DE filter- gray/tan dirt (sand) at bottom of the pool

[Fjvaughn]

I started off with a previous post thinking I had DE at the bottom of my pool. Now I don't believe it was.

Pentair Quad DE 60 leaking

This year’s opening started off with a bang. The liner fell due to a warm winter, which I fixed, but there’s wrinkles at the bottom that are fairly severe I still have to attend to. Also, it appears that DE is seeping back into my pool. I’ve tightened up everything and I don’t see what’s...

www.troublefreepool.com

Folks in here suggested mustard algae, as did the guys who built my pool. I did both the SLAM process and the algaecide method ( I know, go ahead and yell). The suspected "algae" never turned brown as it was supposed to. Nevertheless, I vacuumed to waste and then used the robot. I still go out every day and see collections of this dirt in great quantities trapped in corners and wrinkles. Today after my robot picked it up, I did a bit more analysis. Attached is a picture. It's the consistency of beach sand (coarse).Shown is several ounces in a coffee cup.

The fatalist in me is now suspecting an underground pipe leak letting this material in. I'm contemplating having someone run a camera down the pipes.
Pool is crystal clear (never cloudy) and the residue just sits on the bottom. I don't see anything too coarse in the skimmer or skimmer socks. Here's some chemistry from today for the record.:

FC- 4
TC- 4
CC- 0
pH- 8.1
Hardness- 163
Alkalinity- 104
CYA- 33
Copper- .4 (Dang algaecide, lesson learned)
Phosphates- 1230
Salt- 3300

 

[YippeeSkippy]

Any chance your filter grids have a small tear in one (or more) and letting DE return to the pool? Have you been able to inspect?

 

[Fjvaughn]

My filter is a hybrid. It uses DE but has 4 cylindrical cartridges. I’ve taken them out and inspected them thoroughly but I didn’t see anything. It may be possible. Water is not dirty overall. It’s clear with sediment at bottom.

 

[fmblizz]

Certainly seems like a crack in one of your pipes most likely a return line otherwise the debris/sand would get captured in your filter.. I would think you would notice a water loss constantly.. DE would not be visible especially in a pool the size of yours. Cap off your pool lines in the pool one at a time and watch the water level if possible at the pump over the course of a couple hours. My money is on a cracked return line. good luck