Attempted to shock pool, but measuring only 2ppm FC

[pzampino]

First, I've been taking care of this pool for about 9 years now, and having quite an easy time of it thanks to the wealth of information available here.

So, per my usual Spring routine, I've:

• Vacuumed the pool (27,000 gal)
• Re-installed my salt cell
• Balanced the pH/TA (~7.5 / 60ppm)
• Added CYA (overshot a little, to between 90-100)
• Added 8 121oz jugs of 7.5% bleach (around dusk)

The problem is, when I measure the FC (using FAS-DPD), it's only reading 2ppm (instead of something closer to shock level as I expected), and there is no combined chlorine.

Are my chemicals bad? Is there something else I've forgotten since last season?

 

[PoolStored]

Can you post a full set of results before you did anything to the pool?
Did you test CYA before adding CYA? What did it test?
How long after adding the bleach did you test 2ppm?
Post a picture of the date code of the bottle.
What brand bleach? When did you buy it?

I'm thinking bad bleach.

Did you test CCs before adding any chemicals? Does the pool "smell" right (i.e. no chlorine smell?)

 

[Lake Placid]

The problem is, when I measure the FC (using FAS-DPD), it's only reading 2ppm (instead of something closer to shock level as I expected), and there is no combined chlorine.

If you’re measuring 0 CC and this measurement is accurate, I’d favor bad bleach over ammonia….

 

[PoolStored]

If you’re measuring 0 CC and this measurement is accurate, I’d favor bad bleach over ammonia….

Yeah, my conclusion too...I updated. I have seen the CC come down with an initial treatment of LC. We'll see if they tested CC first, what the CYA was before adding, and if the pool smells...

 

[pzampino]

I hadn’t considered bad bleach, but it makes the most sense. The water normally smells rather strongly after adding that quantity, and it doesn’t at all.

I purchased it at Home Depot. I can’t recall the brand at the moment, but it was not Clorox or a “big brand” I recognize. I’ll have to check the remaining bottles later. The recycling truck had already picked up the empties.

 

[Lake Placid]

I hadn’t considered bad bleach, but it makes the most sense. The water normally smells rather strongly after adding that quantity, and it doesn’t at all.

I purchased it at Home Depot. I can’t recall the brand at the moment, but it was not Clorox or a “big brand” I recognize. I’ll have to check the remaining bottles later. The recycling truck had already picked up the empties.

Probably their HDX branded liquid. They have a bad habit of shelving stock in the fall for the winter and putting it out again in the spring….meaning it’s likely many many many months old.

 

[Sws]

Probably their HDX branded liquid. They have a bad habit of shelving stock in the fall for the winter and putting it out again in the spring….meaning it’s likely many many many months old.

Can confirm. Seen it myself.

They pallet the left overs, wrap them then put them on a high shelf until the season starts again.

 

[Lake Placid]

Can confirm. Seen it myself.

They pallet the left overs, wrap them then put them on a high shelf until the season starts again.

Yeppers OP probably bought gallons of saltwater unknowingly.

 

[pzampino]

Thanks again for pointing to the bleach as the culprit. It took some arguing with an individual at the customer service counter at Home Depot, but they did eventually give me a refund for the defective bleach. Her initial response when I explained how I know it was bad bleach: “Uh, that’s for laundry!”

I’ve since picked some up from an alternative source, and the FC is now where I expected it to be. I think I’ll pass on the HDX brand bleach from Home Depot in the future.

 

[Lake Placid]

I’ve since picked some up from an alternative source, and the FC is now where I expected it to be. I think I’ll pass on the HDX brand bleach from Home Depot in the future.

If it’s convenient for you and the price is right, don’t pass on it. The chlorine itself is generally just fine. Just be aware of their stocking methods and check the date codes to ensure it’s fresh when you buy.

 

[Sws]

Thanks again for pointing to the bleach as the culprit. It took some arguing with an individual at the customer service counter at Home Depot, but they did eventually give me a refund for the defective bleach. Her initial response when I explained how I know it was bad bleach: “Uh, that’s for laundry!”

I’ve since picked some up from an alternative source, and the FC is now where I expected it to be. I think I’ll pass on the HDX brand bleach from Home Depot in the future.

Its what I typically use. Just wait for the 2025 shipments.

Chlorine Date Code Decoder - Further Reading

www.troublefreepool.com

 

[Newdude]

I haven't seen liquid chlorine at HD/Lowes under $7 /gal since 3 years ago. Lowes is pretty consistant but HD is all over the place at $7 to $10. And the dates usually make me walk away.

Walmart has been the same $5.67 this whole time with current batches. Sometimes I have to dig a little like buying milk or yogurt, but no biggie.


I spit out my coffee at Lowes the other day, their 5% 'outdoor cleaner' is in 5 gal jugs..... for $55.