I hate having to pump perfectly and expensive treated pool water to waste when vacuuming up fine debris that my sand filter won’t catch.
Does anyone know of an inline filter for fine debris that I can either put inline with the vacuum hose or the waste so I can pass filtered water back into the pool?
The sand filter should collect most of the very fine stuff (mine did when I had a pool). Maybe change the filter medium - glass is meant to be pretty good.
@Corona pointed me to this Company for this…
and I found they also do this…
which (being a bit anal about having things “right” 
) I’m temped to install. (as @Mark mentions)
Sadly its BS, the media is almost stationary during filtration and only moves during backwash which if done correctly is an expansion of the media more than anything else.
People take out dirty sticky sand and replace it with “new sand” which is probably at least 65 million years old. I went on a visit to a company a few years ago to see their proprietry cleaning facility. We viewed sand under their microscope and they asked us to guess which was the new and which was the old sand you could not really tell once it had been cleaned.
That said Drydens AFM glass is in a different league, the original filters down to 4-5 microns and the new AFM ng filters to 1 micron, finer again if you correctly use flocculent. AFM glass is self sterilising so bacteria dont colonise on its surface unlike sand which gets colonised, sticky with the bacteria’s polysaccaride gel. That then allows the sand grains to stick together, known as mud balling and channeling occurs as the clumping allows pathways through the filter which is one reason why fine stuff can pass through the filter. Cleaning the sand instead of replacing.
Following from my explanation above, if you use netskim bags around your skimmer baskets and then put a scrunched up cotton towel in the skimmer basket it will catch the very fine stuff, obviously this assumes you vacuum through your skimmer.
If I replaced the sand with Drydens AFM should I use the same volume as sand? I read one could use a smaller amount but for the sake of a few quid wouldn’t it be better to top it up to the same level. I suppose I just take the top of the filter vessel and scoop out the old sand?
Thanks for all the info 
There are some good videos on You-tube about how to change the medium in a sand filter - you need to keep the sand out of the pipes, so it’s not just a matter of scooping it out. 
Good question, I have always used as suggested 25% less (the sack size has altered since the early days so I forget exactly) I have a gauge ( turbidity ) and the clarity with less AFM hasn’t suffered using less as suggested. In German DIN standards, the highest in the world their commercial filters have a bed depth of 1200mm. As I prefer energy saving it works with less and glass is less dense than sand hence the reason for the reduction.
I use a wet vac mostly, suggest you wear gloves as the filthy sand could be considered a bio hazard. I also wear a mask as I do not want to breath in any of the bacteria that may be present, as I did this for a living I was exposed to this risk too frequently not to.
Remember when re-filling, half fill the filter with water so you are not dropping media onto the laterals. Backwash thoroughly for longer than normal to ensure all dust is rinsed away.
Just going back to your previous point, if you add too much AFM as its less dense therefore you may end up backwashing some of it away, depends on your filter. Taller filters are better than the round ones.
Could you not just chuck a couple of litres of industrial strength javel into the skimmer just before you open the filter to take the sand out?
In a field study performed by the Clean Washington Center, researchers replaced 1,950 pounds of sand from three high-rate filters with recycled glass and analyzed the results for approximately nine months. Here’s what they found:
Less water: The average duration of backwashing (in minutes) was 2:34 compared to 3:21 for sand. That’s equates to a 23-percent reduction in water. The improved performance can be attributed to glass’ lower density, with approximately 20 percent less volume by weight than sand. The lighter material floats more easily, the study noted, allowing it to fluidize quicker, reducing backwash runtimes.
Yes all true. Its not just clearer water for esthetics, its removing a lot more dirt, bacteria etc, then there is less for the chlorine to react with, the chlorine lasts longer/reduction in use. I wouldnt reduce the running time but I would adjust the flow via the pump speed for greater savings.
I have been involved with the Clean Washington Center on and off since the early 90’s as we did most of the glass recycling technology and research in the UK and US and they do excellent studies.
The huge aquarium at Nausicaa in Boulogne uses AFM and they ran similar results but the couldnt be published because an opperative messed up towards the end of the test. The excellent IFTS in France ran extensive testing on AFM (earlier version not the ng version) with great results.
I had been plugging the vacuum line directly into the port under the skimmer basket, but I do have a top hat/skimmer plate which I’ll try using your tea towel method.
Looks like glass media will be the way to go after the season ends.
I’m pressing that you don’t need to check the laterals to use glass instead of sand?
Thanks again.
Fluffy towelling, just nick one of your wifes best towels. 
As long as the laterals are in good condition, you’ll cover them wit grade 2 AFM and Grade 1 above that for the bulk of the filter.
That seems to be the wrong way round. Less volume with the same weight means it’s density is higher, not lower. I think they probably meant 20% more volume by weight. Or maybe they meant 20% less weight by volume.
Silica sand has a density of around 2.68kg per m2, glass is 2.5, glass does not pack as tightly as silicone sand by around 20-22% depending on the grading scale size of the sand and if it has been acid washed.
Most sand used for white flint and green glass is acid washed to remove iron deposits.
Drydens own data sheet states
AFM® has a 15 % lower density than sand: e.g. if your filter takes 1,000 kg of sand it will only require: 1,000 x 0.85 = 850 kg of AFM®.
This corresponds to AFM having 15% less weight for the same volume as sand, not less volume for the same weight.