Strategy For Partial Pool Drain

Ssouthar

Bronze Supporter
Dec 27, 2019
27
Elk Grove, Ca
I figured this was the most logical place for this post. Appologies if I guessed wrong. <grin> So on advise I've gotten here on TFP, I'm going to attempt to do a partial drain of my in-ground pool to lower my CYA levels. The issue I'm concerned about is how to do it correctly given my current plumbing config. The pool was built long before we moved in - built around 2005 I think. It has a skimmer on either end (shallow and deep end) and it has a pool cleaner port on the side. It's plumbed to switch only between skimmer and cleaner. There is no valve or position that I can see that allows for pulling water from a drain at the bottom of the pool. The way I see it, it's a simple work around to set the valve to pool cleaner only and as long as the pool cleaner is at the bottom of the pool, I'm pulling water only from that device and nowhere else. Does that sound about right? I have an auto-filler which I've shut shut off the valve for. I'm only going to drain off about half the water. Here are a couple images of the setup for what it's worth. PoolDrain.jpg
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
16,926
Bedford, TX
S,

Your plan will work, but I would not walk off a leave it while in process... As the water gets lower, it will be harder to suck the water through the little vac hose. Half way down should not be problem, but I would keep an eye on the pump to make sure it did not run out of water.

Thanks,

JIm R.
 
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Rancho Cost-a-Lotta

Silver Supporter
Apr 10, 2018
1,408
Rancho Cucamonga, CA
I tried what you're thinking about. I hooked up my vacuum hose to the accessory port and weighted down the other side of the hose so it would sit on the bottom. I was afraid my cleaner would come out the water on a step or seat. It didn't work. My hose is made up of 3-4 foot sections and too much got sucked in through the joints causing cavitation. I don't think these fittings are designed to be air-tight. Even with a one-piece hose you'd probably leak air where the hose connects to the port. It wouldn't hurt to try as long as you're around when the water level drops below the accessory port.

Since my accessory port is only about 9" below the surface, I ended up draining to just above the port and using three hoses to siphon down below that point. Of course, a submersible pump is the best way to drain.
 
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Newdude

Well-known member
Jun 16, 2019
2,433
NY
I don't think these fittings are designed to be air-tight
Under normal circumstances they don’t need to be. The worst that happens is they suck in a little extra water at the connections.

Even with a one-piece hose you'd probably leak air where the hose connects to the port.
Right again ! I have one and it sucks air like no tomorrow. Makes a kissy noise and everything. With a full pool it’s easy to splash some water into the connection. Not possible for an empty pool.
 
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Ssouthar

Bronze Supporter
Dec 27, 2019
27
Elk Grove, Ca
S,

Your plan will work, but I would not walk off a leave it while in process... As the water gets lower, it will be harder to suck the water through the little vac hose. Half way down should not be problem, but I would keep an eye on the pump to make sure it did not run out of water.

Thanks,

JIm R.
Thanks Jim! Yep, I definitely don't plan on leaving it unattented. Will not let it run overnight.
 

Ssouthar

Bronze Supporter
Dec 27, 2019
27
Elk Grove, Ca
I tried what you're thinking about. I hooked up my vacuum hose to the accessory port and weighted down the other side of the hose so it would sit on the bottom. I was afraid my cleaner would come out the water on a step or seat. It didn't work. My hose is made up of 3-4 foot sections and too much got sucked in through the joints causing cavitation. I don't think these fittings are designed to be air-tight. Even with a one-piece hose you'd probably leak air where the hose connects to the port. It wouldn't hurt to try as long as you're around when the water level drops below the accessory port.

Since my accessory port is only about 9" below the surface, I ended up draining to just above the port and using three hoses to siphon down below that point. Of course, a submersible pump is the best way to drain.
Ah! Good point Rancho and something I had not considered. I'll see where I'm at when I get down to the level of the side cleaner port. Good news is I need to buy a submersable pump anyway because I just had a tankless water heater installed and I'll need it for descaling. Had one at the old house but left it for the new owners not knowing if I'd need it at the new place. Will need to get one though with a long enough power cord to reach the bottom. Pool is only 7 feet deep.
 
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Ssouthar

Bronze Supporter
Dec 27, 2019
27
Elk Grove, Ca
I figured this was the most logical place for this post. Appologies if I guessed wrong. <grin> So on advise I've gotten here on TFP, I'm going to attempt to do a partial drain of my in-ground pool to lower my CYA levels. The issue I'm concerned about is how to do it correctly given my current plumbing config. The pool was built long before we moved in - built around 2005 I think. It has a skimmer on either end (shallow and deep end) and it has a pool cleaner port on the side. It's plumbed to switch only between skimmer and cleaner. There is no valve or position that I can see that allows for pulling water from a drain at the bottom of the pool. The way I see it, it's a simple work around to set the valve to pool cleaner only and as long as the pool cleaner is at the bottom of the pool, I'm pulling water only from that device and nowhere else. Does that sound about right? I have an auto-filler which I've shut shut off the valve for. I'm only going to drain off about half the water. Here are a couple images of the setup for what it's worth. View attachment 124747
Success! I ended up buying a submersible 1/2 HP pump to finish the planned drain. Drained it only 50% but that was enough to lower my CYA to 30. After refilling and adjusting chlorine and PH, this is what I ended up with. Hopefully, this is much better. Thanks for the suggestions.
5.6,FC
0.0, CC
7.6, pH
110, TA
210, CH
30, CYA
47 °F , TEMP
-0.34, CSI
 
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thephatp

Well-known member
Jul 8, 2018
82
Austin, TX
Success! I ended up buying a submersible 1/2 HP pump to finish the planned drain. Drained it only 50% but that was enough to lower my CYA to 30. After refilling and adjusting chlorine and PH, this is what I ended up with. Hopefully, this is much better. Thanks for the suggestions.
5.6,FC
0.0, CC
7.6, pH
110, TA
210, CH
30, CYA
47 °F , TEMP
-0.34, CSI
@Ssouthar where was your CYA when you started? I'm in a similar position. I'd rather not drain the whole pool if I don't have to. I'm currently sitting at 7.7 pH, 70 TA, 260 CH, but 90 CYA @ 61°F. :(

Also, did you do anything specific to avoid the issue of the shell coming up out of the water? I've seen horror stories where the lack of pressure from within the pool shell caused it to push up out of the ground and ruin everything.
 

Ssouthar

Bronze Supporter
Dec 27, 2019
27
Elk Grove, Ca
@Ssouthar where was your CYA when you started? I'm in a similar position. I'd rather not drain the whole pool if I don't have to. I'm currently sitting at 7.7 pH, 70 TA, 260 CH, but 90 CYA @ 61°F. :(

Also, did you do anything specific to avoid the issue of the shell coming up out of the water? I've seen horror stories where the lack of pressure from within the pool shell caused it to push up out of the ground and ruin everything.
Hi! Sorry for the late reply. My CYA was around 90 before draining. Since that last post, CYA seems stable around 40 to 45. I don't know enough about the pool shell problem to advise other than to say I had no issues. I did not drain it all the way, only about 2/3s. I know the owner before me drained it completely a few times over the past 18 years with no issue. Doesn't that have something to do with water table in the area? I thought I remembered reading that high water table is a potential problem when draining a pool. We have a real drainage issue in our yard so I too was very worried. That's why I only drained it two-thirds.