what am I doing wrong (and how do I fix it)?

[CamiS]

Edited to add closure to this : thank you all for pitching in ideas. In the end I don't know what happened, probably I did many things quite fast and the water needed some time to balance. In any case, the FC loss decreased slowly slowly, I am now at 2ppm loss from one evening to the next , which I understand it's quite normal even in New England summer.
Initial post : Over the last week I drained & replaced 1/2 of our pool (to fix CYA) and I SLAM-ed it. Yesterday I had 0 CC , water has been clear throughout the process and overnight (11pm to 8am) I have lost only 0.5ppm. In the morning I had 7.6 PH, 115 Alk, 60 CH, 6 FC , 0 CC (didn't measure CYA but assuming it hasn't changed over the last 2 days, it was somewhere between 50 & 60). Tonight I had zero chlorine (0 FC, 0 CC, 0 TC...). I can add as much DPD I want, no change of color (I have both the Taylor K2006 kit - with DPD powder , and a basic Taylor DPD test with DPD liquid, both show the same , no FC ...when I add the powder or liquid, it doesn't turn pink ...). Is it possible to have lost 6ppm of FC in one day just because of the sunny day ? (today I added 16 lbs of Calcium Chloride and we heated the pool to 85 , for the first time ... not sure if it matters but just in case it does I thought to mention it...). Tonight I measured CYA and it is 50. Please advice, what is my problem and how do I fix it ?

 

[ajw22]

Add more liquid chlorine.

There have been reports over the years of 0 FC after adding calcium. No one can explain why. Just add more chlorine.

 

[Deb04]

A loss of 6 ppm in our neck of the woods with a CYA of 50 would be unusual. But, it is what it is. More chlorine. Can you test mid day to make sure FC doesn’t even approach 0?

 

[CamiS]

A loss of 6 ppm in our neck of the woods with a CYA of 50 would be unusual. But, it is what it is. More chlorine. Can you test mid day to make sure FC doesn’t even approach 0?

I will. I have no idea what is our normal FC consumption as it's our first season with this pool and since I took it over from the pool guy I've been doing stuff to it , so I had no "normal" day , with nothing done to it ... I was planning to add some more calcium tomorrow but I'll wait until I figure out this chlorine thing ... I added now 1 gallon 2 cups of liquid chlorine which according to the pool math should bring the FC to 7. I'll test tomorrow like a maniac...

 

[V___25]

A little further south but my normal is about 3-4ppm per day in peak summer. Right now I'm at about 2-3.

 

[duraleigh]

V__25's consumption is normal.....use that as a guide.

You seem to be doing a LOT of things at once - perhaps a little confusing.

Your CYA is at a good level so get FC in your pool, Calculate the dosage and then test it about 30-60 minutes later to see if your calculation was correct. Report back.

 

[CamiS]

A little further south but my normal is about 3-4ppm per day in peak summer. Right now I'm at about 2-3.

I’m in MA so sunny these days but temps rarely & for a short time exceed 80s. Overnight I lost 0.5ppm FC. Yet from 8am to noon I lost 3ppm. I seem to have some CC, under 0.5ppm (I ordered a taylor kit for low ranges so I can take more precise measurement). Pool is pristine, I just don’t understand why I’m losing so much FC during the day… (my plan is to use liquid chlorine but I was hoping to raise it every night around 6-7 and have it above 4 at all times… obviously my plan is not good … I don’t know how to chlorinate this pool properly now..)

 

[Flying Tivo]

Have you done an Overnight Chlorine Loss Test?

 

[CamiS]

A little further south but my normal is about 3-4ppm per day in peak summer. Right now I'm at about 2-3.

I’m in MA so sunny these days but temps rarely & for a short time exceed 80s. Overnight I lost 0.5ppm FC. Yet from 8am to noon I lost 3ppm. I seem to have some CC, under 0.5ppm (I ordered a taylor kit for low ranges so I can take more precise measurement). Pool is pristine, I just don’t understand why I’m losing so much FC during the day… (my plan is to use liquid chlorine but I was hoping to raise it every night around 6-7 and have it above 4 at all times… obviously my plan is not good … I don’t know how to chlorinate this pool properly now..)

Have you done an Overnight Chlorine Loss Test?

yes, two nights in a row. I didn’t wake up at sunrise (which now is around 5), measured at 10-11pm and at 8am. The first night I lost 1ppm , last night 0.5ppm, considering the few hrs of sunlight (the pool is in plain sun in the a.m) I deemed that ok….

 

[Deb04]

I think you probably have some low level algae. Water can be clear until algae really takes off. I suggest keeping your FC a little higher, say 8, until your test kit arrives. 8 is a safe swimming level with your CYA. Then do a complete set of tests with your new test kits and report back.

 

[CamiS]

I think you probably have some low level algae. Water can be clear until algae really takes off. I suggest keeping your FC a little higher, say 8, until your test kit arrives. 8 is a safe swimming level with your CYA. Then do a complete set of tests with your new test kits and report back.

I’m trying. But at 1ppm / hr loss rate, it’s a struggle… And I’m thinking algae should eat up my FC at night, too - but I lose only 0.5-1ppm from 10-11pm to 8am … This pool puzzles me …

 

[MITBeta]

You didn't have a pool party yesterday by chance? I had a bunch of people in my pool over Memorial Day weekend and was shocked (pun intended!) by how chlorine I went through in the next 2 days until it stabilized again. This was our first big "pool party" weekend since adopting TFP during Covid lock downs. Now I know better and will boost better before and after next time.

 

[CamiS]

V__25's consumption is normal.....use that as a guide.

You seem to be doing a LOT of things at once - perhaps a little confusing.

Your CYA is at a good level so get FC in your pool, Calculate the dosage and then test it about 30-60 minutes later to see if your calculation was correct. Report back.

I always add chlorine (all chemicals, actually) using the pool math app.

You didn't have a pool party yesterday by chance? I had a bunch of people in my pool over Memorial Day weekend and was shocked (pun intended!) by how chlorine I went through in the next 2 days until it stabilized again. This was our first big "pool party" weekend since adopting TFP during Covid lock downs. Now I know better and will boost better before and after next time.

Nope, nobody used the pool yet this season.... (for 1.5 mo while the pool guy was taking care of it it just looked gross and unsafe ... And I've been draining and slamming it afterwards ... ). It baffles me that there's barely any FC loss overnight - else I'd keep slamming it...

 

[SoDel]

Just taking a novice look at the data . . . your OCLT is good, your AM FC is good, your mid-day FC loss is about 3 ppm (not really crazy high) and you report CYA at 50, water is clear, CC running about 0.5 (do I have all that right?). I’d look to two places for the FC loss and see what you see. 1. retest CYA. It’s a difficult test and relies on (at least my understanding) light scattering through the melamine precipitate, so lighting makes a big difference (as does practice with the test). 2. The FC loss and continued (low) levels of CC maybe point to some organic matter in or getting into the pool. Can you think of how or why that might be happening?

The OCLT would say to me it’s not organic but maybe something in the filter or something happening during the day?

 

[CamiS]

Just taking a novice look at the data . . . your OCLT is good, your AM FC is good, your mid-day FC loss is about 3 ppm (not really crazy high) and you report CYA at 50, water is clear, CC running about 0.5 (do I have all that right?). I’d look to two places for the FC loss and see what you see. 1. retest CYA. It’s a difficult test and relies on (at least my understanding) light scattering through the melamine precipitate, so lighting makes a big difference (as does practice with the test). 2. The FC loss and continued (low) levels of CC maybe point to some organic matter in or getting into the pool. Can you think of how or why that might be happening?

The OCLT would say to me it’s not organic but maybe something in the filter or something happening during the day?

I think you might be on to something on the 2nd part… During the day we run the waterfall (I ran it round the clock while slamming the pool but it’s still a natural-ish thing, made out of rocks and things like moss & lichens grow on it - maybe not necessarily where the water runs but for certain in the neighborhood, I’ll take a more careful look at it tomorrow). And maybe I need to research the filter cleaning too (I’m taking care of the chemistry & my husband of the equipments…). Thank you, I’ve lost my minds trying to figure out a possible explanation. (I never woke up at sunrise to check over night FC loss but even at 8am it was small, 1 one night and 0.5 the 2nd… the FC consumption seem to take off once we start the pumps ; the waterfall one doesn’t go through the filter, just recirculates the water… I’ll check both tomorrow - and I’ll wake up at sunrise to get a true over night chlorine loss test… ). I tested CYA today several times - sometimes I see it 40, sometimes 50 (for sure it’s no bigger than 50 and not smaller than 40; now which of these 2, I can’t really tell… from a point on I might see things just because I know they’re there…).

 

[Deb04]

the FC consumption seem to take off once we start the pumps ;

Has the pump been running for at least 30 mins before you take the samples for evening and morning OCLT? It should be.

(I’m taking care of the chemistry & my husband of the equipments…)

Hubby and I have the same division of labor. We both think we got the good end of the deal. Same for travel. I plan EVERYTHING and he schleps the luggage.

 

[CamiS]

Has the pump been running for at least 30 mins before you take the samples for evening and morning OCLT? It should be.

I’m not sure about the 30 min in the morning, didn’t pay attention to that…

 

[Bperry]

Just in case, if you have a cover on it sometimes those can get algae on them and reintroduce it when the cover goes back on. Maybe not relevant but just in case.

 

[SoDel]

Can you not run the waterfall for a couple days and see if that changes anything?

 

[CamiS]

Can you not run the waterfall for a couple days and see if that changes anything?

That’s what I’m doing today. Meanwhile I ran a true overnight test, 0 loss sunset to sunrise (with the pump running all night - so it’s not something in the filter eating my FC …). I’ll keep measuring today with the waterfall off … But meanwhile I am thinking to let my kid swim today …(keeping chlorine in check…).