Air in pump basket

[glintontx]

Okay, so I have two problems that I am wondering if they are connected to each other. First, when start up my main pump, I see quite a bit of air rushing in to the pump basket from the suction side pipe. It only occurs at startup and it occurs immediately after I turn on the pump but the air goes away quickly. Every once in a while I see a bubble or two come in to the basket after the pump is already on. However, the pump doesn't have any problems with priming.

The other problem i have is some DE getting in to the pool. At first I thought it was the grids (I have a Pentair 48 DE filter) and so I replaced almost all of the grids (one was replaced about 6 mos ago). However, the sand is still somehow getting in to the pool. Could the air coming in to the filter be the culprit?

All my O rings are new and lubed. Not really sure where to go from here.

Thanks in advance for any advice.

 

[Texas Splash]

Getting air in the pump basket only when the system is down might imply that you may have a tiny air leak or compromise somewhere on the pressure side. Water might flow backwards a bit emptying the suction line. And since you see no air bubbles when running the system normally, it would tend to eliminate the suction line as the air leak source. Add to that a recent problem with your DE filter, and it would make sense to make the filter housing your first target. Still, it would be good to check both suction and pressure sides for any possible air leaks. Always rule-out the pump basket O-ring as well.

Generally, when we have a new problem, we go back to what we worked on last. While you replaced most of the grids, perhaps there's still one odd-ball in there allowing DE to get by into the pool. Same could be said with the manifold or fingers if one is damaged or didn't fit together quite right after maintenance. Is there any visible sign of water leakage "after" the pump and/or around the filter housing? Housing seal or even the pressure gauge might be a good target. Also, do you have a multiport valve or pump-type selector valve for your filter?

Do you have any other equipment in your set-up that you might want to add to your signature (i.e. pump type/HP/speed, SWG, heater, spa, etc)? Any check valves installed? Any of these items could also play a part in your situation if installed. With a little more info we may be able to help give you some other course of action to pursue.