OCLT -> FC dropped but CC did too?

[jmhawkins]

Above ground Intex pool, SWG, no heater. Opened it at the end of last week. Took the cover off and the water looked good - not exactly sparkling but no tint to it. There were a lot of needles that had made their way to the bottom of the pool though (it is the Evergreen State, we're surrounded by them). I vacuumed them out, brushed down the sides/bottom, put in a new (cartridge) filter, and set about the chemistry.

TA was a little low, so I added baking soda to get it up to 70. pH was high (8.2), so muriatic acid and got it down to 7.4. FC was 5+ (OTO test, not drop), CYA was low, so added stabilizer and got it up to 60. Let the pump run. Water was sparkling and awesome looking by the weekend. But reading here, I realized I should probably do an OCLT just to be sure.

So last night I did a FAS-DPD test. I got FC = 8.0 and CC = 0.5. This morning, FC = 4.0 and CC = 0. I'm going to do a SLAM today, but was curious - I would assume if something is eating my FC that it would be creating CC. Am I misunderstanding the relationship between FC and CC?

EDIT: I should add that there's a lot of pollen in the air, and there's a steady stream of it landing on the pool surface.

Anyway, thanks, I'm still very happy with how the pool came through the winter using TFP ideas.

 

[TinFoilHat]

Because you lost 4 ppm last night with no sun on the pool then your chlorine was used up on organics in the water. SLAM on.

 

[duraleigh]

Am I misunderstanding the relationship between FC and CC?

CC's vary quite a bit when you are actively killing stuff. It may go back up some but you are understanding correctly.........stay the course!

 

[Mdragger88]

While the presence of elevated cc’s indicates a problem the absence of cc’s doesn’t mean there isn’t one.

 

[Mdragger88]

Since you have an above ground intex style pool be sure to scrub any seam flaps in the liner (some pools have larger ones than others) and check/scrub your ladder inside & out.

 

[jmhawkins]

Thanks. Just added the SLAM chlorine. And as I went out to do that, FedEx delivered my new Dolphin E10, so an exciting day!

 

[Mdragger88]

With your water being clear already hopefully your SLAM Process won’t take long but if you ever find yourself with a swampish situation it may be more reasonable to just drain & refill as those undersized thin cartridges are not conducive to filtering out large quantities of dead algae and the cost of liquid chlorine required will quickly rise higher than the cost of the water.

As for the flaps, if you have them - I found using a regular angled household poly broom worked the best. I had to finagle the flap up with my toe to get it in there but after I saw what came out I was glad I did! My water had always been beautiful and I had no clue that was lurking there but the oclt told the tale!

 

[jmhawkins]

Since you have an above ground intex style pool be sure to scrub any seam flaps in the liner (some pools have larger ones than others) and check/scrub your ladder inside & out.

Yeah, those seams... took forever with the vacuum. I'm hoping the new Dolphin will help with that (and not get stuck on them)

 

[Mdragger88]

Yeah, those seams... took forever with the vacuum. I'm hoping the new Dolphin will help with that (and not get stuck on them)

Get em good!

 

[jmhawkins]

Okay, SLAM started. CYA at 60, FC at 24.0. We'll see what the morning brings.