Filter won't clear dust

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Fed up with pools!

Filter won't clear dust

Postby Fed up with pools! » Sun 25 Apr, 2010 16:54

I have a below ground concrete pool and a sand filter. The whole thing is only three years old. A brown/green 'dust' precipitates out of the water and covers the bottom of the pool unless there is a lot of swimming activity whereupon it mixes into the water making it cloudy. If I try normal vacuuming the dust is so fine it passes straight through the filter and back into the pool turning the water cloudy again until it settles after about 48 hours. Once settled, the water above the 'dust' appears perfectly clear. I mainly uses CalHypo for shocking as well as leaving a couple of tri-clor tablets in the skimmer for 'maintenance'.
The only way I have to get rid of the dust is to vac to waste. This is difficult as the dust is so fine that it tends to disperse as I vac unless I vac very very slowly meaning to clear it I have to vac several times leaving it a day or so between vacs so that the dispersed dust can settle again. As I live on an island where there is no natural water, only collected rain water, this is unacceptable in the long run. My questions are obviously a) what is this 'dust' b) how to stop it occurring and c) is there any way of making the sand filter more effective in holding onto the particles rather than passing them through and back into the pool.
Please bear in mind that, again because of where I live, 'fancy' pool chemicals are not available, only those to adjust ph (muriatic acid) and acalinity, so its hard to just 'try' different possible solutions.

Pool Newbie
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My Pool: 33k gunite, salt, sta-rite system 3, floor system
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Filter won't clear dust

Postby acroy » Fri 30 Apr, 2010 15:53

you might try
-make sure filter has enough sand, and no holes
-make sure all valves are in the right positions and no bypassing (blowing sand into the pool)

Sand is the least effective filter for fine particles...
33k gunite, Clearwater salt, 1.5 & 1hp pumps, floor return jets, fountain, System3 DE, Dirt Devil ProV vac, borates. Soon: efficient pump(s), robot cleaner...
chem geek
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Filter won't clear dust

Postby chem geek » Sat 01 May, 2010 11:40

You can also Add DE to a Sand Filter. Or as was stated above, you can use a flocculant such as OMNI Liquid Floc Plus or you can use a clarifier such as BioGuard Polysheen Blue.

Filter won't clear dust

Postby Paris » Thu 27 May, 2010 04:46

I had the same problem as you.
All experts told me the same story, put more chemicals, more chemicals......
Well, i changed the sand in my sand filter and after just 2 hours i had a crystal clear pool.
Keep an eye on correct chlorine and ph and then do a change in sand.
Remember that you may spend more than 2 hours just to take the sand out. Find out prior doing anything about your sand filter, how many kg of sand needed, how to change the sand, how to put sand, how to check filter laterals and before switching your pump on, do a good backwash then a rinse.

Be well.
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Filter won't clear dust

Postby SPMG » Wed 08 Jun, 2011 10:50

Hello Paris,

If your sand is more than 4 years old it should be changed.
Learn how to do this here

It's better to re-fill with Zeolite which lasts considerably longer.

Alternatively, you can get improved performance and somewhat longer life from your existing filter media by using Jolly Gel. I don't know if this product is available in USA but my advice is to get some and use it!
Read about it here



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