Hi there -- We've owned a 30,000 gal SWG in-ground pool for about a year now and through a combination of a bad wind and stupidity (mine) now have what is probably mustard algae growing on the walls (the water is clear). ::sigh:: I thought we were draining the pool this winter so I didn't stay totally on top of things -- and then the hubby didn't get the drain & refill set up in time. Pool lesson 1: Stay on top of things. Pool lesson 2: The husband is no longer a decision-maker re: the pool. Pool lesson 3: STAY ON TOP OF THINGS. So, I'm now mired deep in regret, doing pool penance, and getting ready to SLAM the **** out of it starting this weekend.
Anyway, I've read through the forum this past year and have been testing my own water all along with the Taylor K-2006 kit and I have enough recurring issues with the CYA test that I don't trust myself or my readings. I find that test very subjective and hard to read. Am I imagining the black dot....is that a hint of a black dot....wait, is the black dot gone....no, wait, it MIGHT still be there.... You get the picture. On the whole, my CYA was around 60 all last summer and fall -- the consistency of my readings reassured me. Once this winter, I got a reading of 80, then a few weeks later I got 40. Then back to 60. And now I got 40 yesterday and wondered if I messed up, so did it again today and got about 35. We haven't been in the pool (no splashout) and have not drained any significant water. 35-40 seems too low and I don't want to add stabilizer and then get high readings and have to drain water, etc.
With the impending SLAM, I need to have a good read on the CYA to find my FC target for my regular SLAM and then Mustard SLAM.
FC: 6 (I've been keeping this on the higher end of normal while waiting to SLAM)
CC: 0 to 0.5
TA: 100 (I'm currently bringing this down -- it was 150 two days ago and I've been adding acid and aerating -- heading to 70 if I can get it there)
CYA: Who the **** knows. Maybe 35. Maybe 40. Maybe more? But why isn't it still 60? Should the fact that I don't UNDERSTAND the reading CHANGE the reading? LOL
So now to the questions:
What causes CYA to drop over time? I keep hearing only draining and splashout, but we've done neither and my CYA readings are way down.
Would you just proceed to SLAM assuming a CYA of 40 and then test again for CYA after the SLAM is done and adjust if it still reads low?
Why, pool universe, do I have so much trouble reading/trusting this CYA test? Is there a better one than what I've got?
And, from the husband: Can we REALLY pull out the pool light to brush for mustard algae without electrocuting ourselves?
Thanks everyone for being here -- this forum and the Pool School have been so helpful -- though I swear I'm only now feeling like I'm getting a handle on the whole pool thing.