Robotic Pool Vacuum Cleaning Great but Leaves Fine Dust Behind?

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Petar K

New member
Hey,

I’ve been using a robotic pool vacuum for a few weeks now and overall it does a great job. It picks up leaves and larger debris no problem. But I’ve noticed that there’s still a layer of fine dust that settles back onto the bottom the next day.

Is this just something robotic vacuums can’t get, or do I need a finer filter inside the vacuum? I use the Eagle Ray Digital Water Testing Kit regularly and all my water levels are where they should be, so I don’t think it’s a chemistry issue.

Just wondering if anyone else has had the same problem and found a fix. Thanks in advance.
 
Yep, I’ve noticed the same thing with mine. It does a great job on leaves and bigger stuff, but that fine dust always seems to settle back down. I switched to a finer filter and it helped a lot—not perfect, but way better. I also give the pool a quick brush before running the robot and that seems to help it catch more of the smaller stuff. Definitely worth a try.
 
Interesting, so starting with alkalinity might actually help pH stay more stable? I’ve been doing the opposite, just going straight for the pH increaser. Might have to switch it up and see if that makes a difference. Anyone else notice that works better?
 
Petar K said:
Hey,

I’ve been using a robotic pool vacuum for a few weeks now and overall it does a great job. It picks up leaves and larger debris no problem. But I’ve noticed that there’s still a layer of fine dust that settles back onto the bottom the next day.

Is this just something robotic vacuums can’t get, or do I need a finer filter inside the vacuum? I use the Eagle Ray Digital Water Testing Kit regularly and all my water levels are where they should be, so I don’t think it’s a chemistry issue.

Just wondering if anyone else has had the same problem and found a fix. Thanks in advance.
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Totally get what you mean—mine does the same thing with fine dust. I added a finer filter and it made a noticeable difference. Also, I started brushing the pool before running the robot so the dust floats up and gets picked up easier. Not perfect, but much better overall.
 
I used to battle that ‘dust blanket’ every morning until I started skimming the surface for two minutes before sending in the robot. Feels like it vacuums in fast-forward now, and my pool sparkles by bedtime!
 
I ran into the same frustration with my robot, it looked spotless at first, but that super fine dust would creep back by the next morning. What finally made a difference for me was checking the circulation. If the return jets aren’t angled right, a lot of the light stuff just drifts around and settles again. I angled mine slightly downward and toward the middle so there’s a constant gentle movement, and it cut down on how much dust was left behind.

Another thing that helped was running the robot right after I brushed, but then letting the pump run a bit longer than usual afterward. That extra circulation gives the filter system a chance to grab what the robot misses.

It’s probably not that your vacuum is failing, it’s just that the dust is so light it takes a combo of good circulation plus cleaning to really get ahead of it.
 
I had the same issue for a while. My robotic pool vacuum does a great job on the big debris, but there's always that fine dust left at the bottom. I decided to switch to a finer filter and brush the pool a bit before using the vacuum. It definitely helped, although not perfect yet. If you're dealing with the same thing, maybe give that a try switching filters and brushing the pool beforehand made a noticeable difference for me!
 
Yep, that’s a pretty common thing with robotic vacuums, they’re awesome at picking up leaves and bigger debris, but that super fine dust can be tricky. A couple of things that helped me:

  1. Finer filter inside the robot – upgrading the mesh or filter bag can catch more of the tiny particles.
  2. Brushing or stirring the pool first – even a quick brush of the walls and floor helps lift the dust so the robot can suck it up.
  3. Extra pump circulation afterward – letting your pump run a little longer after the vacuum gives the filter system a chance to grab what the robot misses.
  4. Return jet adjustment – if your jets are angled to circulate water toward the center, it keeps light dust from settling right back.
It’s usually not a problem with the robot itself, just a matter of combining a finer filter, a bit of pre-clean prep, and good circulation. The water should stay clear most of the time if you keep up with these steps.
 
I’ve run into the same thing with my robot too, it’s like it cleans 95% of the pool but that really fine, almost dusty layer still shows up the next day. What worked for me was treating it as more of a “system” instead of expecting the robot alone to do everything.

I added a fine cartridge filter, which helped, but the bigger difference came from tweaking my routine. If I brush the floor and walls first, then let the robot run while the pump is circulating, it catches way more of the small particles. I also noticed that if my pump doesn’t run long enough afterward, the dust just drifts and settles again. Extending the run time by an extra hour or two really cut down on that problem.

So in my case, the fix wasn’t just a better filter, but combining brushing, robot cleaning, and giving the circulation system time to finish the job. Now I only see that dust layer every so often instead of daily.
 
I’ve had the same issue! My robot vacuum used to leave fine dust behind too. Switched to a finer filter and it worked much better! I also give the pool a quick brush before running the robot to help it catch the smaller debris.
 
I’ve dealt with that too, my robot does an amazing job with leaves and bigger stuff, but that fine dust always seemed to come back. What helped me most was a combo approach:
  1. Upgrade to a finer filter in the robot, makes a big difference for those tiny particles.
  2. Brush or stir the pool first so the dust floats up and the vacuum can grab it.
  3. Run the pump a bit longer afterward to make sure the filter system catches anything the robot missed.
  4. Check your return jets, angling them toward the center or downward keeps light dust from settling immediately.
It’s usually not the vacuum failing; it’s just that fine dust is super light and needs a bit of extra help from circulation and pre-cleaning. Combining these steps should leave your pool looking clear longer.
 
I’ve noticed the same thing with my robot vacuum. It handles leaves and bigger debris well, but that fine dust can be stubborn. What helped me was a mix of a few things: upgrading to a finer filter inside the vacuum, giving the pool a quick brush beforehand to lift the tiny particles, and letting the pump run a bit longer afterward so the filter can catch what the robot misses.

Also, adjusting the return jets to improve circulation keeps the light dust from just settling back down. It’s not a problem with the robot itself, fine dust just needs a little extra help to get fully cleared.
 
Yeah, I’ve noticed that too, the robot does a solid job on visible debris, but that super fine dust seems to just laugh at it. I found that running the robot right after brushing helps a bit, but the real game-changer for me was checking how full the filter basket was. If it’s even halfway clogged, suction drops just enough that it can’t grab the lighter stuff.

Now I rinse the filter basket before every run and give the pump an extra hour afterward. Between that and slightly angling the return jets down, my water’s been staying clear much longer. It’s still not perfect, but it’s the closest I’ve gotten to “spotless” without dragging out the manual vac.
 
I had the same issue for a while and thought my robot was just missing spots, but it turned out the dust was blowing right back out through the vent because the filter screen wasn’t sitting tight enough inside the unit. After I made sure it was sealed properly and rinsed the filter each time before running it, the difference was night and day.

Also, I started running the robot in the early morning instead of midday, seems like the stiller water helps it pick up more of that super fine layer before it floats off again. It’s not perfect, but the pool stays a lot clearer now between runs.
 
Same story here, my robot does a great job on the big stuff but that super fine dust always sneaks back in the next morning. I don’t think it’s a chemistry thing at all, just how light that debris is.

I ended up getting a fine mesh filter basket for the robot and that helped a ton. Also, brushing before running it makes a surprising difference. I usually let the pump run for a bit afterward too, just to let the filter handle what the robot misses. It’s not totally perfect, but now the water stays clear for days instead of going hazy overnight.
 
I’ve run into the same thing with my robot, it does a great job on the visible stuff, but that thin layer of dust always sneaks back overnight. In my case, it turned out to be a mix of really fine silt and pollen that the standard filter just couldn’t trap.

I switched to an ultra-fine filter basket and it helped a lot. I also started brushing lightly after the robot finishes instead of before, sounds backward, but it kicks up whatever the robot missed so the pump and filter can grab it while the system’s still circulating. Running the pump for an extra hour or so afterward usually clears it completely.

Honestly, I don’t think any robot gets 100% of the fine dust on its own, but with a tighter filter and good circulation, it’s as close as you can get to spotless.
 
Yeah, I’ve had the same issue with my robot, it handles leaves and debris great, but that super fine dust always seems to sneak back in overnight. I upgraded to an ultra-fine filter basket and that helped a lot.

One thing that made a big difference for me was checking circulation. If your return jets aren’t angled properly, that light dust just drifts and resettles. Try aiming them slightly downward and toward the middle of the pool. I also run the pump for an extra hour after the robot finishes so the filter system can catch anything it missed.

Fine dust is just tough for most robots to handle alone, but with a tighter filter and good circulation, you can get the pool looking clear again without much extra effort.
 
I’ve noticed that same thin dust layer too, drives me crazy after thinking the robot did a perfect job. What helped me was switching to one of those ultra-fine filters and giving the pool a light brush after the cleaning cycle instead of before. It stirs up the leftover dust just enough for the filter system to catch it while the pump’s still running.

Also, make sure the robot’s basket isn’t even slightly clogged, I didn’t realize how much suction I was losing until I started rinsing it every single run. Between that and running the pump an extra hour or two, my water’s been staying a lot clearer. Not spotless, but close enough that I don’t notice the dust anymore unless I’m really looking for it.
 
You’re not imagining it, that fine dust is kind of the weak spot for most robotic cleaners.

One thing I haven’t seen mentioned much is how fast the robot is moving. Some models zip along the floor, which is great for coverage but not ideal for ultra-fine silt. The brushes stir it up faster than the suction can grab it, so it ends up floating and settling again later. If your cleaner has a “floor only” or slower cycle, that’s usually better for dust than a full walls + floor program.

Another thing to check is where that dust is coming from. In my case it turned out to be windblown dirt and pollen dropping in overnight. The robot was cleaning it, but by the next day there was simply new dust. Once I started running the robot in the early morning and covering the pool overnight, the problem almost disappeared.

Also worth a quick test: after the robot finishes, don’t walk around the pool deck for a bit. Fine dust on the coping gets kicked back into the water surprisingly easily and sinks straight to the floor.

Short answer: it’s usually not a chemistry problem and not really a “broken robot” either. Fine dust needs a slower pass, a clean/finer filter, good circulation afterward, and sometimes just better timing. When all of those line up, that dusty layer pretty much stops showing up.
 
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