Solution to challenges with Venturi Skimmers

[scott.lopez]

We just finished building our pool in April and had two venturi skimmers by A&A installed. Before getting started, I will say that I am very pleased with the skimmers, even at speeds as slow as 25 GPM, these skimmers continue to pull a large volume of water, keeping the pools surface clean.

One issue that we have had with the skimmers is that the bags fill up with air. This occurs because our equipment pad sits above the water level in the pool.



In this picture you can see the skimmer bag floating up. This in turn seems to cause the performance of the skimmer to be reduced.

I tried rocks and other simple items hoping the issue would be resolved. Unfortunately, with rocks and similar items, the air under the skimmer bag was still forced up as seen in the picture. The rocks also reduced the amount of surface area available at the bottom of the skimmer bag, thus reducing performance.

I tried two different approaches, I'm using each approach in a different skimmer (we have 2).

The first approach was to create a plus sign using 1/2" PVC 4 way coupler, 4 short (1 1/8") 1/2" PVC, and 4 1/2" caps, this contraption was filled with sand to give it weight.



This approach works really well in most cases. For the skimmer that was farthest from the pumps, I left this version in place.

For the skimmer closest to the pump, this version did not have enough weight and floated to the top. So I extended on the above version and included four vertical 3" pipes to add weight yet still not reduce the surface area at the bottom. Filled the new version with BB's from wal-mart to give it extra weight. Seems to work very well.



below is a picture of the device installed in the skimmer:




This solution has made quite a difference. The amount of water being pulled and sucked down is much greater.

Hopefully someone finds this to be helpful.

 

[kimkats]

Thanks for sharing this awesome idea! Good thinking outside the box!

Kim

 

[YippeeSkippy]

Well done!

 

[Pool Clown]

The air developing in your system isn't because your system is above water level, but rather from the ozone unit, or from a partial drain back when the system is off (shouldn't be happening), and subsequent purge when the pump starts.

Question: If you get rid of the air bubble in the skimmer basket bag, will it accumulate again later in the day (same run cycle)? If so, it could be some of the ozone gas exiting through the return line accumulating in the skimmer basket. If not, then it would suggest a partial drain down overnight, and then purges the trapped air from the system when the pump starts the next day, giving you the bubble in the skimmer bag.

The venturi skimmer directs return water through a jet aimed toward the pool to create the draw through the skimmer. To create a bubble in the skimmer basket there would have to be a lot of air going through the line. Small bubbles would just pass through the jet and on into the pool. Its the large amount of air that is making it's way to the skimmer bag.

Bottom line?
If it is "air", this isn't normal, and should be addressed by the pool builder.
If it is Ozone gas doing this, there may not be a fix, that gas needs to be present in the return line to do it's sanitizing job. Perhaps loose the mesh bags, and get finer mesh baskets?

 

[scott.lopez]

The pool equipment is above the pool level, so when the pumps turn off the water drains back into the pool. The pump then reprimes and this is when the air is pushed through. Am I understanding you correctly to say that this isn't normal?

Thanks

 

[mas985]

A pump should never lose prime when shut off! That means you have an air leak somewhere. Usually on the suction side of the pump.

Also, the return plumbing should not lose prime either unless you have a VRV installed for solar.

 

[scott.lopez]

I will have the pool builder take a look. Thanks

 

[scott.lopez]

We do have ozone on the pool, but I can actually hear the return pipes draining. I think there is a different issue from ozone. I contacted the pool company to take a look.

 

[mas985]

Do you have solar?

 

[scott.lopez]

no solar.

 

[mas985]

Ok so you shouldn't be getting air in the system at all. There must be a leak somewhere.

 

[scott.lopez]

learned something new, pool company agrees. Sending someone out tomorrow.

Thanks everyone.

 

[Pool Clown]

Depending on the particular manufacturer of Ozone unit, it (the Ozone) can be drawn in through the suction side OR the return side. What is the manufacturer of Ozone unit you have?

 

[scott.lopez]

we have a del ozone, we also have the MDV (mixing vessel that should get rid of a lot of the bubbles.

 

[Pool Clown]

we have a del ozone, we also have the MDV (mixing vessel that should get rid of a lot of the bubbles.

Therefore, you should be getting no air in the skimmer. The degassing chamber should be inadvertently bleeding off any "air" as well. If you have the Solar Eclipse, that is the same unit we sell and service. We are having some issues with the float in the top chamber of the degasser. For some reason, the float valve is malfunctioning, and not allowing the gas to be bled off. Therefore the gas is passing through the plumbing and on to the pool.

 

[scott.lopez]

pool guy came by, said he sees this sometimes. I pushed him a bit and explained that it wasn't normal and that the skimmers can't function properly with air filling up the skimmer bags. He agreed and they are going to send someone from the construction team to take a look.

Thanks for the advice!

 

[Pool Clown]

Don't let them tell you "that's just the way they run".

Your system is not running "as intended".

 

[scott.lopez]

I have isolated the air entering the system to the Del Ozone. I can hear air entering into the chamber after the equipment is turned off. This in turn drains the ozone system and all of the pipes. Should the entire MDV drain and allow air into the pipes. Pool company is saying that it's normal. I'm inclined to disagree. Perhaps some residual air from the ozone should enter but it shouldn't drain everything. Based on this information am I misinformed or should they be resealing something. Thanks

 

[Pool Clown]

I don't believe that it should be letting air in when the pump shuts off. You may have a problem with the unit internally. Do you have the direct number to Del Ozone? You should give them a call and describe what is happening.

Contact Del Ozone

Either Dana Nelson or Jim Brown. Both guys are pretty sharp on the Solar Eclipse.

 

[scott.lopez]

They are closed for the holiday break. If we don't reach an agreement today I will be calling them next Tuesday. And yes, the Del Ozone people are very helpful.

Thanks