Main Drain Suction Questions

[Dodger]

As far as the Main Drain goes, most older pool had the main drain plumbed into the bottom of the skimmer. Depending on the skimmer there would have been a floating device or a plastic sliding door to allow the main drain to work. Almost every older pool that I have seen these devices are missing. It is not a big deal as there are thousands of pool out there with no operating main drain and they all work just fine.

Jim, can I ask some questions about this? Our pool is more than 25 years old and has this configuration. In each of our 2 skimmers, there is a float valve beneath the skimmer basket - not missing! . If I understand correctly, a fully closed plastic "door" on each of the 2 floats should put "all" the pump intake force to the main drain. Is that true?

And if the plastic door is fully open, is it fair to say that most/all of the pump intake is through the skimmers?

What about partially closed plastic doors? It seems impossible to gauge what percentage is coming from the main drain versus skimmers unless the doors are fully closed.

Above is how they should work theoretically. My last question is how they would work with a missing o-ring. There are 2 o-rings in the float assemblies. Mine both have the upper/smaller o-ring, but the lower one is missing, so I don't think I really get a full seal when the plastic door is closed. Any comment about how that will affect the pull from the main drain? I like to close off these doors when I'm brushing pollen to the main drain. Is that the right idea?

 

[Jimrahbe]

Re: Parents' Pool Questions

Jim, can I ask some questions about this? Our pool is more than 25 years old and has this configuration. In each of our 2 skimmers, there is a float valve beneath the skimmer basket - not missing! . If I understand correctly, a fully closed plastic "door" on each of the 2 floats should put "all" the pump intake force to the main drain. Is that true?

And if the plastic door is fully open, is it fair to say that most/all of the pump intake is through the skimmers?

What about partially closed plastic doors? It seems impossible to gauge what percentage is coming from the main drain versus skimmers unless the doors are fully closed.

Above is how they should work theoretically. My last question is how they would work with a missing o-ring. There are 2 o-rings in the float assemblies. Mine both have the upper/smaller o-ring, but the lower one is missing, so I don't think I really get a full seal when the plastic door is closed. Any comment about how that will affect the pull from the main drain? I like to close off these doors when I'm brushing pollen to the main drain. Is that the right idea?

Dodger,

In theory, with the flap closed the Main Drain is on and the skimmer off..

That said, I had zero luck getting the floating space ship to work...

I could never get them to seal well enough to get the main drains working. For me, there is no benefit to having the drain, so I did not screw with it for very long. Both of mine have missing O-Rings, assuming that they were ever there to begin with???

Both of these pools are at rent house that have robots, so not having the main drain has never been an issue.

Thanks,

Jim R.

 

[Dodger]

Re: Parents' Pool Questions

I could never get them to seal well enough to get the main drains working.

Thanks Jim. How can I really assess if my main drain is "working"? Is there a dye test, or should I be able to observe pollen/dirt being pulled to the main drain when in this skimmer-closed mode?


edited: I should have searched on the forums first. I will read some of the posts I've just found about this. Thanks!

 

[Jimrahbe]

Re: Parents' Pool Questions

Thanks Jim. How can I really assess if my main drain is "working"? Is there a dye test, or should I be able to observe pollen/dirt being pulled to the main drain when in this skimmer-closed mode?


edited: I should have searched on the forums first. I will read some of the posts I've just found about this. Thanks!

Dodger,

As a general rule searching the forum will almost always produce better answers than I can come up with...

At my house, my Main Drain is run to a Jandy valve at the equipment pad. Even when fully turned on, the amount of suction at the main drain is basically invisible. It is not at all like the skimmer, where you can actually see water being sucked in. If you had a big cloud pollen all around the main drain, most of it would just drift away.

Thanks,

Jim R.

 

[Dodger]

Re: Parents' Pool Questions

Dodger,

As a general rule searching the forum will almost always produce better answers than I can come up with...

At my house, my Main Drain is run to a Jandy valve at the equipment pad. Even when fully turned on, the amount of suction at the main drain is basically invisible. It is not at all like the skimmer, where you can actually see water being sucked in. If you had a big cloud pollen all around the main drain, most of it would just drift away.

Thanks,

Jim R.

Actually, that helps a lot! So with a true mechanical valve diverter, the suction still isn't visible. (Actually, that seems a lot better for safety.) I won't sweat this issue very much then.

 

[Chrissykr]

Re: Parents' Pool Questions

Thanks Jim. How can I really assess if my main drain is "working"? Is there a dye test, or should I be able to observe pollen/dirt being pulled to the main drain when in this skimmer-closed mode?


edited: I should have searched on the forums first. I will read some of the posts I've just found about this. Thanks!

When I brush my pool you can see the stuff being pulled into the drain itself. Also, debris tends to collect on mine so I am always checking and brushing stuff off of it. I know mine pulls pretty good because I have to turn the pump off for the robot to clean it.

 

[Dodger]

Re: Parents' Pool Questions

When I brush my pool you can see the stuff being pulled into the drain itself. Also, debris tends to collect on mine so I am always checking and brushing stuff off of it. I know mine pulls pretty good because I have to turn the pump off for the robot to clean it.

Oh wow. Okay, so that's another data point. I guess it varies from pool to pool. Thanks for that info!

 

[PoolGate]

I just this weekend threw out those 2 "spaceships" that were included with my skimmers as I finally got tired of looking at them. PB did not use that connection on the skimmer and said they were archaic and no one used them anymore. My floor drain is independently run to the equipment pad.

 

[Dodger]

I'm wondering if someone can explain these pics. Looks like I have main drains on the walls (in addition to the floor main drain in the deep part of the pool.) One is positioned right below one skimmer, and the other 2 are positioned a little to the side of the second skimmer at the far end of the pool. Am I correct assuming these go into that main drain line at the bottom of each skimmer? If yes, then can I still assume the floor main drain also plumbs to the bottom of one or both skimmers? I'm curious more than anything else.

Also wondering if this is a normal configuration or dated from a few decades ago. What is the thought behind wall drains and how do they affect water circulation? Two of these are right next to the returns.

View attachment 71290View attachment 71289

 

[Jimrahbe]

Dodger,

I "assume" these ports are connected to the skimmer. Skimmers normally have two ports.. one goes to the suction side of the main pump and the other port can be connected a couple of different ways. One, it can go to the Main Drain at the bottom of the pool, two it can just be plugged and go nowhere, and three, it can go to a port in the side of your pool. I believe when done this way they call it an equalizer port.

Basically, they use the little spaceship device and if the water falls below the level of the skimmer, instead of your pump sucking air, it sucks water from the ports just below the skimmers. That said, I have never see any that look like the ones in your pics. I have equalizer ports and they look like normal eyeballs..

Thanks,

Jim R.

 

[Dodger]

Thanks Jim! I will read up on "equalizer" ports.


Without digging up concrete, I guess there's no way for me to know if the main (floor) drain merges with an equalizer port before going into the second skimmer port. Or if the main drain is plumbed to the pump intake further downstream.

 

[needsajet]

You can use food colouring in an eye dropper. Blue is really intense so you can water it down. Try setting things various different ways, and see when the dye gets sucked in.

Suction can create profound risks to children and adults, due to potential for entrapment. If you have any old suction ports in walls or the floor, be sure they have properly attached and compliant covers.

Here's some examples of good drain covers: pool drain covers - Google Search

Here's a bad one: pool drains - Google Search

If there's an eyeball anywhere sucking water, swap it over to a compliant drain cover.

If wall suction ports are plumbed back to the pump (for example a cleaner port) they should have properly self closing flaps that disable them when not in use.

If you have a single main drain, consider disabling it.

It's great that you're sorting this all out. I think it's really important to know exactly how the suction side works and which valves/diverters affect what.

 

[Jimrahbe]

dodger,

If your skimmer has two ports in the bottom, you can tell which is connected to the main pump by feel.. One port will have a lot of suction and the other will not. Obviously with the pump running...

To see if the other port is connected as an equalizer port, you can simply shove a garden hose in the skimmer side and see if you can feel the water coming out the wall port. This will work for seeing if it is connected to the Main Drain also, but not quite as obvious. I don't believe it is normal to have the port used for both the main drain and equalizer.. It is usually one way or the other. When connected as an equalizer, the main drain is generally run back to the equipment pad.

But, different areas do different things, so what is common here may be different where you live.

Thanks,

Jim R.

 

[Chrissykr]

I have one of those on the side of my pool. I have no idea if yours is the same or not. Mine is a release valve for the main drain. According to my pool company if the main drain gets clogged or something gets caught in it, then it will pull from that thing shutting down the main drain. That line is always the last one they shut down when they close the pool.

 

[Dodger]

You can use food colouring in an eye dropper. Blue is really intense so you can water it down. Try setting things various different ways, and see when the dye gets sucked in.

Will try this at the equalizer ports. No way I'm dye testing the main drain in 50 degree water! Maybe next summer.

If you have a single main drain, consider disabling it.

Can you expand on this recommendation? Forgot to mention that all our covers are VGB compliant; they were installed this summer during the remodel.

dodger,

If your skimmer has two ports in the bottom, you can tell which is connected to the main pump by feel.. One port will have a lot of suction and the other will not. Obviously with the pump running...

To see if the other port is connected as an equalizer port, you can simply shove a garden hose in the skimmer side and see if you can feel the water coming out the wall port. This will work for seeing if it is connected to the Main Drain also, but not quite as obvious. I don't believe it is normal to have the port used for both the main drain and equalizer.. It is usually one way or the other. When connected as an equalizer, the main drain is generally run back to the equipment pad.

But, different areas do different things, so what is common here may be different where you live.

Thanks,

Jim R.

Thanks Jim. I do know which one is to the pump, as I use it all the time for my vacuum hose. Good suggestion about the garden hose and I will give it a try in addition to the dye testing.

Based on what you guys are saying and some typical equalizer port diagrams I've found on the web, I suspect my main drain line merges with the skimmer lines right before they come above ground at the equipment as one line. Above ground, there is only a pool intake and a spa intake joined into the Jandy Actuator.

 

[needsajet]

If you have a single main drain, and it's plumbed back to the pad, you can close the valve and remove the handle. It's still available for draining if that's ever needed, but risk is eliminated in the meantime. You can also set it to a trickle and remove the handle. If it's plumbed into the skimmer, the port is often threaded inside, and you can put a threaded PVC plug in, or else use an expanding plug.

 

[Dodger]

If you have a single main drain, and it's plumbed back to the pad, you can close the valve and remove the handle. It's still available for draining if that's ever needed, but risk is eliminated in the meantime. You can also set it to a trickle and remove the handle. If it's plumbed into the skimmer, the port is often threaded inside, and you can put a threaded PVC plug in, or else use an expanding plug.

I may not be able to determine if it's plumbed to the skimmer till next summer, so that would have to wait unless I get an obvious visual result from Jim's garden hose test. Anyway, I've seen pictures of capping it with a pvc plug, so I think I understand. But if the equalizers are also plumbed to that same skimmer port, then I'd be capping them off too. So I'd have to consider the impact of capping those.

There is no individual main drain valve at the equipment. The only valve is the JVA that toggles between spa intake and pool intake. The pool intake side of the JVA is skimmer + main drain (assuming main drain is active). So in the former case you describe, I don't see a way to block off pull from the main drain without also affecting the skimmer.

 

[Dodger]

Re: Main Drain Suction Questions + Equalizer Ports

Okay, so here's what I've tested and learned:

The side of the pool with a single equalizer port is definitely working as such. The garden hose clearly blew out some leaves through the equalizer cover plate, and dye is sucked into the cover plate when the pump is running. Interestingly, the dye still goes in even with the Skimmer Float Valve door fully open. So it's an always-on port, perhaps with some suction amount variability.

The side of the pool with dual "equalizer ports" did not produce any conclusive results. There was no obvious outflow from the garden hose, and neither of the cover plates took in any dye with the pump on. The garden hose test also caused some burping out of the non-pump skimmer port, so it seems there is some air in there (pump was off during this test). I'm thinking about snaking that line. Would that be appropriate?

Or, it's possible these 2 ports are NOT connected to the skimmer and/or have some other purpose. After all, unlike the single port on side 1, these 2 ports are not directly below the skimmer. While they are 18 inches down like the first one, they sit ~16 and ~46 inches off to the side of this skimmer. This is the side of the pool that is close to the equipment, and those 2 "equalizer ports" are also very close to the spillover spa wall. Any ideas?

BTW, being up to your elbow in 49 degree water for minutes at a time is literally bone chilling!!

 

[mknauss]

The two ports -- could they be suction for the sheer descent pump? Normally that type of water feature is plumbed separately from the normal skimmer - filter system.

Take care.

 

[Dodger]

The two ports -- could they be suction for the sheer descent pump? Normally that type of water feature is plumbed separately from the normal skimmer - filter system.

Take care.

OMG, Marty. You are the man!! That's exactly what they are. I feel a little silly because I had not given any thought as to where the supply to that pump was coming from. The dye test just easily proved it.

It's so great to now know what these 3 ports are doing in my pool! Thank you TFPers!



This also leaves open the possibility or likelihood that my main drain is plumbed to this side skimmer port. Will test that next summer when the water is warm.