Skimmer drain vs bottom return(s) - why not always 100% skimmer?

[wayner]

I looked in Pool School and didn't see anything on this topic, so here goes.

My pool has one skimmer return and two bottom returns. With a valve at the pump I can select how much of the return comes from either (1) skimmer, or (2) bottom drains. I believe most IG pools are similar to this.

Why would I not always have it set to have all of the return come from the skimmer so that the skimmer has maximum suction and is better able to collect debris from the pool's surface? Why would I want to use the bottom drains, other than a situation where I have reduce the water level below the skimmer? If not 100% skimmer then what is the optimal setting?

 

[mknauss]

We recommend you just open the main drain valve so there is flow. But that 90+% comes from the skimmer.

 

[Jimrahbe]

W,

Thousands of pools have no main drain, or a non-functioning main drain.. They are not really required..

I always suggest that you open the main drain about 5 or 10% and open the skimmers as close to 100% as you can get.

I have three pools.. One has a main drain, and the other two have no functioning main drain.. I can't tell any difference in how they operate.

Thanks,

Jim R.

 

[wayner]

Thanks - that makes sense but I never saw it written down. I used to have a Kreepy Krawly connected to the skimmer so with that I would adjust it so that the KK moved at a good speed and wouldn't get stuck.

 

[willygee]

Similar setup to yours...10% main drains the rest skimmer and vacuum port to Hayward Navigator.

 

[markayash]

If I could find a flat plate to cover my bottom drain i would. Don’t use it and it causes the robot to get stuck every once in a while.
Debated taking it to a 3D printing company and getting one made

 

[wayner]

If I could find a flat plate to cover my bottom drain i would. Don’t use it and it causes the robot to get stuck every once in a while.
Debated taking it to a 3D printing company and getting one made

Yes, my Dolphin robot gets stuck for a bit on my drains from time to time. But it is generally able to resolve the issue after a few minutes.