Potential partial drain and double checking steps using vacuum port

[ankur496]

Hi all,

I have a 30K IG Plaster/Concrete saltwater pool in Southern California. I've attached some photos of my equipment. I'd like to partially drain my pool because
(1) My calcium levels are very high
(2) My CYA levels are starting to creep up and
(3) I'm beginning to see mustard algae and want to shock the pool (so would like to lower the CYA first to make it more feasible)

I cleaned the filter grids (for the first time, painstakingly) yesterday and re-added DE after.
Leading to the pump, I have two lines: (1) skimmer and (2) suction hose

Here are my levels as of yesterday using my K2006 kit (and the phosphate reading from Leslie's for what it's worth):
FC: 7.6ppm
CC: 0
TC: 7.6ppm
pH: 7.7
TA: 85
Salt: 3400 ppm
CYA: 100
Calcium Hardness: 950ppm
Phosphates: 490 ppb

I have a few questions:

1. When I run the backwash, it runs to a sewer drain but overflows a bit (see photo). Is this an issue? I have a link to a video of what it looks like here.
2. Is it reasonable to drain the pool to lower the CYA to make the high FC SLAM levels more attainable for eliminating mustard algae?
3. Can I drain the pool by (1) setting my valve completely to the vacuum port, (2) opening the backwash, and (3) turning on the pump so that the vacuum sucks out all the water? Or is there a more straightforward way?
4. How do I calculate how much of the pool to drain to get my Calcium levels down to a reasonable level?

I realize I have a lot of questions. This is my first pool and I learned everything so far from reading about pool chemistry from this site. Thanks for taking the time to share information!

-Ankur

 

[ajw22]

When I run the backwash, it runs to a sewer drain but overflows a bit (see photo). Is this an issue? I have a link to a video of what it looks like here.

Pleased load your video to YouTube mark it PUBLIC, and post a share link here.

Picture Posting and Resizing - Further Reading

www.troublefreepool.com

1. Is it reasonable to drain the pool to lower the CYA to make the high FC SLAM levels more attainable for eliminating mustard algae?

Yes.

1. Can I drain the pool by (1) setting my valve completely to the vacuum port, (2) opening the backwash, and (3) turning on the pump so that the vacuum sucks out all the water? Or is there a more straightforward way?

Use a submersible pump for draining. Ever pool owner should have a submersible pump.

Submersible Pumps - Further Reading

www.troublefreepool.com

Your pool pump probably cannot drain below the skimmer which is not enough for what you need. And you do not want to risk an expensive pool pump running dry and getting damaged.

Draining - Further Reading

www.troublefreepool.com

1. How do I calculate how much of the pool to drain to get my Calcium levels down to a reasonable level?

To get your CH down around 400 you need to drain about 60% of your pool.

 

[ankur496]

Thanks for your reply

Here's a YouTube video

 

[wireform]

If you extend the drain pipe maybe 3 feet it may not overflow but as was advised before me, using the expensive pool pump is risking it besides you need much more water to be exchanged which this method won't work regardless.