That is dead algae and some dirt from the air. The reason it collects in the same spot is that is the lowest spot(s) in the pool. Once the water is still it settles out of the water and ends up there. The down side of a sand filter is the fact it does not always catch the finer stuff in the water Until you can "catch" all of the stuff and get it up and out of the pool it will settle out of the water waiting for your filter to catch it or you vacuuming it out of the pool by waste (which you have been trying to do with not much luck ).
Have you added any DE to your sand?
Okay so who put the sand in your filter? Any idea what kind of sand was used???
While feedback indicates it should be fine, you're not the first person this year to have a problem. See Changing sand. I don't know if in the other person's case they had a problem with the laterals or something, just noting the thread so you can compare situations.I replaced the sand last year mid way through the way. I bought pool sand from Ocean State Job Lot. It was this sand
Pat is thinking what I am...............could there be something that is allowing stuff from the sand to come out into the water/pool? With the pump off and not mess to pump on = mess............
I can say that when I added DE to my sand filter it cleared out all my dead algae haze in less then 8 hours. The difference it made in the efficiency in my filter was night and day. You add a bit at a time directly into your skimmer until the psi on the pump goes up just 1. In my case I just needed to add 1 cup. Also if your filter is actually broken(usually a broken lateral) when you add the DE it will shoot straight out back into the pool almost immediately and will be obvious. You will then know for a fact if your pump is broken or not.
This may be the case. I did carefully inspect each of the laterals last year when we changed the sand. No signs of any cracks, etc. I even carefully flexed each of them to see if a stress crack or something was happening, like under pressure. I didn't see any sign of this.
Did your dead algea look similar to my photo's above? I really can't tell what it is, but pool sand doesn't seem to "poof" like a dust bunny like whatever this is. DE might be the way to do.
Is DE the same as DE filter aid in the link below?
This just happened to me the other day ( have a thread) My pool was hazy and so I slammed the pool overnight. The next day I could see on the steps and the pool floor that I had a very fine dust which went poof(I am assuming was dead algae, could have just been dust). I ran my filter nonstop, threw my robot in and let it run all day. I picked up some of that DE that afternoon and put in a cup full in the filter and the next day my pool looked clearer then it ever had. I did an overnight FC loss test which shows that all the algae is dead. (measured FC and CC after the sun goes down and first thing in the morning the next day FC was same with no CC)
I think that’s basically the same stuff DE should just be DE. I got mine from Lowe’s. Says on the site it’s for DE and sand filters.
I'm at a loss, so I'm going to try it. I had my local pool store do a water test(just for giggles I have a kit, I wanted to see how far they differ) and asked them about this. They know I've been in a couple of times, and I've spent some money with them. They gave me probably 2lbs, I added about 16/17 OZ of DE for my filter pressure to rise 1psi, and I'll try it.
My CC was up to 1 this morning. But my FC didn't drop between yesterday and today. Which is very strange for me. I need to find the clips for my robot bag, and I'll throw it in for the afternoon.
The only thing I would be worried about is that CC being at 1. Did you get that with the test kit or from the pool store? Running the robot around will kick all the stuff up that it can’t remove and the DE in the filter should help it clear it quickly, as opposed to days or weeks unless your filter is really messed up. It can’t hurt anything to add it unless you add to much. Just remember to add more whenever you backwash.
Both. I know pool stores are notoriously inaccurate, but I was there anyway so I had them run it.
But, after adding DE to the skimmer yesterday, and still running the pump for the SLAM I'm not getting DE in the pool. This tells me I have a filtering issue. The sand filter laterals have been checked. I will go ahead and take the filter apart again and carefully check each of them myself.
Before I tear this apart again, Is there anything else besides the laterals that could be allow debris to escape through the filter?
If your not getting DE in the pool, then your filter should not be broken, and the DE will help the filter remove all that stuff. The sand might need to be cleaned though. If it’s broken, I’m not sure, I think some filters have this tube on the top and if it’s not right it could shoot stuff into the pool... but you should research your particular filter first.
Lol! I was hoping I hadn’t mistyped something and steered you wrong!
How old is the filter? I wonder if the gasket called a spider gasket is needing replace?