Help with Test Results

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griego

Active member
Nov 9, 2018
33
Miami
#21
No hill , but 3 miles from the ocean. I found some data online close to my house if it helps .

DESCRIPTION:
Latitude 25°39'03.9", Longitude 80°20'18.0" NAD83
Miami-Dade County, Florida , Hydrologic Unit 03090202
Well depth: 91 feet
Land surface altitude: 12.3 feet above NGVD29.
Well completed in "Biscayne aquifer" (N400BISCYN) national aquifer.
Well completed in "Biscayne Limestone Aquifer" (112BSCNN) local aquifer
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
3,711
Northern NJ
#23
None of us can tell you with certainty if you are safe to drain 50% of your pool. I would say the risk is low if you drain 50% and immediately refill the pool. But in an area like FL the risk is there.

@mknauss can explain a water exchange process that keeps the pool full while exchanging old with new water.

Here are some articles to read:

Why Concrete Pools Pop Up Out Of The Ground: Reasons, Problems & When To Worry - Buyers Ask

http://www.pegroup.com/publications/Tech-201305.html

Can Concrete (Gunite) Pools Float? Crazy Pictures
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
3,711
Northern NJ
#25
Interesting point, I wasn't aware of that.. Curious to here how an exchange water process looks like . thx
Copied from one of @mknauss posts:

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end (through a skimmer or into a bucket on a step so you lessen the water disturbance) you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
3,711
Northern NJ
#27
I see. So how shall I know how much water I pulled out and to stop , when I am filling it from the shallow end ? Thx
You can get a flowmeter like discussed here - Got some drainin' to do...

Or you can time how long it takes your fill hose to fill a known gallon bucket and calculate the time it will take. It will not be a problem if you replace more water than planned. Your CYA will be lower and you may need to add some stabilizer.