Puzzled by 0 CC

[setsailsoon]

Folks,

I've had a little algae accumulate on the walls and bottom of my pool from time to time and it's easily removed by scrubbing and vacuuming. The algae is off-green to light brownish in color and the layer is very thin almost translucent. This pool is only 2 years old and up 'till 2 1/2 mo ago was maintained by a pool service. They kept FC very high (over 10 ppm most of the times I checked). When I took over the CYA was less than 20. Based on a lot of helpful comments here I'm pretty sure the algae was due to lack of brushing after I took over and that sometimes my FC level got below minimum FC. The algae got more wide-spread when I left the pool unattended for 3 weeks but I had enough FC before departure that my level was 6.5 when I returned. Even though I've had some algae on the walls and floor it's never been suspended in the water. Water has always been clear. I SLAMed when I returned and it all looks great now. I get all that and it all makes sense. What doesn't add up to me is that I have never recorded any CC? None, not even slightly pink after addition of R-0003. I can only guess the algae kill CC loading must actually be very low in terms of ppm CC even though it looks like a fair amount on the wall. Since the cell contents are mostly water the actual pounds of nitrogen and other material that form CC are very low. And the actual CC is so low that the CC is oxidized very quickly because most of the time my ratio of FC to CC is actually very high. Does this make sense to the experts here or am I way out in left field or what?

The TFP method is working great for me and I plan to continue but that's partly because it makes so much sense. I like to know why it's working and not just that it does work... everything I've read and all the expert advice makes a lot of sense when I dig into the historical posts by the experts here to explain my pool's behavior. But this CC=0 is just confounding me. Any explanations to confirm my guess or offer a better explanation would be much appreciated!

Thanks in advance.

Chris

 

[duraleigh]

Combined chloramines are a transient. In a perfect pool, they will be consumed by chlorine very quickly and will often stay at zero even in the presence of algae. (As an unrelated fact, .5 ppm CC's is treated as 0 ppm for our purposes......no action needs to be taken)

During a SLAM, CC's will often test maybe around 2 ppm and then zero ppm soon after.

Do you still have visible algae on your pool walls? That MUST be brushed off into the circulating pool water where the FC will kill it. (during that time, your CC's may also go up but probably return to zero as the organics are killed off)

 

[tim5055]

In addition ot Dave's comments, being in Florida I might expect the sun to burn off the CC a little quicker than in some other areas of the country.

 

[setsailsoon]

Combined chloramines are a transient. In a perfect pool, they will be consumed by chlorine very quickly and will often stay at zero even in the presence of algae. (As an unrelated fact, .5 ppm CC's is treated as 0 ppm for our purposes......no action needs to be taken)

During a SLAM, CC's will often test maybe around 2 ppm and then zero ppm soon after.

Do you still have visible algae on your pool walls? That MUST be brushed off into the circulating pool water where the FC will kill it. (during that time, your CC's may also go up but probably return to zero as the organics are killed off)

Dave,

Thanks so much for the quick reply and that makes a lot of sense. Yes, any time I see the algae I sweep it down and I think exactly as you say it dies, clumps, and is then removed by filtration. The SLAM I just did is only the second time I've done one. Both times I pass the SLAM completion criteria next day and both times I've never had a CC above 0. Soon after the first wall scrubbing in my recent SLAM the algae was completely gone. Pool looks perfect again. I'm just amazed that in 2 1/2 months I've never recorded any CC. I do the CC every time I check FC. I think my CC load must just be very low and as you indicate it's just quickly oxidized.

Thanks again for the quick reply.

Chris