Not sure how my bottom drain works

macgyver89 · May 17, 2013

Hello TFP - Great site, helped me with my swamp, but I still have a lingering question. How does my bottom drain work, and what is its purpose.

Inside my skimmer, I have 1 hole which goes to the pump and another one (which had a gizmo in it) which I assume is connected to the bottom drain. What purpose does this serve?

Richard320 · May 17, 2013

macgyver89 said:
Hello TFP - Great site, helped me with my swamp, but I still have a lingering question. How does my bottom drain work, and what is its purpose.

Inside my skimmer, I have 1 hole which goes to the pump and another one (which had a gizmo in it) which I assume is connected to the bottom drain. What purpose does this serve?

Does the gizmo resemble this?

That is a diverter. If the little flap underneath it is completely closed, the suction is directed virtually 100% to the main drain. If it's wide open, 100% skimmer. If the water level in the skimmer drops too low, the float inside the diverter drops and it draws from the main drain so you don't run the pump dry.

It takes some experimenting to find the balance point for your pool. I watched the turbulence inside the skimmer without the diverter, then adjusted the door so there's just the slightest reduction in the skimmer. It worked out to just about halfway closed.

evanbone · May 17, 2013

That's a good idea. I didn't know they existed. Is any modification needed to my existing skimmer/basket setup? Are they standard sized? Do you just need it on one skimmer or both?

Richard320 · May 17, 2013

evanbone said:
That's a good idea. I didn't know they existed. Is any modification needed to my existing skimmer/basket setup? Are they standard sized? Do you just need it on one skimmer or both?

It depends on how your pool is plumbed. Some people have the second port blocked and a separate valve for the drain. I don't know about sizes. I measured my skimmer and went to the pool store and they had exactly one choice, but it would fit, so I bought it.

Mr. Blue · May 17, 2013

Richard, would you recommend adding one of these if not currently present?

macgyver89 · May 17, 2013

So right now I do not have one of those, I just have 2 holes in the bottom of my skimmer, does that mean my bottom drain is not being used? And I second Mr. Blues question as well.

Richard320 · May 17, 2013

To answer two in one: yes, I recommend it. Without something to force the suction to draw from the drain, it won't. It's much easier to let the skimmer fill by gravity than to move it through a pipe. With some flow down low, it prevents temperature stratification. You had to have felt it somewhere before: you dip your toe in and it feels nice and warm, then jump in and hit ice water.

Don't expect to feel any great suction down at the drain - if you have the required anti-entrapment covers you shouldn't. Brush a leaf or something towards the drain and see if it sits there or gets drawn in. Then you'll know. It also might be fun to check the water temperature on the heater before, and then check it again a minute or so after installing the diverter. I'm betting it will show cooler.

aviolentworld · Jun 1, 2013

i really have nothing to add except another question.

my far skimmer doesn't seem to pull in the water as fast as the closer one, i mean sometimes debris just floats by instead of getting sucked in(i understand that some pressure might be lost because of the longer distance). so i was doing some reading and found that putting this skimmer diverter can help increase suction to the far skimmer. My question is should i leave the diverter open fully or close it half way? is it bad if i don't use the suction from the bottom drain? i am still pulling from the closer skimmer.

Richard320 · Jun 1, 2013

aviolentworld said:
i really have nothing to add except another question.

my far skimmer doesn't seem to pull in the water as fast as the closer one, i mean sometimes debris just floats by instead of getting sucked in(i understand that some pressure might be lost because of the longer distance). so i was doing some reading and found that putting this skimmer diverter can help increase suction to the far skimmer. My question is should i leave the diverter open fully or close it half way? is it bad if i don't use the suction from the bottom drain? i am still pulling from the closer skimmer.

I'm not understanding how your pool is plumbed. The two skimmers are on one line? Or both skimmers and the main drain are all on one line?

Actually, it doesn't matter. Just experiment to try and equalize the flow. If it turns out the diverter doesn't help, you're only out a few bucks.