Bottom drain- do you use them ?

[Meadow]

If a main drain that is plumbed to the skimmer has that much suction it is an entrapment issue. Those flaps to cover the back hole are only to be used fo vacuuming purposes. That is the only use of a drain plumbed to the skimmer. “Supposedly” the water flowing over the front hole will create a Venturi type suction and pull water up the line....right...I have some swamp land for sale too....

That is why it is very important to have at least 2 main drains tied in a single pipe that runs back to the combo skimmer. I have a dedicated suction side port on the wall for vacuuming and I never use the skimmer port for that purpose. Often, I closed the combo skimmer float valve if I want to pull water from the drain only. Not sure why the combo skimmer is useless to you but I do respect your opinion!

 

[Dirk]

If a main drain that is plumbed to the skimmer has that much suction it is an entrapment issue. Those flaps to cover the back hole are only to be used fo vacuuming purposes. That is the only use of a drain plumbed to the skimmer. “Supposedly” the water flowing over the front hole will create a Venturi type suction and pull water up the line....right...I have some swamp land for sale too....

Have I misunderstood this all this time? That is not my understanding of how a main drain plumbed to skimmer can work, at all. I thought one could add a diverter plate to the skimmer to completely balance how much water is drawn from either skimmer or drain. Nothing to do with any sort of venturi effect. And I thought I read of other systems that incorporate some sort of float valve that could also balance flow, but if the water level dropped below the skimmer opening, the float valve would operate such that all the water would be drawn from the drain, and protect the pump from running dry. And that the use of dual drains and the entrapment issues have nothing to do with where your drain is plumbed to, the potential danger exists either way, so the dual drains are required whether the drain line runs to the pad or the skimmer. You're making it sound as if a drain plumbed to a skimmer is like having no drain at all, and I can't wrap my head around how that could be true.

What do I have wrong there?

 

[Meadow]

/\ this! You got it right, Dirk! It is impossible to use the combo skimmer holes for vacuuming if the float valve or equalizer is in place! I guessed, Pool_Medic was misinformed!

 

[Dirk]

I have a combo skimmer but never had the diverter, so never saw for myself how that works. It was explained to me by my x-pool-guy. I deleted the drains in a remodel, so it's all a non issue now. Since I never had the diverter, my drains were never active, so I knew ahead of time deleting the drains would have no affect on anything. I also have a dedicated suction port, but I use an automated three-way back at the pad to control flow between skimmer and vacuum, to optimize both. So in answer to the OP, no, I don't use a bottom drain, never did, and now that it's gone I don't miss it.

I suppose I have given up the safety option of a float valve, that would protect my pump. But since I never had that either, I don't miss that either. That issue is somewhat covered by my autofill system, which keeps the water level from dropping. I suppose other scenarios could occur to defeat that (like if the autofill stopped working), but I chose to take that risk to rid myself of the drains. A lot would have to go wrong: I'd be away for several days at the same time the autofill failed during the high-evaporation season. Not at all farfetched, but very slim possibility. If I was really concerned, a web cam on my pool (which is in the works) and my automation would be a third fail safe. If I saw the water dropping, I could just shut down the pump and call somebody.

 

[PoolGate]

I have a combo skimmer but never had the diverter, so never saw for myself how that works. It was explained to me by my x-pool-guy. I deleted the drains in a remodel, so it's all a non issue now. Since I never had the diverter, my drains were never active, so I knew ahead of time deleting the drains would have no affect on anything. I also have a dedicated suction port, but I use an automated three-way back at the pad to control flow between skimmer and vacuum, to optimize both. So in answer to the OP, no, I don't use a bottom drain, never did, and now that it's gone I don't miss it.

I suppose I have given up the safety option of a float valve, that would protect my pump. But since I never had that either, I don't miss that either. That issue is somewhat covered by my autofill system, which keeps the water level from dropping. I suppose other scenarios could occur to defeat that (like if the autofill stopped working), but I chose to take that risk to rid myself of the drains. A lot would have to go wrong: I'd be away for several days at the same time the autofill failed during the high-evaporation season. Not at all farfetched, but very slim possibility. If I was really concerned, a web cam on my pool (which is in the works) and my automation would be a third fail safe. If I saw the water dropping, I could just shut down the pump and call somebody.

My skimmers were also this style but I actually had the diverters. My PB said they are archaic and no one installs them anymore. My main drains are not connected to the skimmer they go directly back to the pad. The extra port is plugged. Builder said just throw out the diverter parts.

 

[Dirk]

I don't know why the combo skimmer was ever created in the first place, as I can't see any advantage over plumbing to the pad, unless it was to save the PB a little trouble and expense. So yah, they should go the way of the dodo. But I feel the same about drains, too. As I mentioned, I plugged my extra port, to keep out the monsters. If I was to build a pool, I'd probably go way overboard and plumb every single port and skimmer back to the pad. PVC and a few extra valves are cheap in the grand scheme of a pool build... And I'd have one or two returns down low for circulation, no drains.

 

[Meadow]

And I thought I read of other systems that incorporate some sort of float valve that could also balance flow, but if the water level dropped below the skimmer opening, the float valve would operate such that all the water would be drawn from the drain, and protect the pump from running dry.

One advantage of having a combo skimmer fits the above statement. Plus, I can close the equalizer in the skimmer if I want to pull water from the drain only when heating up the pool. Our combo skimmer and vacuum port are plumbed into a 3-way diverter valve before the pump.

I don't have an autofill but a dedicated fill line operated manually. I'm losing about 1/2" of water a day at this time of the year and we have yet to experience a prolonged water supply interruptions!

Neeways, I think we just steered this thread off the track a bit! But in answer to the OP, yes I use the bottom drains along with the skimmer.