Algae. Maybe.

[doc8404]

Wasn't monitoring like I did last year and like I need to be.
Came home the other day and appeared to have spots of algae or dirt all over bottom.
Water clear as could be.

I brushed it up and since it appeared to become a cloud, and my wife swearing it was greenish, I figured I would slam.

3.75 gallons of 10%.
FC 19
CC 0.0
TA and pH have been holding at 120 and 7.2-7.4
CYA 35-40

next/this morning: 18.5 and 0.0
left the solar cover off so it would burn some off.
Brushed the entire pool including the bottom.
Today's air temp was 90 degrees and water hit 82.

Testing now at 9:15pm
FC 5.5
CC 1.0

anything else I need to do?
appeared OCLT was good to go.

Did i really burn that much FC just with the sun and a brief swim?
Or do I have something going on?
if so, monitor or SLAM again?

 

[jblizzle]

Did you pee in it?

That drop is possible. I would just monitor your FC usage over a couple days.

 

[doc8404]

We did swim in the lake today and then straight in the pool 2 hours before testing. Not something we usually do.

Thanks. I will tell my wife you agree with me so she can go to bed

 

[jblizzle]

Lake to pool is certain to introduce organics to the pool and cause FC losses. Can introduce the dreaded yellow algae too.

 

[doc8404]

I feel I was very accurate in last night and testing this morning. Can you have the free chlorine stay the same but combined chloramines drop?

Will certainly keep a very close eye on it. I tested again this morning. Is this even possible?

FC 5.5
CC 0.0

 

[jblizzle]

Yes it is possible. Agreed, keep an eye on it, but nothing seems amiss.

 

[doc8404]

Looks like the rain dropped my CYA to less than 20.
Guess that's why that one sunny day and 2-3 days of not testing or treating let that algae grow.

We must've caught it just in time because we had no issues after one overnight slam. I have bags of Dichlor and tabs of TriChlor. Time to throw a pound of Dichlor shock in each day for the next 4 to 6 days to bring the CYA up.

 

[doc8404]

I guess it could also be the new reagent I received today.
Sucks I ran out!

 

[doc8404]

There is no way a couple inches of rain and sun drop my CYA in half. Is there?

 

[mknauss]

Depends on how long between tests. CYA naturally breaks down about 3-5 ppm per month, maybe a bit more in intense sun. The testing procedure must be the same with the same ambient conditions. Even then, the testing has a variable of +/- 10 ppm.

Take care.

 

[doc8404]

Thanks.
The bags of dichlor (bioguard smart shock) are coming in handy.
Appears 1# raises my FC 2.5.

And last CYA test was a different bottle of reagent but more importantly as you pointed out, about a 20° difference in water temperature.