What are these big chunks of pieces in pump basket


Mod Squad
LifeTime Supporter
Jan 17, 2012
Evans, Georgia
I'm suspicious of the "pill" like shape.....too hard for me to imagine that anything in the lines would take on that shape rather than a curved shape.
My vote is for a manufactured product, either chlorine with CA+/CYA or those CYA pucks.

Maddie :flower:
Last edited:


Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
Houston, Texas
Easy enough to determine if it is stabilizer or chlorine sticks. Get a 5 gallon bucket and fill it with tap water. Crush up one of the large chunks and put it in the bucket of water. Stir the water with a stick. Test for chlorine. If there is no chlorine test for CYA.
I would also ask the pool company exactly what products they have been using in your pool. I do know its not plaster. The pebbles would have been mixed into the plaster before it was applied to the pool, and reputable plasterers cover all the pipes to make sure no plaster gets in. Its not gunnite either. Gunnite has a much rougher texture. Sidewalk chalk would have dissolved and it wouldn't be one color on the outside and a different color on the inside.
I also vote for someone chucking something into your pool.
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Silver Supporter
Dec 20, 2015
Arnold md.
Pool Size
Liquid Chlorine
I got smaller versions of these up to two years after my pool was finished. It eventually stopped but it was plaster inside the pipes that eventually came out of the pipes. It eventually stopped but it was determined to be plaster for me.
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Gold Supporter
Jul 9, 2019
Winnipeg, Manitoba
Pool Size
Liquid Chlorine
Those contain CL, right? Should be easy to rule out. But I can see these eroding down to a pill shape.

Active Ingredients:
  • Trichloro-s-triazinetrione 91.57%
  • Copper Sulfate pentahydrate 0.99%
  • Other Ingredients 7.44%
  • Available Chlorine 84%

My water tested positive for copper when we opened this spring and I had no idea how it could have gotten in there. Doing some internet detective work identified the source - those helpful all-in-one sticks. Thank goodness I flipped over to TFP while my copper was only 0.3 - just below the level where blonde hair faces a risk of turning green.

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Silver Supporter
Sep 29, 2018
Mesa, AZ
I totally agree that this "debris" is left over construction / plaster that settled in the pipe(s). That explains the color and shape. One side has the half moon curvature. Just took some time to break it loose and travel to the basket.

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Silver Supporter
Aug 28, 2012
Houston, TX
Ok, for some reason viewing pics on my phone, I thought the debris was in the skimmer baskets and not the pump basket...my error. If that is the case, then these are definitely plaster pieces...there's no way anything of that size could be sucked into the drains., then the pump basket.

The OP said she was vacuuming via skimmer [that would cause a suction to pull the debris thru pipes and into pump basket. Anything dumped into the pool or skimmer baskets by pool guy would not be transported into pump basket unless they vacuumed too....pucks don't break that easy and neither does gunite, but saturated plaster would,,,,my only reservation is the quantity of the debris...that's A LOT of residual material in the pipes...I had one or 2 chunks that finally ended up in my scupper pump basket...it was also the color of my pebble tec. Has the OP stated what color is the plaster? If the same or near color, that's the material...
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