Back from vacation some strange issues

[Titan7]

So just got back from Hawaii for 10 days when out to check the pool. Notice some very light green algae formed in a corner that does not get the best water flow, also noticed a dark black spot on my Baja shelf, though it was a leaf, nope, had to brush it off and there is now a very slight outline, I was thinking black algae? It was the size of a 50cent piece. Then I though ducks or bird dropping? I have caught a duck in the pool a couple times in the past month.

So I decide to check out the chems:
FC- 6.5
CC- .5 to 0 ( I did this test twice, if there is any pink it’s REALLY faint)
PH-7.8. (Added 20oz of acid to lower ph to 7.2)
Cya- 40-50 I hate this test, and yeah I know I need to get that to 60-70.
CH-475
TA-70
Csi- -0.03

I just tested FC at dust at 6.5ppm will do overnight test and check the FC in th morning.

I am assuming I will need to shock as something is in there? But why the almost non-existent CC result?

Thx

 

[splashpad]

So just got back from Hawaii for 10 days when out to check the pool. Notice some very light green algae formed in a corner that does not get the best water flow, also noticed a dark black spot on my Baja shelf, though it was a leaf, nope, had to brush it off and there is now a very slight outline, I was thinking black algae? It was the size of a 50cent piece. Then I though ducks or bird dropping? I have caught a duck in the pool a couple times in the past month.

So I decide to check out the chems:
FC- 6.5
CC- .5 to 0 ( I did this test twice, if there is any pink it’s REALLY faint)
PH-7.8. (Added 20oz of acid to lower ph to 7.2)
Cya- 40-50 I hate this test, and yeah I know I need to get that to 60-70.
CH-475
TA-70
Csi- -0.03

I just tested FC at dust at 6.5ppm will do overnight test and check the FC in th morning.

I am assuming I will need to shock as something is in there? But why the almost non-existent CC result?

Thx

My guess is you had a good FC level when you left, so it's kept it at bay, I would try raising the FC to shock value for CYA/50 overnight and see what the FC is in the morning Hopefully you caught it and are good to go!

 

[mknauss]

CC's are burned off by the sun. So not unusual to have minimal CC after a full day of sun.

You need to follow a SLAM Process. We do not shock. We SLAM.

Do not raise your CYA until you have passed the three criteria for a successful SLAM. You can turn off your SWCG during the SLAM too.

Take care.

 

[splashpad]

My guess is you had a good FC level when you left, so it's kept it at bay, I would try raising the FC to shock value for CYA/50 overnight and see what the FC is in the morning Hopefully you caught it and are good to go!

I should have been specific, in that I was suggesting an Overnight Chlorine Loss Test, to see if a SLAM Process was in order. My apologies.

 

[Titan7]

Been keeping the FC @ 16 ppm or higher, brushing. Crystal clear water, 0 CC. The last OCLT had a 2 ppm FC drop, that was from 19ppm to 17ppm. So I kept on it today bump up FC to 19 ppm at 8pm, tonight, will test again at 6am. Question, with FC so high am I still looking for a 1 ppm or less drop in FC by morning? Also is there a amount of time for the OCLT or just dusk to dawn, 8pm to 6 am.

 

[mknauss]

At that level of FC you should be able to test with accuracy a 1 ppm drop over night.
If you have successive nights of not meeting that but still have less than 0.5 CC in the AM and crystal clear water, we can discuss letting the FC drop some for the OCLT.

The OCLT must be from right after dark to before sunrise. Preferably at least 8 hours.

 

[Titan7]

Just a follow up, all good, passed OCLT, 0 CC, clear water. All good, I am waiting for the FC to drift back down from 20ppm. I added liquid CYA, I need to really get it to 60-70ppm, I got lazy and let it sit from 40-50ppm. Also I think I am going to run my FC a bit higher than 5ppm, I am going to shoot for 7ppm. I believe running @5ppm was allowing my FC to drop into the danger zone at times and possibly allowed algae to start.