RAPID Chlorine Loss during SLAM

[kafox001]

Hello, I've been slamming since last Friday (7/7) when I noticed some green algae spots in corners of the pool. I had previously been slacking a bit due to several rainy days and let my FC get below minimum unfortunately.

Today:
FC 12
CC 0
PH 7.2
TA 80
CH 180
CYA 40

Pump running 24/7 at 1725RPM. I have been brushing, haven't noticed any algae spots in a few days and made sure to brush under stairs, ladder etc. Robot runs daily and is emptied daily. Have been checking FC as often as possible (with an infant at home) and topping up to SLAM level as needed. Pool water is clear but I do get a lot of tree debris daily. Emptying skimmer basket multiple times a day and have backwashed once during the SLAM and added DE to my sand filter.

The last few days I have been noticing rapid FC loss as soon as sun hits the pool in the morning. Yesterday I went from 15 FC at 11am (when the sun came out from behind clouds) to 3 FC at 1:45pm. Today I went from 20.5 FC (overshot a bit last night) at 7:15am to 12 FC at 10:45am with sun out all morning.

I've done the CYA test over and over again on multiple days and I am as confident as I can be that it's 40. I am not passing OCLT so there is definitely something still consuming FC but the rapid loss due to sun is puzzling me.

As you all know, liquid chlorine prices are nuts this year so having to continually buy more is quite stressful. Any help is appreciated. Thanks!!

 

[Texas Splash]

FC loss is somewhat expected during the SLAM Process, but yesterday's drop from 15 to 3 is alarming. If your testing was accurate and consistent, that's enough drop to think there's something odd in the water. If you have any doubts about your FC testing (10 ml sample size, one scoop of power, divide result in half, etc) let us know. If not, then I would review the following:
- Pool light (if installed) removed if it is a large light set into a niche.
- Ladders or steps removed?
- Main drain area/cover inspected?
- Inspect behind the weir flap/door and under the poolside skimmer lid?

I wouldn't worry too much about using DE until you pass the Overnight Chlorine Loss Test.

Hope that helps.

 

[kafox001]

FC loss is somewhat expected during the SLAM Process, but yesterday's drop from 15 to 3 is alarming. If your testing was accurate and consistent, that's enough drop to think there's something odd in the water. If you have any doubts about your FC testing (10 ml sample size, one scoop of power, divide result in half, etc) let us know. If not, then I would review the following:
- Pool light (if installed) removed if it is a large light set into a niche.
- Ladders or steps removed?
- Main drain area/cover inspected?
- Inspect behind the weir flap/door and under the poolside skimmer lid?

I wouldn't worry too much about using DE until you pass the Overnight Chlorine Loss Test.

Hope that helps.

Thank you. I am confident in my FC testing though I have always used two scoops of powder as specified in the Taylor directions?

-No pool light
-Steps and ladders not removed. I'll try to tackle this tomorrow.
-No main drain
-Skimmer/weir/foam looks good though I did see a speck of green on some pool putty epoxy I used to seal a suspected leak around the skimmer box years ago. Anything I can do for this besides pour some chlorine on it and scrub?

 

[Texas Splash]

-Steps and ladders not removed. I'll try to tackle this tomorrow.

That could be the culprit. We'll see.

I have always used two scoops of powder as specified in the Taylor directions?

That's for people use use the 25 ML water sample size then multiply by 0.2. If you use the 10 ML sample to multiply by 0.5, then one generous scoop of powder is sufficient and accurate. Should help make your powder last a bit longer.

 

[kafox001]

That could be the culprit. We'll see.


That's for people use use the 25 ML water sample size then multiply by 0.2. If you use the 10 ML sample to multiply by 0.5, then one generous scoop of powder is sufficient and accurate. Should help make your powder last a bit longer.

Will update here on the ladder and steps hopefully tomorrow. Ladder is easy to remove but the steps are a pain.

Taylor instructions don't differentiate between 25ml and 10ml as far as powder scoopage but I'm on board with saving powder!

 

[dfwnoob]

That's because Taylor wants to sell you more reagents

 

[kafox001]

Only lost 2 FC overnight so that's progress!

@Texas Splash when I take the ladder and stairs out, what's the procedure? I know to inject them with chlorine, but do I need to drain the water from them first? How long should the chlorine stay in? Should I rinse them out with water after? Do they need to stay out of the pool until slam is complete or can they go back in after chlorine treatment?

And anything I can do about the epoxy putty I mentioned in a previous post?

Thanks so much!

 

[Texas Splash]

what's the procedure?

All of the above really. Getting them out is usually the most difficult. Some items can be dissembled, if not completely maybe partially. Then you have better access to clean. For those items that are one piece with no way to disassemble, then you look for any access areas to inject some chlorine into the cavity(s). I would leave them out until the SLAM is over. Hopefully you find see the obvious culprit and your FC will hold much better with the troublemaker removed.

 

[kafox001]

Ok steps and ladder are out.

Steps were basically clean. Maybe a tiny bit of pollen build up in one or two crevices but nothing else. Nothing but clean water coming out when I hosed out the holes. I still flushed out with chlorine the best I could and drilled additional/bigger holes to promote circulation.

Ladder did have a couple globs of green come out but not the smoking gun I was expecting. Drilled bigger holes and also flushed these with chlorine.

I also dove around and scrubbed every crevice/corner, return and all around/inside the skimmer.

I guess let's see how FC holds unless you can think of anything else to check?

 

[kafox001]

 

[Texas Splash]

Very good. Now it's just the chlorine, organics, and sunlight. I don't see anything else in the pool that could effect your FC. Curious to see how your Overnight Chlorine Loss Test goes tomorrow.

 

[kafox001]

Got a lot of rain overnight (and all the debris that brings with it) so lost 3 FC overnight

 

[Texas Splash]

lost 3 FC overnight

That's a shame. Rain shouldn't have much impact on chemistry unless it's a long torrential type rain. But that's okay, try to maintain the required FC level and follow the notes form the SLAM Process.

Last I recall you listed the CYA as 40, so you might want to verify to ensure you are at the proper FC level. See below if it helps.

CYA Testing:
Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, then gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.

 

[kafox001]

Thanks - yea I understand the rain itself doesn't affect FC but it's all the junk that the rain brings with it. As you can see in my previous pic we have some BIG trees over the pool. Pic below is like 3 hours of skimmer collection from the other day so it's always a battle.

I have never been confident in my CYA test abilities but I will try again today and try to verify 40 CYA. I have been aiming for 16 FC but sometimes I accidentally overshoot a bit. Last night was 18.5 FC to 15.5 FC this morning, for example.

 

[kafox001]

Passed OCLT overnight, woo!!

I didn't get a chance to retest CYA because it's been pretty overcast, but I'll do it the next bright and sunny day.

What should be my next step? Put stairs and ladder back in and pass another OCLT? Water has been clear for days and CC has been .5 or less consistently.

 

[kafox001]

Passed another OCLT with just the ladder in. Need to rig up new weights before the stairs go back in, but we have tornado and flash flood warnings here today so it will have to wait.

 

[PoolStored]

Nice! Congrats on the SLAM!

 

[kafox001]

Passed another OCLT with the stairs back in. I promise I will retest my CYA and confirm the level, but otherwise I think we are done here (a week and a half and a few hundred dollars in chlorine later )!

Thanks everyone for your help!

 

[PoolStored]