FC loss due to no CYA or algae?

[Pepperdinegal]

Okay, so I used a RO truck to refresh my pool water last weekend and am now in the process of rebalancing my chemicals. Current readings are as follows:

FC : 4
pH : 8.0
TA : 50
CYA : <30
CH : 200
Salt : 3400

I added 3 gallons of liquid stabilizer yesterday morning about 10am. I think I need another gallon and a half to get to 70, but I didn’t want to overdo it. The problem is, my CYA is still not reading. I know it can take a couple days to dissolve but my current issue is that the FC isn’t holding in the pool. I added a gallon of liquid chlorine yesterday at 9am and it was all gone by 7pm, so I added another gallon to get it up to 5 overnight. This morning it was back to 4, even with the pump and SWG running all night. Now I’m questioning whether I’m fighting some sort of algae in the water or if it’s just getting eaten up due to lack of CYA. Pool is perfectly clear with no debris. Am I just panicking and overthinking?

Also, thanks to whoever told me to hold off on the borax to bring my pH up. It was 6.8 on Sunday and is already back up to 8.0 just from aeration.

 

[Saturn94]

added another gallon to get it up to 5 overnight. This morning it was back to 4, even with the pump and SWG running all night.

This sounds like chlorine is fighting something in the water.

 

[mknauss]

Liquid stabilizer should be in the water pretty quickly. Can we assume you thoroughly washed the product out of the container?

I would not take the CYA up to 70 ppm. No real need going into fall/winter. What you have should be sufficient.

 

[Pepperdinegal]

Yes. Rinses the jugs several times. And then brushed. Should I slam just to be sure?

 

[mknauss]

Taking your FC to 20% of your expected CYA would not hurt.

What stuff did the RO company add to the pool water?

 

[Pepperdinegal]

I didn’t let them add anything. I told them I would do the rebalance.

 

[mknauss]

Hopefully that is true.
Add some liquid chlorine. See if things resolve themselves today.

 

[Pepperdinegal]

I was out there the entire time he was taking all the lines out. He didn’t add anything. He wrote down what he thought I should add but ignored and took TFP advice instead.

 

[Pepperdinegal]

What are you thinking he could’ve added that would mess with my numbers?

 

[mknauss]

An ammonia based algaecide would create an unusual FC demand until consumed.

 

[Pepperdinegal]

He def didn’t dump anything into the pool.

 

[Pepperdinegal]

So I’ll bring the FC up to 12 with liquid chlorine and keep it there for 48 hours then retest CYA. Sound like a good plan?

 

[mknauss]

Good plan.

 

[mknauss]

Also suggest checking the date code on the liquid chlorine. It can be degraded.

 

[Pepperdinegal]

Okay, so I don’t know what’s going on. Last night I tested after sunset and my FC was at 7 so I added a gallon and that should’ve brought my FC up to 11.5/12. This morning I get up and go check and my FC is back to 8. CYA still isn’t registering. What is going on??

 

[mknauss]

What liquid chlorine are you using? What is the date code on it?
What stabilizer did you add? How much did you add?

 

[Pepperdinegal]

Usually I use the liquid chlorine from Home Depot but yesterday I got the 12.5% Pro Chlorinator from Leslie’s and the date is 2424822:34

For liquid stabilizer, I used Natural Chemistry Instant Conditioner from Amazon and put in 4 gallons.

 

[mknauss]

The chlorine should be at least 10% strength.
That should be enough stabilizer to show up.

Hard to say what is going on.

I would be careful adding any more stabilizer.

 

[Pepperdinegal]

I’m nervous to add more liquid or dry stabilizer at this point bc I don’t want to overshoot 60/70.

 

[mknauss]

Verify your testing procedures.