Partial drain procedure...

tfpusername

Well-known member
Apr 23, 2017
89
Las Vegas
Little confused on the whole partial drain procedure (trying to lower Calcium Hardness and CYA in a fiberglass pool). Couple questions...

1.) Since we don't have any storm drains here, I'm hoping I can use a slow pump and drain the water onto my garden/lawn? If it's a hot day, and the chlorine is low (< 1ppm?), and I move the hose around every hour or so, is this safe?

2.) What kind of pump should I be looking at? Something like this...? https://www.amazon.com/Superior-Pum...ords=pool+draining+pump&qid=1597632370&sr=8-3

Thanks for any tips!
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,646
Rancho Cucamonga, CA
The preferred method according to LVVWD is draining to the sewer. Are you connected to the sewer? Do you know how to locate your sewer clean out?

You can drain to the landscape, but your soil will only take so much before it saturates and runs off to wherever your rainwater drains. The pump you linked should do the job.

Make sure you understand the risks of "draining" a fiberglass pool. A no-drain water exchange may be a better option depending on the volume you need to exchange.

 
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tfpusername

Well-known member
Apr 23, 2017
89
Las Vegas
No idea where a sewer drain would be outside. The pool is way in the back, so doubt it's anywhere close.

So a partial drain is just draining and refilling at the same time? A slow trickle drain like that may work better if I plan on dumping the water onto my lawn (I don't care if it the whole process is spread out over a couple days).

Will such a trickle drain really fix my insane Calcium Hardness though? 500+ppm. And do I need a special low flow pump (didn't see any kind of speed adjust on that one I linked).
 

Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,646
Rancho Cucamonga, CA
I haven't done a no-drain exchange, but one key to success is matching the rate of discharge (sub-pump) the rate of refill (garden hose). A 1/4 hp pump should be a close match to the rate of fill from a garden hose. If you're interested, @mknauss is the resident expert in water exchanges. A CH of 550 is not much to worry about (for now). How high is your CYA?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,824
Laughlin, NV
You have a sewer clean out I would bet. I do not know of any Las Vegas homes that are still using a septic tank. Look on the side of the house, front, etc. Our house has several.

With a fiberglass pool, many frown on just draining it. In Las Vegas, you can most likely get away with it. I have started to use the water exchange method as I can use my small sump pump for it. It is described in the article linked earlier in this thread.

If you post a full set of test results, from your test kit, I can provide some guidance. CH of 500 is not really high. Your fill water CH is 250+ppm.
 
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tfpusername

Well-known member
Apr 23, 2017
89
Las Vegas
Well last I checked with my taylor kit my CH was well over 500+. A quick test strip had it off the chart 500+ as well. But it's also the CYA, which seems to be creeping up above 100. So since I haven't drained the pool in 3+ years, I figured now would be a good time.

There is a water shut off box buried in my front yard, but I don't see any drain. Although if there was a drain in the front it's a looong way from the pool (and over a tall wall)...

I think my only option is to drain into the back yard. It's a big backyard, so I can drain far away from the pool. And if I do a drain and fill (just a garden hose rate of water right?), I have a feeling the water will evaporate near instantly in the 110 degree sun.

So if I stick that 1/4 gallon pump (linked above) into the deep end, with the hose draining to a corner of my yard (far away from the pool), then stick a garden hose in the shallow end running at the same volume, that's all there is to it?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,824
Laughlin, NV
The Exchange method is simple but if you do not follow some basic items, it will be very inefficient.

Water temperature. Fill versus pool. My fill water temperature is a good 10F warmer than our pool water temperature right now. Check yours.
I test using my Taylor CH test to 1000 ppm easily. Up to you, but if the CH is 500, a half drain will be fine IF your CYA is 100. If CH is 1000, then a full drain/exchange is warranted.

I use a 1/2 hp sump pump with a 3/4" garden hose strung to my clean out. With that, I get about 7 gpm. Your water spigots should keep up with that. Do measure what your actual exchange rate is using a 5 gallon bucket timed.

So if your fill water is warmer, and your CH is well above 500 ppm, then putting the pump on bottom(deep end) and filling at surface (see explanation in article), your exchange will work. Plan to exchange at least 10% more water volume than what you need to achieve your goals. Pool pump and auto fill need to be disabled during this process.
 
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