CYA, SLAMming, it never ends...

PoolEric

Bronze Supporter
Jun 21, 2018
18
Arlington, MA
Howdy all... I continue to be thankful for the existence of these forums. I'd probably be swimming in algae with out it!

So, the current conundrum...

My CYA was around 80 or 90 (depending how much I squinted), so I tried to keep my FC around 9 or 10. I'm using liquid chlorine allegedly at 12.5%, but according to PoolMath the attained levels weren't what they ought to be, so I'm assuming it's more like 10%. I've had a solar cover on the pool, and the water temperature is around 80ºF.

Issue is that I'm losing chlorine like... well... a lot. FC would go from 10 to 4 overnight. So I figured I'd need to do the SLAMming thing (which is all the rage these days). The water is crystal clear (yes, I know, that doesn't mean clean)

The SLAM FC for CYA around 80-90 is 31-35. I've cranked my FC up to those levels for two nights, but they drop a lot the next day. Disclaimer: I can't catch the FC before/at dawn because I'm still sound asleep at that hour. But the FC still seems to much. Today it was 20, after being at SLAM levels last night (solar cover still in play). The CC is zero.

I had already brushed all the algae I could find after the pool was opened, and tossed in some poly algeacide for good measure. At the current CYA level, and with the solar cover, I can only think there's something in there that is eating up the chlorine (or vice versa). SLAMming at this CYA level is gobbling up a LOT of chlorine == $$ :(

For the **** of it, I double-checked the CYA today. It showed as 50ppm. I triple checked it. But... but... CYA is supposed to be forever (kind of like diamonds). In fact I spent a month a few years ago swapping out water to reduce it.

So now, with CYA 50 the FC is 20, which happens to be the SLAMming level. But I'm uncertain what to do.

Just from the numbers, I guessed I'd leave everything and see what happens tomorrow. But the sudden drop in CYA just makes me wonder if I'm missing something (I usually am). And how often is "typical" for the number of SLAMs that need to be done before everything is dead, dead, dead! Yeah, I know, there's probably no answer to that, but I thought I'd ask.

Thanks in advance, oh wise ones! :lovetfp:
 

PoolEric

Bronze Supporter
Jun 21, 2018
18
Arlington, MA
The SLAM Process requires POP. Pool Owner Patience. It can take 1 to 4 weeks or more depending on the amount of algae and how often you can bring the FC back to SLAM level.

CYA does degrade over time. Read CYA - Further Reading
Patience...??? Who has time for patience???? :ROFLMAO:

I'd read that article on CYA (and every other one I could find). They describe losing CYA over the course of months, while mine is within a week, plus my pool water isn't quite 90ºF... last I checked it was 80ºF

We'll see what happens today.

Thanks! :drown:
 

PoolEric

Bronze Supporter
Jun 21, 2018
18
Arlington, MA
I assume you're doing all the recommended things: shaking it, waiting 30 seconds, shaking again, putting your back to the sun, holding at waist level, just glancing, not staring, at the tube?
Sure am! Over the past several weeks the CYA seems to have stabilized (pun intended) at 50.
 

PoolEric

Bronze Supporter
Jun 21, 2018
18
Arlington, MA
And since we're back in this thread... I am using 1 gal of 12.5% chlorine/day, due to roughly a 5ppm loss of FC over 24 hours. CYA is 50. It's been very sunny lately.

Is 5ppm excessive? Do I need to SLAM again?

Continued thanks to all...