Here's a slightly crazy question I know...
I've been following the TFP method for about 14-15 months now - and have had zero algae in that time. All going great.
A peculiar thing I have noticed for 2 summers in a row, coming out of summer into autumn when I've used an electric heat pump to extend the swimming season, it has coincided with a rapid drop in CYA of 20 over a 72 hours or so of heat pump use where we might heat in prep for a weekend of swimming. Now I know in theory about CYA and that it shouldn't drop that quickly. And I've previously had some bad batches of CYA testing reagent but I believe this is now all resolved and I used the CCL kit here in Australia. I'm talking about a drop in CYA from 80 down to 60 in the space of a week. All tests in same lighting conditions / time of day / back to full sun / glance down waist high etc. No rain or backwashing in the week in question. (Live in Sydney - current daytime temps around 24C (75F)
I think I've read high water temps can increase the drop in CYA. The heat pump we have is the Z200 Zodiac (link - Zodiac Australia). It can get the pool water up to a max of 32C (90F) - but I would imagine the piping right within the inner element would heat the water higher than that.
In practice this has just meant I trust the test results and add CYA again to maintain a level of 80 - and all has been fine. But I still have this lingering question about rapid CYA drops occasionally.
Any thoughts?
I've been following the TFP method for about 14-15 months now - and have had zero algae in that time. All going great.
A peculiar thing I have noticed for 2 summers in a row, coming out of summer into autumn when I've used an electric heat pump to extend the swimming season, it has coincided with a rapid drop in CYA of 20 over a 72 hours or so of heat pump use where we might heat in prep for a weekend of swimming. Now I know in theory about CYA and that it shouldn't drop that quickly. And I've previously had some bad batches of CYA testing reagent but I believe this is now all resolved and I used the CCL kit here in Australia. I'm talking about a drop in CYA from 80 down to 60 in the space of a week. All tests in same lighting conditions / time of day / back to full sun / glance down waist high etc. No rain or backwashing in the week in question. (Live in Sydney - current daytime temps around 24C (75F)
I think I've read high water temps can increase the drop in CYA. The heat pump we have is the Z200 Zodiac (link - Zodiac Australia). It can get the pool water up to a max of 32C (90F) - but I would imagine the piping right within the inner element would heat the water higher than that.
In practice this has just meant I trust the test results and add CYA again to maintain a level of 80 - and all has been fine. But I still have this lingering question about rapid CYA drops occasionally.
Any thoughts?
.... have to exchange out the water to change CYA levels. Too much snow & ice. I need to be messing around with and in my pool to clear the brain cells.