70gpm pump with 60gpm Filter

[Richard Gray]

I have a new Pump and Filter that where sized by the pool store and installed by me. I am having issues with filter sand (90% sure it is filter sand) in the bottom of the pool. I have vaced it to waste a few times but it keeps coming back. I opened the filter up today to check the Freeport level thinking mabe I overfilled it and the sand was bowel shaped with the sand level at the center around the riser stem at about 16" and the sides where about 8" below the rim. The book calls for 10.25". there was sand/debris trapped around the top of the stem where it mates to the bottom of the multiport. this area was clean when I put it together last week. I have a Aqua Gene that has a slot for the return water so I have not been able to do the sock trick to confirm the source of the sand is indeed from the filter.

I have only two lines on the suction side of the pump that average about 38' of head and the performance graph of the Pentair 1hp single speed Superflow pump shows a GPM of about 70 at this head. This is 10 GPM greater than the TA-60 Filter they sold me. Could this be causing the filter to force sand back into the pool?
Help.

sure looks like the 3/4 hp would have been a good fit.
I paid them a $85.00 service fee to come and look at the pool before they proposed this new equiptment.

 

[cheddar85]

It's possible, but let me ask a couple of questions first before we assume that. They may help me or someone else give more accurate answers.

1. Have you inspected the laterals? Meaning, take all the sand out, and really look at each one carefully. Make sure there's no cracks anywhere, including the riser.

2. Are you sure the sand is the right type? For most filters, it should be #20 silica sand.

What you said about sand being trapped where the riser meets the multiport could indicate it's not sealing correctly.

Sorry I can't be more help, but maybe with more experience will be along soon. They can probably provide better insight into what's going on.

 

[Richard Gray]

John,
I did a close inspection of the laterials and the riser when i installed it last week. The sand is pool filter sand I got from the pool store. BTW I put in 325# as per the book.

 

[Richard Gray]

OK, I got a good look at this so called sand and is clearly NOT sand. same color as my filter sand but it dissipates when moved. It is Very Very fine. It smears onto the plastic steps looking like a skid mark in your shorts :? but brushes right off. So now I am at a loos as to what it is coming from. The water is just a few days old. the pool was filled on the 16th, shocked it on the 17th and held to only 1PPM loss over night. Hasn't been under 10.5 since. This stuff has been sitting along the vinal seems, around the perimeter of the hopper and is even resting in the dimples of the plastic steps. It does seam to be getting a little less each time I vac. I have been running the vac to waste every other day. how long should I rinse the filter after? Maybe that is where I am going wrong.
Stats are:
FC14
TC14
PH 7.2 (working on dropping the TA thanks to the pool store)
CA 40
TA95
CYA50 (best guess, newly added) working to get 70
Borates 0 (I plan to add this as soon as the pool is stable)
salt 3600
temp 68 and climbing with solar