AZ partial drain for CYA; question about running filter


Well-known member
Jun 2, 2014
Phoenix, AZ
My CYA was over 80 and then I used tabs instead of liquid chlorine for the winter, so it probably spiked.

This afternoon I started a (slow 6gpm amazon pump) partial drain and now I'm realizing that it's 6pm and the water is nearly below the skimmer basket.

My question is if I should I start refilling in time for the pump to run tonight or can I miss a night (water temp around 60 and FCL of 16, pH 7.4)? This might mean doing a second drain next weekend and the outside temperature is starting to climb quickly as it's March. Plus I don't want to waste water.

A follow up for if I need to refill. Does the water need to be at the full level or is it fine to be just above the skimmer basket level?

Thanks everyone!


TFP Expert
LifeTime Supporter
Jun 7, 2011
Midland TX
If it is too low in the skimmer it will suck air, so not good. If it's a good bit lower than halfway the center of the skimmer mouth, that is risky. Can you reschedule the pump, or turn it off? Either way, you don't want to risk filling the pump with air.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

I don't believe that one day of not running the pump with an FC of 16 and water temp in the 60's will be a problem.


Jim R.


Well-known member
Jun 2, 2014
Phoenix, AZ
Jim was correct my levels were fine a night without the filter.

Unfortunately I'm on round two. I drained 17 hours (5100 gallons) and then let the new water mix and circulate for a week. Tested the CYA around 90 still, so i was worse off than expected.

New question for round 2... It's now in the high 80s air temp in Phoenix. I need to drain for 24 hours based on needing to replace half my 12k gallon at 5gpm. Then 20+ hours to fully refill from the spigot. Do I have to worry about the pool raising out of the ground or anything like that?


LifeTime Supporter
TFP Guide
Feb 6, 2015
Chandler AZ
In Phoenix, you usually don't have to be too concerned about the pool popping out of the ground as our water table is quite low.

I know your intent is to lower the CYA, but how high is your CH? And what's the CH of your fill water? If your pool water CH is extremely high, you may need to drain more than you planned to get the CYA down.

It might be better to rent a sump pump from Home Depot or buy one from harbor freight. Best to drain it fast - 6 GPM is awfully slow. And you'll save water by not having to do multiple small drains. Is it possible to use multiple hoses to refill?

If you go with your present plan, it may be best to hose down the exposed pebble to keep it from getting too hot.
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