Help with Air Bubbles

[kappadoce]

OK, so I am getting the hang of maintaining a pool (my second season). I am trying to figure out the source of an air bubbles in my return jets.
I usually have the pool set to 75% main drain suction, 25% skimmer suction. 75% pool return, 25% spa return. When it is set up like this, air bubbles are coming out of the return. I changed the suction to 100% main drain suction, and this fixed the problem, no air bubbles. So, i read that it may be the pool water level and the skimmer sucks air if it is too low. I checked that and the water was about 1/2 up the skimmer opening, so I added water until it was 3/4 up the skimmer opening. This did not fix the problem, there are still air bubbles, so I am wondering what the issue can be.

Any guidance is greatly appreciated.

Also, if anyone has any tips on where i can order Polaris 3900 sport replacement parts for good prices, that would be helpful too!

 

[mas985]

75% main drain suction, 25% skimmer suction.

Why?

If anything, I would put the skimmer at 100% and the main drain at about 10%. MDs are not very useful and you are much better off getting debris off the surface before it sinks.

But on to the air problem.

What is the filter pressure under the following conditions (100% MD vs 100% Skimmer)?

Do you see any air in the pump basket with the valve set to 100% skimmer?

Does the skimmer weir swing freely?

Air usually comes from a pump basket lid leak so check the gasket and apply some pool lube to see if that helps.

 

[kappadoce]

OK, so sorry for the tardy response, had my second child in July and have been pretty occupied with that. Nevertheless, I have done some more diagnostics and have monitored the situation over that time.

*My beginner diagnosis: I believe I have a leak (underground or not) in the skimmer suction line.

When i wrote the initial post, I had always set my suction to be 75% main drain, 25% skimmer. It became apparent that I was getting air bubbles coming out of the returns, although the pump skimmer pot was full of water. I have replaced that o-ring and greased it anyway. I do not think that is the problem. Since I was getting air bubbles, I moved the suction to 100% main drain. This stopped all air bubbles coming out of the return, the skimmer pot was also full of water. However, over the last couple of weeks, I have noticed that my pool is losing water. Anywhere between 1/4" to 1/2" per day. I have added water 3 times since mid July. It was losing water even with the settings at 100% main drain suction. There is no visible leaks coming from any of the above ground plumbing. What is interesting is that when my pump shuts off, after being at 100% suction on main drain, the jandy valve that controls flow from main drain/ skimmer squirts out some water. I took that apart and noticed one of the little o-rings was deformed. I replaced those o-rings and greased, but it still does that when the pump shuts off. (Note - this jandy valve does not leak any water when pump is running). Regarding the filter pressure: when it is 100% main drain suction, presure is at 15%, which is the baseline and where it should be. when i have 50% main drain, 50% skimmer, pressure needle hops around 8% and 10%

Now, over the last week i have been paying specific attention to the water level. I started the week with the water being a little over 1/2 up the skimmer mouth. Within 5 days, the water level decreased to even with the skimmer opening (roughly 3-4 inches). The last 3 days, the water has not decreased and stayed level with the bottom of the skimmer opening. Whats more is that the skimmer reservoir is completely empty (note, the bottom of the skimmer reservoir is several inches deeper than the bottom of the skimmer opening). This is leading me to believe that the water is coming out of the skimmer plumbing, because the suction valve to the skimmer has been shut off. there are no visibile signs of this leak (wet ground or concrete or water seepage).

What is the expert's thoughts on the diagnosis, and what is the best course of action?

 

[mas985]

Regarding the filter pressure: when it is 100% main drain suction, presure is at 15%, which is the baseline and where it should be. when i have 50% main drain, 50% skimmer, pressure needle hops around 8% and 10%

First pressure is normally measured in PSI or kPa and not %. Is that what you meant or is this some sort of odd gauge?

I have noticed that my pool is losing water. Anywhere between 1/4" to 1/2" per day. I have added water 3 times since mid July.

That is not unusual for the summer. I loose over 2" per week when I have the pool cover off. However, 3" in 5 days is a bit excessive and could be a leak. But I would confirm with a bucket test to make sure you have a leak.

But if you are getting air in the pump basket with the skimmer line on and no air when it is is off, then there is most likely a leak in the skimmer line somewhere and it could be leak leaking water even if the valve shuts off the skimmer line to the pump (i.e. underground).

 

[kappadoce]

Hi mas985 -

Yes I meant PSI. I will try the bucket test to eliminate evaporation. However, since 4 days ago, the water level has not decreased and is staying even with the bottom of the skimmer opening, so I suspect that evaporation is not the issue.

If there is indeed a leak underground in the skimmer line, what is the best course of action?

 

[mas985]

Looking at your pictures again, I would first try to seal around the edge of the skimmer. That is a fairly common place for leaks to occur and since the level has stabilized, is probably the likely location.

 

[kappadoce]

Any particular product you would recommend as a sealer for this application? or do i just use silicone caulk?

 

[mas985]

I have used E-Z path before with some success. There might be other products too.

 

[kappadoce]

OK, so I have conducted another test, that further makes me believe that there is a leak in my suction skimmer line.

I had my pump equipment turned off. Keep in mind the pool water level is at the bottom of the skimmer wall opening. I filled the skimmer reservoir all the way with water and put the cover back on. I came back about 90 minutes later and the entire reservoir plus the visible bottom pipe were dry. Since the bottom of the skimmer reservoir is much deeper than the bottom of the skimmer wall opening, it must be leaking under ground. In addition the jandy valve that controls suction on skimmer/main drain is about 2 feet higher than ground level, so it did not leak out of there.

If it is an underground pipe issue (crack, loose joint, etc...) what is the best way to try and fix without digging everything up?

 

[mas985]

For underground pipes, your best bet is a leak detection company so you can find out exactly where the leak is and then repair it.