Gray sediment @ bottom of pool

[nicksd]

I have a gray fine powder at the bottom of my pool. (happened last year, every sense I put in baking soda to help my ph). Now when I vacumn the pool it comes right up goes threw the filter and into the spa. (I have my pool return going into the spa, spa overflows and puts water back into the pool) Now the spa gets full of this gray substance but the pool is nice and clean. Now what I do is just run the spa only threw the filter and it gets filtered out and goes away, both the spa and pool is nice and clean for a day or 2. 2 days later the same thing happends all of this gray substance goes right back into the pool I have to repeat the same process. Help Help.

[TSH Tech]

I'm going to take a guess, and say you have a cartridge filter? If so, that fine powder will never trap in the filter, it will literally pass right through it because cartridge filters only filter down to so many microns of particle size.

Here's what you do, at this step:

Now what I do is just run the spa only threw the filter and it gets filtered out and goes away, both the spa and pool is nice and clean for a day or 2. 2 days later the same thing happends all of this gray substance goes right back into the pool I have to repeat the same process.

Vacuum, filter or what ever it is you do to clear up the grey powder, shut your pump down, take apart and clean your filter with the garden hose out in the lawn or yard. You should start to see the grey powder diminish. Repeat the cleaning until its gone.
The only other way to remove fine silt from a pool that will not filter, is to vacuum the pool and let the water discharge out on the lawn or somewhere safe that water can flow out and away. Typically this is done with a portable pool pump on a dolly rig or if there is a waste/discharge feature built in to the pool equipment.