Help please! FC/CC test!

[JimMarshall]

Can not having enough FAS-DPD powder in your sample to start out with cause a low FC (I know this answer to be yes) and a high CC reading?

Just tested and came up with FC 4.5
CC 2.5
CYA is around 30-40 but I haven’t had a good sunlight day to verify since I last added. Based off the last couple days readings, additions, and the looks of my pool, this made no sense to me unless there is a dead animal under my solar cover that I’m unaware of.

Decided to test again to verify, used 1.5 scoops of powder, got FC 8.5, CC .5

 

[Texas Splash]

Too much doesn't hurt and is just a waste. Too little can influence the test. If you are using the 10 ML water sample, one scoop should be enough. I always use one heaping/rounded scoop (not flat/level) and my FC testing is always very consistent. Also remember that while the cover is great to save FC from the sun an help keep debris out of the pool, it can influence oxidation by blocking the sun and at times your CC may increase because it has nowhere to go.

 

[JimMarshall]

Update: I ran an OCLT and my tests matched from last night to this morning, FC 8.5, CC .5. I guess we can attribute the first instance to some sort of weird testing error. Just goes to show that even after a couple years of being used to the tests no one is perfect and everyone can make mistakes. My scoop I think got wet and has a bunch of DPD powder caked on it, wondering if that contributed by decreasing the amount of powder I’m getting per scoop

 

[Texas Splash]

My scoop I think got wet and has a bunch of DPD powder caked on it, wondering if that contributed by decreasing the amount of powder I’m getting per scoop

Mine does that too. I clean it periodically to get that old junk out.