Sand Filter Question

Hi. I have a new customer that changed the sand in his filter by himself. I am sure that he got sand down the center "stand pipe". The first time that he backwashed, there was probably about 5 pounds of sand pumped out on the lawn. I don't think he broke/cracked any laterals as there has not been any sand coming into the pool. At this point, it takes the pump a long time to prime and it seems that it "working hard" to circulate the water through the filter. Could this be a result of him getting sand down the stand pipe? Also, if the pump is having a hard time pushing the water through the filter, could I possibly see some air bubbles forming in the lid of the pump? There is plenty of water in the pool and the pump lid does not leak when you shut the power off.

Thanks for your input!

Matt

Replies

Norman Tyree June 17, 2011 at 2:50pm

Norman Tyree said:

Lots of free advice but no real answer.

People go to pool shops and are sold sand, easy to do they are told but then what did they do? I had one case years ago where the handle on the MPV was put on the wrong way and the laterals had acted as a filter and blocked.

But still no answer to your problem remove all sand and check again to see the laterals are not broken. BUT BE CARE FULL MAKE SURE YOU SHOCK DOSE ANY FILTER BEFORE YOU START WORKING ON OLD SAND OR MEDIA BECAUSE SOME YEARS AGO IN CANADA A GUY DID A SAND CHANGE AND HE POKED HIS EAR AND WITHIN 48 HOURS HE HAD AN INFECTION THAT ENDED UP IN HIS BRAIN. AS A RULE I USE A COMMON HOUSE BLEACH AND PUT IT INTO THE FILTER AS SOON AS I REMOVE THE VALVE.

Read and do this and you wont be at risk! www.poolquartz.co.nz
Norman Tyree June 17, 2011 at 2:48pm

Lots of free advice but no real answer.

People go to pool shops and are sold sand, easy to do they are told but then what did they do? I had one case years ago where the handle on the MPV was put on the wrong way and the laterals had acted as a filter and blocked.

But still no answer to your problem remove all sand and check again to see the laterals are not broken. BUT BE CARE FULL MAKE SURE YOU SHOCK DOSE ANY FILTER BEFORE YOU START WORKING ON OLD SAND OR MEDIA BECAUSE SOME YEARS AGO IN CANADA A GUY DID A SAND CHANGE AND HE POKED HIS EAR AND WITHIN 48 HOURS HE HAD AN INFECTION THAT ENDED UP IN HIS BRAIN. AS A RULE I USE A COMMON HOUSE BLEACH AND PUT IT INTO THE FILTER AS SOON AS I REMOVE THE VALVE.

Read and do this and you wont be at risk!
Lester Eric Brehm June 17, 2011 at 6:55am

With the pump running,pour water on the exposed suction pipe and fittings, when the water hits the leak you will see the air in the lint pot stop or slow down.Make sure the skimmer weirs are not stuck also.
Matt June 16, 2011 at 10:29pm

Hi, Rob. I will give your backwash technique a try. While the customer is cheap, they also don't have a clue about the pool. They just purchased the house in Nov. of 2010. The valves on the system are crappy slice valves like you would find in a self-contained spa. I have not seen any drips/leaks at the filter pad; nor do I hear any hissing/sucking/etc with the system on or off. I will definitely go over the valves and plumbing at the filter pad again, though. For some reason, my gut tells me that it's a filter problem - too much sand dumped in the stand pipe when he changed the sand out. Anyway, I appreciate the tips and will use them in my "detective work".

Thanks!

Matt
Rob Lane June 16, 2011 at 10:08pm

Backwash the tank three times for 5 min. each. This may clear out the laterals and the stand pipe. Allow the system to go to neutral each time, between backwashes. Add water to the pool.

How is the air getting in the system?? The leak is most likely between the centerline of the impeller and the skimmers / main drains. Is there a way to easially apply pressure to these suction pipes? In the past, I have valved the MD to off and put a 7' stand pipe in the skimmer. When you run water in the stand pipe from the garden hose, it applies 1-2 PSI to the system. If the leaks are above ground, the drips will be seen. This is done with the pump off. If you wish, turn the multiport to closed.

Is there a chance that the suction side valves are broken and not fully opening? I can break the valve stem on a Spears valve with a hard look. This would lead to cavatation.

Could the problem really be just a cheap customer?
Matt June 16, 2011 at 8:21pm

Hi, Haus. It is definitely the right grade of filter sand. The tank will bleed air without issue. I am going there tomorrow and will see what it does on recirc.

Thanks for the tip!

Matt
Haus Johann Miedler June 16, 2011 at 11:23am

Easy way to check if you have a problem with filter media is to set master valve to circulate and see if the problem is still there. Also check that the new sand was correct grade.check breather lines in filter.
Matt June 15, 2011 at 9:13pm

Hi, Bud. Thanks for your reply. The pressure gauge runs right around 20 psi with the filter clean. I will take the top off of the filter and make sure that he has some free board. I lubed up the o-ring on the pump lid and do not hear it sucking nor does is shoot water out the sides when you turn off the power to the pump.

This is just the start of the problem. Even though there is little air in the pump basket area, there is enough down stream (after the filter) that the Polaris booster pump cavitates from too much air in the system.

I figured fix one problem at a time and it may fix the next one down the line.....

There is nothing leaking/dripping/etc on the filter pad! After the system has reached full prime and has run for awhile, if you shut it down, you do not hear any air/pressure release from any of the plumbing on the pad.

Anyway, I will check how much sand he put in the housing and post a reply once I have done so.

Thanks, again, for your reply!

Matt
Bud Brinkley June 15, 2011 at 5:47pm

Does it have a pressure gauge? That would tell you a little better what is happening. I had a customer once who filled his filter all the way to the neck with sand. This left the filter with so little surface area that it plugged almost immediately with the exact symptoms you described. The air in the pump strainer is usually caused by a dry lid gasket or another leak upstream someplace which would also cause the pump priming problems. Let us know what you find out.