Air in Pump Basket, Leaky Pressure Valve, Cracked Filter Housing

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jeremy

jeremy

0
May 30, 2013
74
Oceanside, NY
Title says a lot, but I'm trying to determine if I have a suction-side air leak that's causing the air in the basket, or if the leaks on the filter side are causing air to get into the filter.

I checked yesterday (Sunday) morning and the pump had about 4-5 inches of air that wouldn't go away. The water level was below the top of the intake to the pump. Flow at the returns was very low. So I backwashed the filter and during that process the pump basket filled completely with water. Ran the filter for most of the day/evening on Sunday and the water level didn't drop dramatically in the basket.

Pump was off for about 10 hours and this morning, after the pump had been on for an hour or so, i noticed there was a bit more air than the day before - about an inch of air. Is it possible that the leaky pressure valve in the filter, or the leaky crack in the bottom of the filter caused air to get into the basket? Or does an increasing amount of air in the basket seem to indicate a suction-side leak?

Here is a brief video of the pump basket.

Additionally, there was sand at the bottom of the pool, and after brushing it to the main rains, it ended up coming back out of the returns. Not sure this is relevant, but thought worth mentioning.
 
You appear to have a couple things going on - a suction side air leak and a possible problem with your filter.
First your air bubbles ... most certainly air is getting-in from the suction side. Please check everything listed on the Pool School - Suction Side Air Leaks page. Take your time and be very critical. It literally takes the tiniest defect to allow air to get "pulled-in" to the system. If there was a problem past the pump, you would find water being pushed-out of something.

As for the sand, that is odd as I believe your filter is a DE filter and your pool is indoors. Any idea where the sand came from? It's definitely sand and not DE correct? Sand/dirt vacuumed-up should be retained by the filter/DE grids. Have you done any work to the filter lately other than the backwash? I'm wondering if the filter manifold may have been moved or manipulated in any way to compromise the flow of water through the filter. Also, what type of filter valve do you have (multiport or pump style)? Perhaps there's an underlying issue there with a spider gasket or pump seal.

We'll look for your reply and see if as a group we can help get your issues resolved.
 
Regarding the filter, is it worth investigating and repairing an internal issue when the housing has a crack and is leaking water? Sounds like I'll need to replace it one way or the other.

Currently I have a multi port valve with a spider gasket that I replaced within the last year. Since I'm only plumbed for filter and backwash, I was planning to replace that mpv with a jandy never lube backwash valve when I replace the filter.

It's hard to be 100% what's in the pool, but it looks and feels like sand. The pool deck is made of paver stones with a very hard joint locking sand, but still some sand has worked its way out. I assume that's where it would come from.

We installed the vsp pump back in October to replace a single speed pump that was failing. They had to do a little extra plumbing to compensate for the new pumps additional height, and introduced two 90 degree bends just before the intake. I can check there, and at the union first. The lid and plugs are tight.
 
Yes, I would definitely pursue everything on the link above in search for any areas where air could get sucked-in to the plumbing from the pool's side skimmer to the pump strainer basket. Your pump is new, so that should not be an issue, but I would check the drain plug on the pump as well. Many of them have a small O-ring around that drain plug that have been known to go bad.

While your cracked filter housing could possibly allow air into the system when the pump is off, it is unlikely that it would be the culprit while running. With that much outward pressure from the pump, water should be coming-out of the filter, not letting air in. That would only happen once the system was shut-down. With the system off, it could allow air in, thereby allowing water (and DE) to possibly travel backwards towards the pool. As for repairing the cracked housing, that is questionable as well. So much would depend on the location/size of the crack and if you could apply a suitable product to adhere well enough. Replacing certainly would be ideal.
 
I had the guy who installed the pump stop by today to give me his take on the air in the basket. Bearing in mind that the water level wasnt THAT low, but there was a lot of churning and sloshing, he thinks that the issue lies with the filter. He said that since when i backwashed the pump filled all the way to the top, but on filter mode, the water level has dropped, it must be the filter causing it. Does that make any sense?

What is the explanation for the pump basket filling 99% when on backwash for a total of only 3-4 minutes?
 
Not so sure about his theory. We know a suction-side air leak will allow air in, not only to the pump strainer basket, but eventually to the filter housing (rising to the top inside) increasing pressure dramatically. I suppose it's possible that when the filter was switched to backwash, overall pressure increased a bit possibly contributing to some back-pressure helping the pump's strainer basket retain water. But as soon as it was switched back to filter mode, water "pull" (flow) increased and the strainer basket level dropped again. Some other things to consider that we should know:
1. Have you noticed any odd changes in your pressure gauge during these events?
2. Do you get lots of air released when opening the air relief valve (with pump on)?
3. When was the last time your DE grids (manifold/fingers) were removed and thoroughly cleaned?
We have to remember that when the pump is on, no air can enter at the filter housing - that pressure would push water out first. So any air entering has to be from the suction side while the system is on. The only time air would enter at the housing (pressure side) is when the system is off, but you would probably also notice water flowing backwards at that point.
 
It's been at least a year since the grids were removed and cleaned, however I recently opened the tank and hosed them down as thoroughly as I could before back washing.

Keep in mind this is an indoor pool, and over the last year has been covered and rarely used, so it's shouldn't get very dirty.

In the end, the crack on the housing which leaks about a drop/second, and which begins at the inlet threads, worries me enough that I'm going to replace the filter and mpv and go from there. We inherited this 7 year old equipment when we bought the house, and I'm not too certain of the maintenance schedule they followed. I'd rather start fresh at this point and at the same time leave no doubt about the auction side leak, if any. The installer will have a hard time convincing me there isn't one after they put in a new filter...

I'll update this thread when that gets done, hopefully soon.
 
We had the new filter and mpv installed this past Friday. At first the pump had some air in it and then filled up about 95%. I assumed everything was good at that point and proceeded to brush the pool. A little while later I noticed the water level had dropped more than an inch in the pool and the skimmers were sucking mostly air!

Apparently the brush created a hole in the liner. Luckily I had the pool guys nearby and after losing a few hundred gallons at least, they patched the hole.

Anyhow, after a day the pool water level hasn't changed even a millimeter and the pump basket is full of water except for a bubble the size of a dime. I'll keep an eye on it later and see if any air gets into the pump basket when it's off.

I think we're finally good to go. Now if I can just figure out how to get rid of the thin layer of DE that is lining the pool (from the broken/old filter). I have gotten out most of it by vacuuming, but if I move any more than an a foot/minute, it stirs up a cloud of DE and then I need to wait for it to settle and vacuum more. Is there a trick to this??
 
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