New house - Need to SLAM but CYA levels high and can't replace/drain

CamilaP

New member
Aug 5, 2019
4
South of France
Hello everyone!

My family in law bought a country house with a pool last winter (pool came winterized) and my father-in-law opened it for the season but unfortunately did it without much knowledge or the right materials.
He was using Aquachek testing strips and thought they didn't work because the colors "were not chaging". I know the strips aren't great but definitely not so bad as to not work right out of the box. I realized upon arrival that every chemical/level tested was so low that the difference between the baseline and the results was difficult to see if you're not paying attention (FC:0, ph way below 6.8, TA non existent, CYA low). I let him know why they seemed to "not work", so he could work from there, because I thought he knew what he was doing.

However, based on the information I provided he kept trying to shock the pool and add Chlorine to raise FC levels (as it kept reading 0) but he did it with Dichlor 🤦‍♀️. As a result, in a couple of nights our CYA levels went from about 30 to close to 200, with no change whatsover to FC levels. We partially drained (1/3rd) and are close to refilling the pool but our CYA levels still seem to be stuck at around 150. I will be buying a proper taylor test kit, and liquid chlorine or household bleach from now on, but I need to figure out what to do so the pool is "swimable" for the season, knowing that there is now way in this European heat wave that I can re-drain/refill or exchange the pool water any more.

My current levels with the limited info on the Aquacheck strips is:

FC – 0
CC – Not testing
pH – 7.8
TA – 150
CH – Not testing
CYA – 150
Borates – Not using / Not testing

Do you have any tips, recommendations or ideas on how to proceed for the rest of the summer? Should I still attempt to SLAM? Will I need to eventually drain at least 2/3rds of the pool ?😭

Thank you for your help!
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
375
Verona, MO
Welcome to TFP! :)
Nice job filling out your pool information, it helps the experts guide you!

It will be very hard and costly to slam with a CYA at or over 100. An expert will surely chime in soon, but I would think you need to get that number down first. Surely cheaper and easier in the long run to swap out your water, lowering the CYA and bringing in fresh water. You could spend several weeks trying to slam.

Using pool math it looks like you would need to add 2 gallons and 1 quart of 6% bleach to get to an FC level of 15 from 0.
Trying to slam a 150 CYA might need approximately 9 gallons just to reach it let alone maintain it.
 

LoneWolfArcher

Well-known member
May 29, 2019
260
Michigan
I SLAM'd with a CYA of 120. It can be done but it will take a LOT of chlorine. I was in a similar boat where I could not drain and fill due to lack of a water source (our water is trucked in and we have a 1500 gallon tank for water for the house). Just go buy as much liquid chlorine as you can (I'd say you are going to need a minimum of 20 gallons on hand, and you may want more than that to make sure you have enough to maintain afterward).
 

Fast7

Well-known member
Aug 8, 2018
180
Plainfield, IL
How is the water? Any cloudiness or sign of algae?
Can you get FC to hold? Try to add enough chlorine to raise FC to 10 ppm using PoolMath with pump running.
Test FC after 15 minutes. If FC >5 and no other water issues, you can possibly maintain your pool this season without draining.
The only other option would be to simultaneously slowly drain and refill your pool if your water restrictions allow for it.
 

CamilaP

New member
Aug 5, 2019
4
South of France
Thank you all for your suggestions and ideas! It makes all the difference hearing from other people with experience and understanding what my options are (however extreme they may be) and also explaining it to my family in law (who are obviously NOT keen on draining the pool).

In the meantime I will get a decent testing kit, as recommended by TFP, to get accurate readings for CYA before doing anything else.

@LoneWolfArcher I've been having a really hard time finding liquid chloride in our area. Granulated Cal hypo seems to be more readily available, so If we do manage to drain (at least partially) and decide to SLAM I might be going with Cal Hypo instead. (Poolmath recomends between 5 and 10 pounds of it depending on the concentration, just to reach SLAM levels). Should I be concerned about the calcium levels?

@Fast7 once I get the proper test kit I may be able to try out your suggestion, thanks!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,052
Laughlin, NV
If your source of chlorine will be cal hypo, you will need to monitor calcium hardness and when it reaches a level making your CSI positive, you will need to drain 1/3 your pool volume or so and start over.
 

LoneWolfArcher

Well-known member
May 29, 2019
260
Michigan
Just say you are in France. Yeah I am not sure what options you have for LC, might even be regulated by the EU. Cal Hypo, as said above, adds calcium. @mknauss is an expert and so you'd be looking at a water exchange at some point. I'd really try to get LC somehow.
 

CamilaP

New member
Aug 5, 2019
4
South of France
While waiting for the taylor test kit to arrive, we brought some water in for testing at the pool place and got the following (dismal) results:

FC: 0.11
TC: 0.20
CC: 0.10
pH: 7.7
TA: 158
HARD: 83
CYA: 193 😱
CU: 0.3
FE: 0.0
Phosphates: 76

Thankfully water is mostly clear (only slightly cloudy and no weird coloring).

With this I have managed to convince my in-laws to drain and refill the pool. We will keep about 1/5 of the water so the remaining stabilizer, once refilled, will be just diluted enough to be in the 30-50 range.

However treating a newly refilled pool is out of my territory. Should I let it refill then proceed to treat? Should I SLAM? I want to make sure we do everything right this time! If there’s a pool school article on treating for the first time, please let me know.

BTW @mknauss, @cfherrman and @LoneWolfArcher the strongest concentration I’ve been able to find is 3.6% bleach. None of the pool stores we’ve been to carry liquid chlorine, and all other bleach in the supermarkets are even less concentrated. However we are lucky to have a vinyl liner pool and very low calcium levels in the water, so treating the refilled pool with 73% cal hypo should be okay? We could attempt to could do daily maintenance with 3.6 bleach afterwards.

Again, thank you all for your help. You’ve been a godsend!
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,052
Laughlin, NV
The cal hypo use will be fine as long as you monitor the CH and keep the CSI from rising to above 0.3.

When you refill, use the cal hypo to slam. Be sure you mix it in very well as it can stain your liner if it sits on it. With the high TA you may see cloudiness. Lowering the TA to under 100 ppm would be best.
 

CamilaP

New member
Aug 5, 2019
4
South of France
Happy to report that we were able to finally refill the pool yesterday. Started slamming yesterday, with checks and adjustments every two hours or so, and mixing well per @mknauss' instructions. This morning after 8 hours of no adjustments/additions, Free Chlorine = Total Chlorine 💪. CH down to 110. TA around 50. The water is perfectly clear.

I will keep monitoring, brushing and vacuuming and I will perform an OTCL test tonight. I'll keep you posted!
 
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