Large Drop in CYA over Winter

[briansturgeon]

I just popped a couple of straps loose to get a water sample since I will be pulling cover off tomorrow (mesh cover). I tested my water and got the following: FC = 0 of course; CYA - I filled all way up and still saw dot so I have to estimate between 5-10; TA = 60; PH = 7.5

Weird thing is that I'm pretty sure when we closed pool CYA was around 30ish. Water temp of sample is about 70 F.

Also, at the end of last year I believe I was fighting MA. Therefore, I stocked up on the Menards bleach sale today only to come home and find out I have such a low CYA I can't read it. I guess I will have plenty of bleach since it won't take me nearly as much as I was thinking.

My question is is it normal to lose CYA over the winter in a seasonal pool?

Also, my understanding to kill MA is to follow normal shock process until passing the overnight test and then bring to MA level. How long do I maintain MA level? One more question. If I don't actual see any MA when I pull the cover and look around does it mean I don't have any or can it just go dormant and wait to grow?

Thanks

 

[257WbyMag]

CYA can be lost over the winter due to a process that has been known to occur when the FC drops to zero. See this link for a detailed explanation but basically, it isn't as uncommon as we once thought.

degradation-of-cyanuric-acid-cya-t8880.html

 

[frustratedpoolmom]

Also, my understanding to kill MA is to follow normal shock process until passing the overnight test and then bring to MA level. How long do I maintain MA level? One more question. If I don't actual see any MA when I pull the cover and look around does it mean I don't have any or can it just go dormant and wait to grow?

We like the water to circulate for several hours before we test... your numbers may change - just an FYI.

IF you proceed with MA level shock, 24-48 hours should suffice. If you don't see what you suspect was MA, I would wait until you do before you bother.

 

[NWCanuck]

I was between 30-35 CYA last year when closing and also opened this year to unreadable CYA levels. I have since added almost 2 Kg of CYA since opening last weekend and I am just now reaching 30ppm. Then again here in Ontario I drain below the returns and refill with clean unstabilized water every spring. So no surprise for me.