Partial Drain through through filter via skimmer and bottom drain connection

[seeesjames]

My CYA is >100. I don't even make it within 1/2" of the mark on my Taylor test kit before the black dot has disappeared. I opened the pool 2 weeks ago to a green mess, I couldn't see the deep end. I shocked it with Shockwave 73%, 4 lb worth of it over 2 days. The pool was ready to swim in a week later. I tested the water and verified the CYA test with the local pool store.

I would like to drain it, but can't figure out how. I can get the water to pump out of the bottom of the filter without a problem, there's a hose bib attached there. Once the water is below the skimmer I start blowing bubbles and lose flow. At the bottom of the skimmer is the connection from the drain. There is a simple valve which covers the two ports so water only moves between the pipes and not from the skimmer. The pump pulls water at varying rates, sometimes coming to a stop. How do I drain the water without fear of hurting my pump?

Please see the attached pictures of my equipment. There's no discharge to bypass the filter or heater I have to pull the water from the filter drain.

 

[JasonLion]

That kind of diverter valve in the skimmer almost never forms a really good seal. Even a small air leak will cause the pump to lose prime.

There are a couple of solutions. The simplest is to fill the pool at the same time you are draining it. This approach takes less total time, though it does use a bit more total water. Another approach that sometimes work is to use a cover pump or sump pump to pump water into the skimmer so that there is always some water to leak in, instead of air.

 

[seeesjames]

Nice, thanks! It's some sort of consolation that there isn't a better way to do it, as is.

Assuming I can keep the prime at the pump, would it be wrong to add a "T" between the pump discharge and the filter? I could add a valve that would help regulate the flow out, thus reducing the the pump sucking air. Keep the volume the same going in as out.... no slow downs to sucking air.

 

[jrs_diesel]

The second method that Jason posted is what I did when I drained 14,000 gallons last summer after we moved in (I had high CYA too). Like he said, the diverter does not form a perfect seal once it shuts, so whatever is left slowly consumed by the pump. What we did was keep an eye on the water level in the skimmer, and scooped a bucket of water from the pool to keep plenty of water in the skimmer as needed. This way the pump did not suck any air.

Do you have a pressure side cleaner line (for a Polaris cleaner)? If you do, you can increase your drain rate and shorten the drain time. We have one and I rigged up our vacuum hose to an extra pressure side fitting I had handy, and ran the other end of the hose to a cleanout fitting on the side of our house. Drained 14,000 gallons in about 5 hours.

 

[JasonLion]

Adding a "T" between the pump discharge and the filter is generally nice to have, but it won't help you keep the pump primed as you drain to any useful extent.