Tecniques for remove a large, but measured amount of water

dfiletti

LifeTime Supporter
Jun 12, 2008
76
Thornton, PA
OK, so I'm resigned to replacing ~12,000 gallons of water in my 28K pool to lower my CH from 600 to a more mid-range number.

What's the best technique? I could drop a garden hose in, start a siphon, measure how long it takes to fill a 5 gallon bucket and multiply when to stop the siphon. But as the water get's lower, won't the flow rate decrease? Are my accuracy concerns unwarranted?

I thought about renting a commercial 3" garbage pump -that would certainly be faster, but again, I have concerns about calculating accurately.

Is there an easy way to do this? Do some of these pumps have a gallon-age meter?

Any help would be appreciated.

Thanks!

Dan
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,423
Pleasanton, CA
This year I replaced about half of my water "in place" so both draining and filling at the same time. I set the suction up to draw only from the main drain in the deep end and at the same time I added water via the opposite skimmer so as to keep the new and old water somewhat separated. I set up the plumbing so that the pump discharges through a garden hose directly into the drain but I also had to set the pump on low speed so the drain rate would not exceed the fill rate. Plus a garden hose has a lot of head loss so low speed was really the only option. This setup drains the pool at about 10 GPM and the fill rate was about the same. I used a 5 gallon bucket to measure both and since the water level remains constant, the flow rates of both should be about the same throughout the process. After 24 hours, I had about 1/2 the pool water replaced. Based upon salt level measurements afterwards, there did not seem to be a lot of mixing going on so it seemed to work ok. However, the more water that is replaced, the harder it will be to keep the new and old water separated.

You don't seem to have a similar setup but instead you could use a small drain pump found at the local hardware store instead of your main pump. If you can match the drain and fill rates plus get a good estimate of both, you can then calculate about how long it will take to replace the desired amount of water. You just need to make sure you fill and drain from opposite ends of the pool and water is fairly still with not a lot of mixing going on.

BTW, this technique is a much safer way to replace water and does not put the pool at risk for lifting should there be any ground water.
 

another one

Well-known member
Jul 1, 2010
49
Seattle area, WA
AT 802 square foot, if you lower the water 1 inch, you remove 500 gallons. Lowering the water 2 feet will remove 12,000 gallons. So, if you pump, you can measure the rate from the pump, or just watch the water level and when you reach the down 2 foot mark, start filling.
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
23,052
SouthWest Alabama
I use my vacuum hose to siphon water out our pool. That 1½" hose will drain a lot of water in a hurry. As A.O. said, 2' of water is about what you need to empty. You could even tie the hose end 2' below the surface and it'll act as an automatic shutoff.
 

dfiletti

LifeTime Supporter
Jun 12, 2008
76
Thornton, PA
OK, I really appreciated the water level input, it made it easy to just simply drain to a particular depth. Thanks.

So in the end, I used the vacuum hose, in conjunction with the pool pump. I had to close the skimmer inputs, and use the main drain only, and pump to waste, but it work really well. It only took a few hours, double teaming it like that. I'm in the process of refilling with two hoses, but, as you might imagine, it's going in slower than it came out.

Again, thanks again for this input.

Dan
 
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