Treating Inground Fiberglass Pool That Was Flooded By Hurricane Sandy

by Jane

We opened the rotten smelling "black lagoon" late in the season and superchlorinated it for a couple of days (as emptying and refilling not an option right now due to no $$) it cleared up to crystalline condition, but of course now left with heavy salt content.

I read your response to Keith about draining and filling at same time. Would like to try this option. the pool is 8,000 gallons.. how long would this take do you think to empty/fill to get salt content to harmless levels.. and what is harmless level? this is chlorine pool with a Hayward Ecostar sp3400vsp pump. Appreciate any advice.

Thanks for the question Jane

Yes I've had several questions about this very subject and pretty much give the same answer. Flood water is very dangerous because you have no idea where the water came from or what's in it. It could be sewer water, bacteria from dead animals, huge amounts of salt water, etc...

Most salt pools run the salinity between 2500 - 4500ppm. This is barely detectable to taste. The salt level is not the biggest issue, but the organic and inorganic matter that comes from flood water.

How long it takes is dependent on the gallons per minute (GPM) of the pump and the GPM and psi of the fill hose. At 80spi for a garden hose, and I believe this is the norm, the THEORETICAL flow you might have is:

1/2" Garden Hose = 66 Gallons per minute
5/8" Garden Hose = 104 Gallons per minute
3/4" Garden Hose = 149 Gallons per minute

I think this is under the best of circumstances. If you have a 1/2" hose pushing 66 GPM you could theoretically fill your pool in a little of 2 hours.

This is a rough estimate because many factors need to be taken into consideration and there's a huge mathematical equation for flow rates. Here's one:

Pressure = 80 psi = 80/2.54*2.54*2.2046 =5.62 kg/sqcm
h, head =5620 cm of water= 56.20 m

dia of hose = 3/4" = 2 cm
Area= pi*4/4= 3.14 sqcm

velocity of flow = Sqrt( 2gh) = sqrt ( 2* 9.81*56.20) =
33 m/sec

Flow rate = 33*3.14/10000=0.0104 ***/sec= .6256 ***/min=625 .6 litres/min = 137.5 imp gal/min=165 us-gal/min

Honestly, my brain doesn't
work like that so here's what I'd do. Get a 5 gallon bucket and a stop watch or use your cell phone. It probably has this function. Start the fill and the stop watch. When the bucket is full you'll have 5 gallons. Let's say it's 5 seconds per gallon, so that's 25 seconds per 5 gallons.

Your pool is 8,000 gallons, so there's 1600 five gallon buckets. Each bucket takes 25 seconds to fill so multiply 25 X 1600 = 40,000 seconds to fill the pool. Now we need to know how many minutes that is, so divide 60 minutes per hour into 40,000 and that's 667 minutes, or about 11 - 12 hours. I would allow an extra 3 - 4 hours to drain and fill to compensate for any errors that may happen.

Again this is theoretical but you can have a good ballpark estimate.

I had to partially drain and refill the Y pool occasionally using this procedure when the guards put it too much salt or calcium. I'd turn the skimmers off and hook up the fill hose. It would take about 2 hours to get the salinity from 5000ppm down to 3500ppm, but this was an 80,000 gallon pool with a 5" PVC pipe.

As the other posts say, I've never taken care of a flood issue. My pool route was in Arizona and the biggest problem I had was windstorms and dirt, never polluted ocean water. In reality, and from personal experience, doing a drain and refill at the same time does work, however, I have no personal knowledge how effective this technique is with a pool that has been flooded with contaminated water.

Please understand that this is only my opinion and should be taken as such. Do your homework and due diligence and choose the best method that works for your situation.

If you feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of $35 per hour and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.

Hope this helps and have a great Summer.


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