Pool filter sand facts !

I have found that when my sand pool filter stop filtering its not because the sand has worn. After learning the hard way I decided to do the root cause analysis. I took a sample of the sand out of my filter and a sample out of a new bag of sand and compared them. To my amazement there was no difference in size or corner rounding so basically they were an exact match with 10 yr old sand. I tested them under a microscope and through sizing screens. This blasted the MYTH of the sand wearing out!

I had a neighbor that had a problem with his after 8 years and he just added 1 bag of new and then his worked perfectly. I asked myself what could have contributed to his success of still working perfectly 4 years and going now. Bang it hit me ! when I had taken the multi port valve off I found paths in the sand like canyons leading to the edge where the water was bypassing the filtering process to some unknown percent. Knowing this I just poked a piece of flat wood trim around then revealed it and it works perfectly with the 10 year old sand. So root cause was the water finding the path of least resistance by going around the sand and not through it. Follow these instructions and if it doesn't work I will come eat your sand !

You right that it is a common myth that pool sand gets 'worn out' over time. Of course, this myth is perpetuated by pool stores who want to make money by selling you new sand! And, you are also right that sand can get channeled inside the filter. Doing just what you did --- opening it up and stirring it around ---- is a fix.

Also, sometimes a filter can get low on sand and just need to be topped off. This is especially true when a sand filter is paired with a too powerful pump. If the pump is too big, it just pushes debris through the filter without filtering it and it can also push sand through at the same time.

Thank you for your post and welcome to the Pool Forum!

i'm new, so i could very well be wrong, but this is what i *think* i understand from my reading: i should run a "backwash" cycle until the water in the viewing-tube thing is clear, which "un-compacts" the sand and washes it out. then run a "rinse" cycle, which re-compacts and re-levels the sand, making it a nice strong filter media again. did i understand this concept correctly? tia!

Yep! Backwashing for my pool typically takes a minute and a half or so and then I rinse for about 15-20 seconds.