's good to hear that I can still start using liquid chlorine now, and over time I can bring the CYA down overtime by back-flushing and dilution.
 

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
10,122
Franklin, NC
This is exactly what I needed to hear. I started to feel like it was helpless unless I drained immediately. It's good to hear that I can still start using liquid chlorine now, and over time I can bring the CYA down overtime by back-flushing and dilution.
You can, but you have to be diligent. Either a SWCG or liquid chlorine only. No tabs for vacation, no shock because it's easy.

This includes vacations. Start thinking now of who can come over and pour chlorine in your pool while you are gone.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,382
Pleasanton, CA
I think I may be able to convince her that I will drain (via backflush) and fill with a hose at the same time so the water level doesn’t go down.
I have had good success with this method but I supply water to a skimmer (that is shut off) in the shallow end while drawing from the MD only in the deep end. This helps to keep the water separated. I was able to replace about 90% of the water without mixing.
 

triptyx

TFP Guide
Apr 12, 2016
1,495
Tucson, AZ
That said, we're suppose to have a "cold front" late next week. If the weather actually does get into the 80's, and you're willing to use a hose to keep the exposed plaster moist, you could look at doing a partial drain/fill then. I did this in April last year after inheriting a pool that had similar CYA issues. I used a rented submersible pump from a local hardware store to get the water out fast.

mas985's technique also worked very well for him, so that's definitely another great option.
 

spinPHD

Well-known member
Apr 20, 2017
500
Phoenix
That said, we're suppose to have a "cold front" late next week. If the weather actually does get into the 80's, and you're willing to use a hose to keep the exposed plaster moist, you could look at doing a partial drain/fill then. I did this in April last year after inheriting a pool that had similar CYA issues. I used a rented submersible pump from a local hardware store to get the water out fast.

mas985's technique also worked very well for him, so that's definitely another great option.
My pool is pebble tec. I didn't think you needed to worry about keeping it moist when you drain.
 

triptyx

TFP Guide
Apr 12, 2016
1,495
Tucson, AZ
It's still plaster based (all those pebbles are embedded in and held together with plaster), so you do still need to be concerned about keeping it moist and not letting it "bake" in the sun, as well as ensuring you're keeping the correct chemical balance for plaster pools. :)
 

gerg

Active member
Jul 18, 2016
27
Philly Suburbs
You could do it over several stages. For example if you drained 10% of your water and then filled it right back up you'd be at ~160, do it again you'd be at ~145, ~130, ~115. 10% of the water isn't really that much...you could still swim in it.
 

borjis

LifeTime Supporter
Aug 19, 2014
2,707
Pacific NW
I have had good success with this method but I supply water to a skimmer (that is shut off) in the shallow end while drawing from the MD only in the deep end. This helps to keep the water separated. I was able to replace about 90% of the water without mixing.
I did this as well recently. Had a small bout of metals in the water when I added the first chlorine of this year.


For my last house/pool the previous owner also had pucks in the skimmer.

after I got the TF100 test kit, i had to do a dilluted CYA test and it was reading 350+
The ph was also not good at 6.8

I did 2 partial drains / refills down to the pool light and started draining it at 6pm once
the sun was no longer showing on the plaster. It was drained to the light by 9pm
and filled up to the water line by 7am the following morning.

This took the cya down from 350+ to a much more manageable 70.
The water was really expensive in that area and I ended up selling the place so that's how I left it.
 

Rossterman

Well-known member
Jun 5, 2016
241
Martinez, CA
Some people have used a tarp (attached across,the top and vertically with weights on the bottom) in the pool to keep new water additions from mixing with the old thereby improving the drain and fill process.
 

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