Draining Pool Due to High CYA, TC, CH....what to do with water once refilled

J Level

Member
Mar 29, 2021
5
Tucson, AZ
Dug in deep to learn about new pool chemistry and up keep after recently buying house with pool. Tested water (now usingTF-100 kit), in store at first, and have come to the conclusion I need to rent submersible pump and drain. Tested for partial drain potential - and based on testing, it would require at least 3/4 drain to start maybe getting in ideal ranges for CYA, TC - and who knows. Current chemistry....

CYA - 150-200
FC - 25 - 30 (interestingly, keeps going up even though removed chlroine tabs, only source over two weeks ago - maybe b/c its getting warmer, chlorine is getting released from CYA)?
CC - 0
CH - 700-1000
PH - 7.3 (i brought this up w/chems before realizing)
ALK - 200 (Up from 90 a week ago. Haven't added anything since. Also maybe warm weather impacting)
Phosphates - 3500 (store tested a few times, i know they shouldn't matter, but i believe suggestive of pretty high TDS - and in general not great to have in there).

Based on these numbers, thinking to just drain completely and start new. Guessing prior homeowner didn't use pool much/at all...so was happy just popping in Chlor tabs in a floater to keep it high/looking clean.

A bit nervous about performing full drain, but living in AZ not worried about high water shelf causing lift - and have wash area i can drain into far away from pool. Will look to drain late afternoon/into evening (cooler weather with plaster) -- and refill with 3-4 hoses running into it.

Big question - what do I do with the newly filled pool water to stabilize and get it synch? I'm sure pool store folks could tell/sell me a bunch of stuff -- but part of the reason we're all here I believe is to cut through some of that noise. I've read the School - Chemistry stuff, also on starting a new pool - but seems to be geared towards brand new construction plaster. If there's and article/link I'm missing - appreciate tagging. Thanks in advanced. With warm weather the teenagers are getting restless for the 'all clear' shout out!
 

Cwiggs

Well-known member
Aug 31, 2019
141
Phoenix, AZ
Pool Size
21000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60 Plus
If you haven't read the draining wiki page I'd give it a read.
FC - 25 - 30 (interestingly, keeps going up even though removed chlroine tabs, only source over two weeks ago - maybe b/c its getting warmer, chlorine is getting released from CYA)?
The CYA by itself won't introduce FC, if you aren't putting chlorine in it shouldn't go up. The FC is so high you might not be getting an accurate measurement.

Your CH and CYA is high so a drain/refill is probably in order. Once you have fresh water in you just want to re-balance the chemicals in your pool. You should buy bleach/liquid chlorine, dry stabilizer (CYA), and some most likely muriatic acid. You might need something to raise the pH/TA if your fill water is low in TA.

The first thing I would do is to test your fill water and report back with the results.
 
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Enumjon

Well-known member
Apr 30, 2020
99
Tijeras, NM
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
I was in the same situation as you last year. Inherited a pool with water that was beyond repair. I also live the southwest, so have extremely hard water with very high TA. As recommended above, once it was filled I got the chlorine level up. Then I started working on lowering the TA - dropped it from over 600 to about 130 last year, hope to get it to a stable place this year. Have been lowering my CH by only filling the pool with softened water, and snow in the winter.

As an aside, my testing numbers were crazy for a week or two after the refill. My testing procedure stayed the same, but my numbers started very, very high and then dropped quickly. So, get the chlorine up but wait a few weeks to trust the other numbers after you fill.
 

red-beard

Gold Supporter
May 27, 2019
974
Houston, TX
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite Pro (T-15)
First, test your fill water for CH, just so you know what you have.

At 150-200 CYA, you might actually be much higher. My suggestion is a Full drain. That is what I did when mine was too high. You are starting over and you can fix everything at that point.

Have Liquid Chlorine, Muriatic Acid and Cyanuric Acid (CYA) granules on hand. I add the Liquid Chlorine to 30 CYA ppm SLAM levels (12 ppm, use Pool Math) while I am filling. I used 2 submersible pumps (I own) and was able to drain my pool in about 16 hours. I used three hoses and was about to fill it in less than 12 hours. Once filled, turn the pool pump on and leave it, on, circulating 24/7. Check the water after a few hours for FC level with your test kit. But do the next step as soon as you have the pumps running.

Use Pool Math to calculate how much CYA you need (30 PPM is a good start, but very sunny locations may need more). Put about 3/4 of that amount into old socks and tie off. Put the socks in front of return jets. You might use zip ties on pool brushes and net handled to hold the socks. Position the jet so it hits the lower part of the sock. Squeeze the socks periodically (every few hours) to move the CYA down. If you do it right, the CYA should dissolve in a matter of hours. It will NOT dissolve in a bucket of water!

Once the CYA is dissolved, wait 24 hours (while still circulating). Check the FC, pH and CYA level. If the CYA level is good, adjust your pH with muriatic acid if necessary. If you need more CYA, run another sock with the other 1/4 or calculated amount. It is better to add CYA in steps, since you can only get it out by draining.

About this point, do a full run of tests (FC, pH, TA, CH, CYA) and make further adjustments. for higher TA, use baking soda. Lower pH, use Muriatic Acid. Higher pH, Washing Soda (Sodium Carbonate).

If the CH is low, you can use calcium hardness increaser. I usually used Cal-Hypo (Calcium Chlorine powdered shock) as my chlorine source which also raises the CH. It is extremely stable and easy to use, as long as your CH is low. You will want to get into the 250 ppm region with a calcium hardness increaser, though.
 
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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
37,186
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
what do I do with the newly filled pool water to stabilize and get it synch?
Chlorine is king. Add 3ppm FC worth of liquid chlorine while filling.
Add 40 ppm CYA worth of stabilizer using the sock method.
Test pH and adjust to keep in the 7's. As you maintain your pH in the 7's. your TA will come down. Test TA every time you need to add acid to lower pH.
Be sure to use PoolMath for calculating your chemical additions.
 
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Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
6,943
NY
was in the same situation as you last year
Goodness gracious I LOVE this place. Full blown real world experience from real people who learned the easy way to do things and not some seasonal teenager reading off a computer print out. Or even worse, the same seasonal teenager that hasn’t met their sales targets this week.

Ask away @J Level at any stage with any questions. It may seem that you are being a ‘pain’ at times but It’s far easier for us to fix one problem instead of 2 or 3 when you over correct. Ask and then do. :)
 
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Cwiggs

Well-known member
Aug 31, 2019
141
Phoenix, AZ
Pool Size
21000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60 Plus
Then I started working on lowering the TA - dropped it from over 600 to about 130 last year
Wow, that is high TA. Where I'm at the TA is high, but not that high, I think my fill water is 130 but I'd have to double check.

The CH here is also high, but not so much that a pool with new water is too high. It's high enough that after about 2 years it's higher than I'd like.

I'm not sure where OP is in AZ but if he is in the Phoenix metro area the TA probably isn't over 600.
 

Kevinr14

Well-known member
Mar 8, 2021
122
Chandler, AZ
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
Wow, that is high TA. Where I'm at the TA is high, but not that high, I think my fill water is 130 but I'd have to double check.

The CH here is also high, but not so much that a pool with new water is too high. It's high enough that after about 2 years it's higher than I'd like.

I'm not sure where OP is in AZ but if he is in the Phoenix metro area the TA probably isn't over 600.

I'm in chandler and my fill water TA was 120ppm the last time i tested it.
 
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salinda

LifeTime Supporter
Feb 25, 2008
141
Los Gatos, CA
I have a similar issue in Northern California. My pool has been high with CH around 700-800 every year and every winter I get rainwater dilution which lowers it again to start the season. This year not so much. Now my CH is 1200. We are in drought so I am paying for an RO purification service to come exchange the water in my pool.