Draining help to get rid of cya

[Erdo]

Hello all! My cya is around 160-180 with dilution testing method and I need to drain about 70-75% of my water. I want to do this drain in 3, 25% drain increments due to me having a vinyl liner. I don't have a submersible pump but I do have the multiport valve. What is the best way to drain 25%? Should I close off the deep end skimmer and the main drain or one of them? And what about the shallow skimmer? Is it possible to close the deep and shallow skimmer at the same time? I can then set the multiport to waste correct? I'm confused and am wondering what my best approach would be without the submersible pump. I have attached a picture of my skimmer and main drain lines.


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[Richard320]

With your setup, I'd just set it to draw 100% from the main drain. then there's no worry about getting distracted and having it suck air and lose prime and smoke your pump.

 

[Erdo]

Ok thanks Richard. So I can just turn the deep and shallow skimmers off with the black handle?

 

[Casey]

Make sure you leave a ft of water in the shallow end so your liner doesn't float up causing wrinkles.

 

[jblizzle]

What is your target CYA level? Three 25% drains do not equal one 75% drain.

Assuming 170ppm to start, a 75% drain would take you to 42.5ppm
using 25% drains would give you: 170*.75 = 128ppm ... * .75 = 96ppm ... * .75 = 72ppm ... * .75 = 54ppm ... * .75 = 40ppm

So it will take five 25% drains to get to the same ppm as a single 75% drain.

 

[Erdo]

Ok thanks jblizzle.