Optimizing skimmer operation

[Blackdirt Cowboy]

I’ve only been operating my new pool for about 2 weeks now. Every morning when I check the pool, the surface is clean, but lots of leaves have made their way to the bottom of the pool. I have no clue if that’s relatively normal or not, as this is my first pool I’ve ever owned.

My pool is set up with 2 skimmers, a split main drain, and six returns. The first thing I did was set the returns so they are pushing the water in a counterclockwise direction. I have them all pointed to the right and relatively flat, not pointed toward the surface or the floor. I haven’t been able to verify a swirling motion with ping pong balls, but based on the way the surface debris is moving, the water is spinning.

My skimmers are set up with no float valve or equalizer valve. There are two outlets on the bottom of the skimmers, one connected to the pump and the other connected to the main drain. I currently have the trimmer plate on the main drain outlet completely shut.

At the equipment pad, I have three suction lines coming into the pump(ignoring the spa suction), one from each skimmer and one from the main drain. The pool builder had all the valves wide open when he started the pool up. He also wants me to run the pump 24/7 at 2070 RPM for the first few weeks.

I went and played with various setting of the valves this morning to try and optimize flow through the skimmers in order to pull more of the leaves into the skimmers before they have a chance to sink to the bottom. I closed off both skimmer valves with the main drain valve wide open. Then I started closing down the main drain valve slowly until the pump started struggling and slightly cavitating. Next, I opened it back ever so slowly until I reached the point where the pump was pulling only from the main drain and was running smoothly. Then I opened both skimmer valves wide open. In my mind, with the valves in this position, the skimmers are pulling as much as they can, and the main drain is open enough that if the water level falls below the skimmers, the main drain will flow enough water to not starve the pump. Here is a pic of how the valves ended up being set.



The main drain valve is about 25% open and the skimmer valves are 100% open. Is it safe to operate the pool in this manner? When I have the main drain completely shut and both skimmers open, they actually create a vortex over the skimmer basket. With the valves set in this configuration, there is no vortex, but is pulling in water noticeably stronger than with the main drain completely open. I just want to make sure I’m not going to damage anything. Thoughts?

 

[TinFoilHat]

You're fine. You have it set up correctly.

 

[proavia]

Without the skimmer diverter/float valves in place, if the water level gets below the skimmer throat the pump will suck air. Be sure your autofill is working properly and that the skimmer diverter/float valves (if used) are functioning as intended.

Having the main drain open 10%-20% should provide sufficient skimming when skimmer valves are open 100%. You can also balance the skimmers by adjusting their valves to provide the same skimming to each.

Once you have added salt and get the SWG running (usually at least one month after plaster), lower the pump rpm until the SWG flow switch triggers a no-flow condition. Increase the pump rpm until the no-flow light goes out. Then add 200 rpm to that number to set the minimum rpm to run at. Adding that 200 rpm will account for the filter getting dirty.

 

[Jimrahbe]

There are two outlets on the bottom of the skimmers, one connected to the pump and the other connected to the main drain.

BC,

The above statement is doubtful. When the main drain is plumbed back to the equipment pad, it is not plumbed into the bottom of the skimmers at all..

In theory, the hole in the bottom of your skimmer that is away from the pool, is connected back to your equipment pad. The hole that is closest to the pool is plugged.. If there is no plug in the top of the skimmer, then the hole is plugged under the bottom of the skimmer.

The idea that your main drain will keep your pump running if the water falls below the skimmers is just not true, if you do not have a floating diverter valve.

I'd run the main drain about 10% open, just to keep water flowing through it, as it is not really needed...

Not sure it is really worth the effort, but you can adjust the two skimmer valves so that you have about the same suction at both skimmers. The skimmer that is close to the equipment pad will have a lot more suction than the one further away, unless you adjust the two skimmer valves

How fast are you running your pump??? If you get a vortex, then I would assume way, way too fast..

Skimmers 'skim' because of the floating weir between the mouth of the skimmer and the skimmer basket. Do your skimmers have operating weir doors??

Thanks,

Jim R.

 

[Blackdirt Cowboy]

BC,

The above statement is doubtful. When the main drain is plumbed back to the equipment pad, it is not plumbed into the bottom of the skimmers at all..

In theory, the hole in the bottom of your skimmer that is away from the pool, is connected back to your equipment pad. The hole that is closest to the pool is plugged.. If there is no plug in the top of the skimmer, then the hole is plugged under the bottom of the skimmer.

The idea that your main drain will keep your pump running if the water falls below the skimmers is just not true, if you do not have a floating diverter valve.

I'd run the main drain about 10% open, just to keep water flowing through it, as it is not really needed...

Not sure it is really worth the effort, but you can adjust the two skimmer valves so that you have about the same suction at both skimmers. The skimmer that is close to the equipment pad will have a lot more suction than the one further away, unless you adjust the two skimmer valves

How fast are you running your pump??? If you get a vortex, then I would assume way, way too fast..

Skimmers 'skim' because of the floating weir between the mouth of the skimmer and the skimmer basket. Do your skimmers have operating weir doors??

Thanks,

Jim R.

Yes they both have operational weir doors. Currently I’m running the pump at 2070 RPM as per the pool builder. Like aquaholics suggested, I plan on slowing the pump down to the minimum required to keep the SWG running once we add salt and get it operational.

Sounds like I can close off the main drain a bit more. It also appears that it would be prudent to purchase a float valve for the skimmers to prevent air suction in the event that the water level ever drops below the skimmers. I am, of course, assuming that these are an optional add item and that they operate that way. Skimmers are Pentair Bermuda skimmers, for what it’s worth.