Large FC loss...stumped.

[PoolStored]

I check FC daily and adjust SWCG. I don't always log FC and SWCG adjustment. FC is always between 7-11. SWG 10-20%.

FC 36 hours ago was 9. Test this morning and FC = 5.5.

We had rain last night, but about .1 inches. So I thought I got some stratified rain water in my sample even though I took sample 18" down. So I brushed a bunch and turned on robot. Retested the same.

I clean my kit religiously. My reagents are new. My sample volumes are correct. The SWCG shows no error and makes chlorine.

The only other thing I can think of is that the salt level is 2800. Maybe there is some magical point where the SWCG is happy showing 3200 for salt level, but with only 2800 actual it is not as efficient. I can't believe that is the case as I haven't added water for a while and have a cover. Doesn't make sense to have a 4ppm FC drop in 36 hours because of lower salt.

I'm stumped.

 

[Texas Splash]

When I went through this last season I did the following pretty-much in this order:
1 - OCLT
2 - Validated CYA & salt
3 - Cleaned cell
4 - I attempted an overnight FC gain test, but that's really difficult.
5 - Added a dose of PR. That finally gave my cell new life.

 

[DrewLG]

We had rain last night, but about .1 inches.
....
The only other thing I can think of is that the salt level is 2800.

How often do SWCGs test the pool's salt level? If yours was fooled by the rain and measured low salt, would it have stopped generating chlorine until the next test?

 

[PoolStored]

When I went through this last season I did the following pretty-much in this order:
1 - OCLT

I'll do this tonight.

2 - Validated CYA & salt

Tested and cleaned three times, all the same, 70 and 2800. Added salt to get back to Circupool recommended levels.

3 - Cleaned cell

With my negative CSI, my cell is clean as a whistle.

4 - I attempted an overnight FC gain test, but that's really difficult.

I've tried this twice with little success. I've turned it up to 100% for 6 hours and will see where we get by this evening. If necessary, I'll add LC.

5 - Added a dose of PR. That finally gave my cell new life.

What is PR?

 

[Texas Splash]

What is PR?

Shhhhhhhhh. No one is supposed to know. P-Remover.

 

[PoolStored]

How often do SWCGs test the pool's salt level? If yours was fooled by the rain and measured low salt, would it have stopped generating chlorine until the next test?

Mine just turns off. The only time it happened is when I put a hose to fill near a skimmer. I had to reset the unit.

 

[PoolStored]

Shhhhhhhhh. No one is supposed to know. P-Remover.

I figured it out about 1/2 nano-second after I hit enter. Phosphates are 700.

 

[reggiehammond]

How are you testing? Are you using a recommended test kit? Test Kits Compared

 

[Flying Tivo]

When that happens to me i usually blame it on the power going out for few hours.

 

[PoolStored]

Maybe I hit some odd/mythical salt threshold for this cell and it stopped producing. My FC demand is about 2-2.5ppm daily (solar cover) and is really consistent. The only thing I can conger up is that I hit some threshold of efficiency and production fell off a cliff. Doesn't make sense that it is a cliff and not a gradual reduction...

RJ-60 Manual:

 

[Getitrite]

Maybe I hit some odd/mythical salt threshold for this cell and it stopped producing. My FC demand is about 2-2.5ppm daily (solar cover) and is really consistent. The only thing I can conger up is that I hit some threshold of efficiency and production fell off a cliff. Doesn't make sense that it is a cliff and not a gradual reduction...

RJ-60 Manual:
View attachment 521198

I recently increased my salt level, after reviewing the manual, prompted by some other posts about ideal salt levels.

 

[duraleigh]

FC 36 hours ago was 9. Test this morning and FC = 5.5.

I don't get it......................4.5 loss of FC in 36 hours with this heat seems perfectly normal to me. Admittedly, I did not read this whole thread but help me understand what is abnormal about it?

 

[Newdude]

help me understand what is abnormal about it?

There's a beast of a SWG that should be maintaining the preferred daily target with only minor fluctuations.

 

[PoolStored]

I don't get it......................4.5 loss of FC in 36 hours with this heat seems perfectly normal to me. Admittedly, I did not read this whole thread but help me understand what is abnormal about it?

My pool has been on 24x7 SWCG at 10-20% and maintaining my FC between 7-11 last year and this year. SWCG stayed on last 36 hours at 20%.

FC dropped 4ppm in those 36 hours.

I haven't seen more than a 1ppm drop in 48 hours with the SWCG on...like ever...and that is when I was high (11) and turned down SWCG to 10% and it took 2 days to drop 1ppm

 

[duraleigh]

Oops I missed the SWG altogether. That said, I am not sure one can expect very level chlorine demand to the extent poolstored is.

I already know his (and all of us) weather conditions (HOT< HOT< HOT) and I just don't think our pools will behave in this burst of heat as they would otherwise. It certainly is a variation from normal (but not ALL that much) and will end up as "one of those things"

Tivo's "power outage" is a good theory but I doubt that, again because of the heat, that loss would go undetected.

 

[PoolStored]

Temps haven't been all that bad. The 9FC test day high was 78, yesterday 83...but there were hotter days earlier. Personal weather station report:

 

[PoolStored]

Week before was consistent with this week.

 

[PoolStored]

106 oz of probably 8% liquid chlorine remaining in the stenner for about 2.4 FC, and 100% output on the RJ-60 for 6 hours, or 3.2FC. FC back to 10.

SWCG now takes 35% to maintain 10 all day, instead of 10-15%. The only thing I can think of is that I ran too long with salt at 2800-3000 and the longevity of the cell is affected. I would expect that to be in duration longevity, not output of the cell, but maybe the output of the cell has changed. Just surprised that it happened so fast.

Or, there was something in the rain, which I doubt.

Will do OCLT when I get back from vacation and see if there is algae. Turning SWCG up and it should maintain 10+.

Still stumped.

 

[Newdude]

Or, there was something in the rain, which I doubt.

What if it was more about the timing with the units self check than the content of the rain. You said it wasn't much rain but it doesn't take much to dilute the top water enough to trip the low salt warning. Or it only had to rain heavy for 25 seconds to make you drop 12 hours of production.

 

[PoolStored]

The rain was at 2am before I tested at 8am. At night, the SWCG off for 6 hours, shouldn't cause a drop of 4FC.

Also the SWCG didn't trip, it was on and producing.

I have had LOTS harder rain and it has never tripped, except when I had the hose and added about 500 gallons, right next to the skimmer.