First water test, sky high CYA!

JHookGiggle

Member
May 6, 2019
5
Smithton, IL
New homeowner of a house with a pool and spa. Been lurking on here for several weeks trying to wrap my head around what I’m getting into. Opened the pool over the weekend, due to cold and wet weather finally got to test the water today. Using a Taylor K2006 kit, results are below.

FC- 2.8
CC- .8
PH- 7.0
TA- 50
CYA- 100+ (it was way low on the sight glass, guessing somewhere around 150)

Based on my limited knowledge, everything is manageable except for the CYA. I believe the only fix is water replacement. The previous owners had an automatic chlorinator installed and used 3” trichlor pucks so I’m guessing that is the high CYA culprit.

The question is, do you think I’ll need to replace all the water, half, etc? Do run new water at the same time as you are dumping. Or do you drain a couple feet and then fill back up with new. I also assume there is no sense in worrying too much about the other chemicals until CYA is under control.

Any help is appreciated. Also, I’ll add some additional info on filter, pumps, cleaner, etc., tomorrow sometime.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,446
Laughlin, NV
Welcome to the forum!
100 is the limit of the CYA test, so you have to do a diluted test. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. Multiply the result by 2 for your CYA level.
Once you determine how much water you need to change out, we can describe a water exchange method that will not risk your liner.
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,587
Stuart/FL
J,

Welcome to TFP! Your assumption is correct that the previous owner's caused high CYA, we see this all the time. Please do add the rest of your info in the signature. It will help experts get you answers without a cycle of questions first. Once you get your CYA test done per Marty's advice he'll guide you through water replacement or exchange. Then you'll be rockin and rollin with a trouble-free sparkling pool!

Chris
 

JHookGiggle

Member
May 6, 2019
5
Smithton, IL
Yep, going to mess with it this afternoon. I'm thinking the easiest is to use the main drain and waste valve to drain the water. Only concern I have is the drain will take out water much faster than I can replace it. Is the vinyl ok to be exposed for a day or however long it takes to fill back up. The previous homeonwer had the liner replaced 2 years ago if that matters. I've also read where other have used a sump pump to drain the water from the deep end while adding new water in the shallow end (or vice versa based on water temps). Only issue with this is the time its going to take to replace 16,000 gallons of water.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,446
Laughlin, NV
It is far safer to use a sump pump and match flow rates in and out. You do not want your pool level to fall any closer than 18" above the shallow end of the pool.
Just for reference
You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.