SLAM process - Added 4.4 gallons of 6% bleach... FC barely increased??

[BurlesonTXpool]

Hi all,

First post here. Been lurking around and reading as much as I can to figure out how to maintain a crystal clear pool on my own.

So I've tested the water chemistry a few times with the K-2006 FAS-DPD test. Here are my most recent results:
FC: 0.4
CC: 1.2
PH: 7.6
TA: 55
CH: 300
CYA: 55

Pool water is pretty clear, not much if any algae present aside from small stubborn areas on the walls/bottom.

To begin SLAM process according to pool math calculator (double checked & confirmed with SLAM Chlorine/CYA chart) I added 4.4 gallons of 6% bleach (purebright bleach I just bought yesterday from floor & decor). I brushed the pool and put the pool vacuum in shortly after adding bleach.

I added the bleach around 10:00am and checked the chemistry again around 12:00pm (2 hours later). My FC only increased to 2.0. I have my pump set to complete a full cycle within about 6 hours. I double tested to be sure I got an accurate reading and followed the K-2006 FAS-DPD testing instructions.

Any ideas why the FC had only increased by 1.5, and did not increase to my SLAM FC target level of 22?
SLAM process says to check the water chemistry at least twice a day but not more than once an hour. Should I wait a certain amount of time to check FC level after beginning SLAM?

 

[Newdude]

Check the date code. It’s Julian and will be 2 numbers for year like 21 or 20, and 3 more #s for the day of the year. More #s usually follow and will be manufacturer info like plant location or batch #. But the first 5 are the important ones. 21010 is really 21/010 or Jan 10th 2021 for example.

Even if it’s less than 3 months old, it may have sat on a pallet in the sun and degraded faster than usual.

 

[Newdude]

Should I wait a certain amount of time to check FC level after beginning SLAM?

15-20 mins is plenty to mix it with the pump running. But Ya did good !!! You tested to see that there was a need. You added accordingly *and then tested again!!!!* to prove it. Which in this case disproved it but it’s just as important. Well done.

 

[PointeTaken]

Agree with @Newdude. It's likely that your bleach has lost its potency. The only other explanations would be inconsistent testing methods (which you appear to have eliminated) or miscalculated pool volume (which would have to be off by a near-impossible amount given the amount of bleach we're talking).

 

[mknauss]

If you tested a CC of 1.2, very likely the chlorine was consumed by the organics in the pool water.

 

[PointeTaken]

If you tested a CC of 1.2, very likely the chlorine was consumed by the organics in the pool water.

20 ppm worth in 2 hours? I'm not refuting, I've just not ever experienced it myself.

 

[Newdude]

20 ppm worth in 2 hours? I'm not refuting, I've just not ever experienced it myself.

It could be a lot of things. A real bad algae bloom is one, Ammonia is another (less likely).

verify your chlorine to prove/disprove the easiest culprit

Know what else you did right ???

you came here to ask. Not the:

PB: See my store and spend $300
Pool Store: That’ll be $300 and it won’t work
FB: Your mother is promiscuous
Web Md: Sorry it’s terminal stage IV.

 

[BurlesonTXpool]

It could be a lot of things. A real bad algae bloom is one, Ammonia is another (less likely).

verify your chlorine to prove/disprove the easiest culprit

Know what else you did right ???

you came here to ask. Not the:

PB: See my store and spend $300
Pool Store: That’ll be $300 and it won’t work
FB: Your mother is promiscuous
Web Md: Sorry it’s terminal stage IV.

Thanks for all the input. The FB and WebMD solutions are hilarious.

 

[BurlesonTXpool]

Check the date code. It’s Julian and will be 2 numbers for year like 21 or 20, and 3 more #s for the day of the year. More #s usually follow and will be manufacturer info like plant location or batch #. But the first 5 are the important ones. 21010 is really 21/010 or Jan 10th 2021 for example.

Even if it’s less than 3 months old, it may have sat on a pallet in the sun and degraded faster than usual.

Just checked... 20119.
Looks like that would be Jan. 19th 2020, and the bleach likely lost most of its potency.

Didn’t even think to check that. Now to find a reliable bleach source .

Thanks for the help

 

[Newdude]

Didn’t even think to check that. Now to find a reliable bleach source

It’s usually the easiest reason why you didn’t hit your target. If the dates are good then it’s time to explore further. But for today ??? WooHoo !!!

HD/Lowe’s have 10% HDX in the pool section and Walmart has 10% Pool Essentials in their pool aisle.

 

[mknauss]

Just checked... 20119.

That is the 119th day of 2020. So mid April.
6% bleach does not degrade all that much more. You still had at least 3%. So you do have organic consuming chlorine.

 

[BurlesonTXpool]

That is the 119th day of 2020. So mid April.
6% bleach does not degrade all that much more. You still had at least 3%. So you do have organic consuming chlorine.

Pic quality isn’t very good, but there is some small organics that I couldn’t get with the skimmer. Based on the pic, curious if even a small amount of organics could be consuming that much chlorine?

Thanks for the input!

 

[mknauss]

Pool water is pretty clear, not much if any algae present aside from small stubborn areas on the walls/bottom.

That is what you posted originally. If you can see algae, the pool water is full of it. You just cannot see it, yet.

 

[PointeTaken]

Now to find a reliable bleach source

If you do decide to go with HDX from Home Depot, as @Newdude suggested, just be aware that many Home Depot stores place their pool stuff - including bleach - outside in the garden center. Unless the date codes are very recent, I’d avoid any bleach jugs that are shelved outside. Otherwise you’ll be paying for more water than advertised. Personally, I’ve found the greatest ROI with the Pool Essentials 10% bleach (sold as “Pool Chlorinating Liquid”) from Walmart. Around here at least, it’s the cheapest you can buy, always stored inside, always in stock, and almost always a date code inside of 30 days or so.