Questions about lowering my CYA

[CraigChing]

To make a long story short, pool maintained by previous owner using dichlor/trichlor and having learned about the FC/CYA relationship late last year, I started using liquid chlorine and TFP methods (for the most part) this year. I had an extremely high CYA, probably > 300 at the end of last year. Since opening and having done a couple of test partial drains, I've got my CYA to 160, a measurement I'm confident in.

I really want to get my CYA to a better range and have read the Draining article, but have some questions.

First, my numbers (all in pool math as well):

FC: 9
CC: 0
pH: 7.4
TA: 140
CH: 200
CYA: 160
Temp: 85

My fill water looks like this:

TA: 350
pH: 7.2
CH: 250
Temp: 65F

I know I'm not maintaining minium FC for my CYA, but I've been watching my water very carefully all year and where I'm keeping my FC levels now has afforded me a cheaper chlorine bill and a sparkling, clear pool so far. I understand the potential consequences and this post is not about that, but how to get my CYA manageable so I can maintain the correct FC levels.

So, my questions:

1. My fill water TA seems super high and when I did the partial drains earlier this season (in May), my TA went up and I've had to do serious pH adjustments since. Are there any concerns about TA with my fill water?

2. I want to try the "No Drain Water Exchange" since I really don't want to mess with my liner. With my fill water at 65F and my pool water kept at 84F, do I want to drain from the shallow end and fill from the deep (about 8' deep end)? I am going to buy a 1/2 HP sump pump like others have posted here for this part.

3. If I do fill in the deep end, do I shove the hose down into the deep end? If so, are there any precations I need to consider?

I may have more questions as I think through this, but I appreciate any help!

 

[mknauss]

TA is the parameter to be least concerned about. So deal with it as necessary after the exchange.

That is a significant water temperature difference. So yes, add to the deep end and pull from the surface.
Just be sure the flow of water from the hose is dispersed some. For instance, you do not want it pointed towards the surface at full force. Putting some holes in a plastic bottle and securing it over the end of the hose will work to disperse the energy of the water coming from the hose. Or any other method you can devise.

 

[CraigChing]

Thanks @mknauss ! So your bottle method, keep hose and bottle above water and the water temp will make the water sink? Any other concerns other than what’s in the article?

 

[mknauss]

No. The hose end must be on the bottom of the pool. Be sure it is secure at the deepest part of the pool.

 

[CraigChing]

Got it, thanks!