Newbie - Stubborn CYA Levels!

[jec199]

Hi All - New to forum but learned a lot just reading. Am trying SO hard to get reasonable CYA levels so I can SLAM and convert to borates. Before reading TFP website I choked my pool with 3" chlorine tabs to "eliminate algae." Of course result was CYA levels thru the roof! And chlorine low. Am now using bleach. But I can't get CYA levels below 89. Have pumped water out while filling water - simultaneously. Using 1,600 gophers pump. Started 2 hours at a time and even 3 hrs at a time. I turned water over at least 1.5 times (12,000 gal fiberglass pool). What the heck am I. Doing wrong?

Thanks!

 

[chiefwej]

If you remove and add at the same time it will take a very long time. Better to drain 60% of the water, then when you refill the CYA will be 35. If you do a series of drain and refill or simultaneous draining and filling, a substantial portion or the water you are draining is fresh water you just put in, that's why it takes so long and wastes so much water.

 

[jec199]

CYA down to 69 today. How much of 12K pool should I drain - at once - before I add fresh water. Gosh , wish I would've written in sooner! A million thanks!

 

[kj5kb]

69 is high, but manageable in my opinion...you'll just have to keep your FC at a higher level. Simple math...1/8 drain of the pool would remove 1/8 of the CYA: 69 x 7/8 = 60.