SWG output question

[AZRider]

I have been running my IC40 at 10% 21 hrs. a day for the last month and have consistently been getting readings from 4.0-5.0ppm never below 3.5. This week I got a reading of 2.5ppm waited tested again next morning still 2.5ppm.
No CC on any of the tests. I increased it to 20% output 21/hrs. a day. Now pool is 4.0-5.0ppm again. What would cause it to change output by half? Water temps are dropping now highs were 90 now peaking at 85. pH was high the last few days since I was out of acid. Seems odd to me that I would have to double output to get same result I was getting for weeks previously. Any ideas?

 

[mknauss]

CYA?

 

[AZRider]

CYA has been 60 last 2 tests

 

[mknauss]

Have you tested CYA since the increase in FC demand?

 

[Newdude]

Are you using a cover ? 1.6 ppm (10% production for 21 hours) loss is almost unheard of in the desert. 20% / 3.2 ppm added per day is still arguably low loss.

 

[AZRider]

No I assumed it would not change much without a drain and fill

 

[mknauss]

Are you using a cover ? 1.6 ppm (10% production for 21 hours) loss is almost unheard of in the desert. 20% / 3.2 ppm added per day is still arguably low loss.

Good point. Mine runs at 5 ppm give or take.

 

[mknauss]

No I assumed it would not change much without a drain and fill

You will lose 15% plus per month during our summer months.

 

[AZRider]

Are you using a cover ? 1.6 ppm (10% production for 21 hours) loss is almost unheard of in the desert. 20% / 3.2 ppm added per day is still arguably low loss.

no cover

 

[AZRider]

I will test CYA again to see if it changed

 

[proavia]

Dose FC to high end of target range using liquid chlorine.

Retest CYA - it will degrade some, especially in hotter temps.
Dose CYA to attain a reading of 70.

If still losing more than expected, do an Overnight Chlorine Loss Test (with SWG off or set to 0%).

 

[Newdude]

Then you can expect to lose up to 5ppm per day as Marty said. Plan for that and if you consistently lose less, don't look a low loss pool in the mouth. But still cover your rear.

I found my cell off the other day for low salt (it wasn't) and we had blue skies with no rain for a week. I've also found it off after big rains (not applicable for you), or simple system glitches / power outages. Running a 4 to 5 FC is one hiccup away from swamptown. On any given day a hiccup is unlikely, but with 275 chances in your loooooooong season, it's gonna happen, maybe a few times.

I have much friendlier UV than you and run 8 to 12, adjusting the cell if I catch it drifting one way or the other. When it shut off all day, I dropped to 11 and was still well covered.

*note.

Running hot is not a need, it's a choice. But the closer you dance with minimum, the closer you need to pay attention if it dips.

 

[AZRider]

Just tested CYA again. It is looking like 80 now But we have overcast skies this morning so not 100% sure on the number

 

[proavia]

Just tested CYA again. It is looking like 80 now But we have overcast skies this morning so not 100% sure on the number

So for right now, go with CYA 80 and dose FC to high side of target range using liquid chlorine to get to that goal quickly. Monitor FC daily and adjust SWG percentage as necessary to stay on high side of target range. After a week or so, you will get a better feel for what your pool needs. Then go back to checking FC every few days.No need to micro-mange it, close it close enough.

If you test CYA again once the sun comes out, adjist your target accordingly.

FC demand will drop as our temps cool - you know, around mid October thru late January.

 

[AZRider]

So for right now, go with CYA 80 and dose FC to high side of target range using liquid chlorine to get to that goal quickly. Monitor FC daily and adjust SWG percentage as necessary to stay on high side of target range. After a week or so, you will get a better feel for what your pool needs. Then go back to checking FC every few days.No need to micro-mange it, close it close enough.

If you test CYA again once the sun comes out, adjist your target accordingly.

FC demand will drop as our temps cool - you know, around mid October thru late January.

Thanks, I dosed it with Liquid Chlorine to max target. I will watch it for now. Maybe the IC40 starts with higher output initially and drops once it breaks in. I was worried something was wrong when output dropped in half

 

[proavia]

Post a full set of current test results.

FC
CC
pH
TA
CH
CYA
Salt
Water temp

Use PoolMath and track CSI, water temp and CC.
Keep CSI in the 0.00 to -0.30 (negative 0.30) range to minimize SWG scaling.

You can also link PoolMath to your forum account so we can see your test results by clicking on your member icon and PoolMath Logs.

 

[Newdude]

I was worried something was wrong when output dropped in half

The output stayed the same. The UV loss increased whether the CYA dipped or the clouds parted.

 

[mknauss]

Just tested CYA again. It is looking like 80 now But we have overcast skies this morning so not 100% sure on the number

How did it go up from 60 to 80? Have you been adding CYA or CYA containing products?

 

[AZRider]

How did it go up from 60 to 80? Have you been adding CYA or CYA containing products?

Nothing has been added, I assume overcast conditions are affecting the reading. I will test again when we have bright sunshine again.