something doesn't seem right here...

[jgriff00]

Hello,

After repeated bouts with yellowish algae, I finally took the boards advice and purchased a Taylor FAS DPD kit. Spent the weekend draining and trying to establish a reasonable CYA level (was well over 100, looks to be around 60 ish now).
Chlorine numbers had been fairly predictable- I measured 20s through the day yesterday, then took it up to 28.5 last night, then it was 26 at 8 this morning. At that point, I was hoping SLAM process was complete, but I added one more 128 oz bottle of 10% bleach. This should have put my 17000g pool at around 31 or 32 ppm at that point. Then I returned home from work work today only to measure FC at 18 a few moments ago (6:30 pm).
Does this sound correct that it would maintain so well overnight only to plummet during the day? I realize since lowering the CYA, I can expect to lose Cl at an increased rate, but 15 ppm in a single day? Pool does take direct sunlight all day long, but not sure how to fight this algae at this rate of chlorine loss.

Thank you,
Jason
Spring Tx

 

[jblizzle]

Welcome to TFP!!!

The CYA level really sets the % of the FC lost to the sun. So the higher the FC level, the more ppm that will be lost to the sun. Losing 40% with a CYA of around 60ppm does not seem too unreasonable.

Did you measure the 28.5ppm and then get 26ppm in the morning? That is pretty close to passing the OCLT ... especially given the late morning test. Are your CC and water clarity good?

It kind of "seems" like you are done with SLAMing

 

[jgriff00]

Wow thanks for the quick response. Yes 28.5 was last night, then 26 this morning. CC seems to be very near zero, solution may turn a VERY light pink, but one drop clears it back every time. Water has been clear throughout, but to begin with I had yellowish algae on the shadows walls and steps. And also yellowish brown Sandy looking deposits that went away when I brushed.
So my issue is, I can take it to mustard algae shock level, but not sure how I can maintain that level through the day tomorrow.

 

[duraleigh]

What does your water look like?

What is your CC test result?

 

[jgriff00]

The water is very clear, but I am still seeing this brownish yellow stuff on the bottom in patches. Maybe it's just dead algae? CC has been zero to less than .5 the last several tests

 

[duraleigh]

Maybe it's just dead algae?

That's correct and as long as it accumulates, you have remaining organics in your pool that need to be killed by SLAM level chlorine.