Numbers look good - why Algae?

[ddurrett896]

Salt Pool with the numbers below. See a little green in the same spots everyday and brush, but it returns the next day. When I brush the liner walls/floor, I see a cloud of what looks like algae disperse. What gives? Thanks!

CYA: 50
FC: 6.5
PH: 7.6
TA: 60

 

[dBsooner]

Could it be pollen? Perform an OCLT: Overnight Chlorine Loss Test

You're also a little low on CYA for an SWG. 60 is the recommended lowest level. ANd if you don't have an SWG, you're at the bottom end of recommended FC. I'd shoot for 8.

 

[newdude]

How often are you testing ?

What time of day are you testing ?

What's the run time in relation to the daily UV loss ?


If you only ran the SWG at night for example, and tested 6.5 in the morning, you could easily be below minimum at the end of the day. Then the SWG adds 4(?) overnight and it looks great the next morning.

 

[Jimrahbe]

896,

If you keep your FC and CYA in the proper relationship, you will not get algae. So, either you had algae before you got your latest numbers in balance, or you let it drop at some point. If you did an initial SLAM, there still could be some hidden algae, in the light or under a ladder etc.

The Target FC will not kill algae. Once you see it, you should immediately perfrom a SLAM. The sooner you do a SLAM, the less time it will take.

If you are not sure it is algae, then you should do an OCLT, first.

Thanks,

Jim R.

 

[ddurrett896]

How often are you testing ?

What time of day are you testing ?

What's the run time in relation to the daily UV loss ?


If you only ran the SWG at night for example, and tested 6.5 in the morning, you could easily be below minimum at the end of the day. Then the SWG adds 4(?) overnight and it looks great the next morning.

Test FC/PH/TA once a week, CYA once a month.

Test is always done during the day, normally middle of the day. I run my pump 8am-4pm and this test was done at 3pm, so should be a pretty accurate read.

 

[newdude]

Test is always done during the day, normally middle of the day. I run my pump 8am-4pm and this test was done at 3pm, so should be a pretty accurate read.

Ok GREAT. You'd be surprised how easy it is to be fooled into thinking everything is fine.

Test FC/PH/TA once a week,

Alot can happen over the week. I stumbled upon a hiccup by accident. I drained too much and with a big storm coming, I shut the pool off to let Mother Nature fix my goof. Once full again, when I fired up the pump, mostly rain water cycled first and the cell through a low salt warning. Had I not caught it, the cell would have stayed off until it's next 12 hour self check. An overnight storm may have done similar to you, leaving no FC production for the day.

Maybe some days mid week had high UV loss, but the day before you tested was cloudy so everything looked OK in the end.

However it happened, you dipped below minimum FC and the cure is to adjust the target higher for more wiggle room going forward.

You can also raise the CYA to 70 and road test if it holds FC better by testing a couple times throughout the day once it's registering as 70.

 

[ddurrett896]

Ok GREAT. You'd be surprised how easy it is to be fooled into thinking everything is fine.

Alot can happen over the week. I stumbled upon a hiccup by accident. I drained too much and with a big storm coming, I shut the pool off to let Mother Nature fix my goof. Once full again, when I fired up the pump, mostly rain water cycled first and the cell through a low salt warning. Had I not caught it, the cell would have stayed off until it's next 12 hour self check. An overnight storm may have done similar to you, leaving no FC production for the day.

Maybe one day mid week had exceptionally high UV loss.

However it happened, you dipped below minimum FC and the cure is to adjust the target higher for more wiggle room going forward.

You can also raise the CYA to 70 and road test if it holds FC better by testing a couple times throughout the day once it's registering as 70.

Appreciate the info! One other thing...

Back in April we were getting ready to leave for a week long trip over spring break and I was doing my final check over everything. Noticed a little green in one corner and freaked out knowing I couldn't SLAM because I'd be gone and we were leaving in like 2 hours.

Threw 4 gallons of LC in there, left the pump running while we were gone and came home to a beautiful pool and it's been perfect for the last 2 months. Is there a chance something was still hanging around?

 

[newdude]

Is there a chance something was still hanging around?

Always, if it wasn't properly addressed. Or it's a second issue.

You can skip the Overnight Chlorine Loss Test with visible algae and go straight to SLAM Process.

Pay close attention at first to ensure you have more wiggle room going forward. I would also want more CYA for the heat that's sure to come real soon in VA. But don't raise the CYA until the SLAM passes all 3 exit criteria.