Cloudy water and oily film

Causes and cures for cloudy swimming pool water.
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Cloudy water and oily film

Postby Guest » Wed 14 May, 2008 13:29

We have an 11000 gallon above ground pool with sand filter. We bought our house last October and just opened the pool last weekend. It was a gross green, murky mess. Our initial numbers from the pool store on Saturday were

FAC: 0
pH: 7.8
TA: 20
CH: 50
CYA: 0

After adding condition, alkalinity up, shock and algae control the pool is a very milky light green/blue color. We had the water re-tested at the pool store (and bought a kit, which we used to confirm their numbers). The numbers yesterday were:

FAC: 5
TAC: 5
pH: 7.4 (with my kit I get 7.2)
TA: 180 (my kit shows closer to 200)
CH: 70
CYA: 30
TDS: 150
Copper/Iron: 0

We added a dose of clarifier last night and when we found no change this morning (after leaving filter off last night) we added another dose. The second dose brought a layer of nasty foamy brown scum to the top of the water which the pump has taken care of.

However, the water is still very cloudy with white, silty particles and there is an oily film on top of the water.

I'm not sure what else to try. I've read that high TA can cause the pool to cloud, but my pH is so low I don't want to get caught on the TA/pH yo-yo I've read about (lowering TA lowers pH, increasing pH increases TA, back and forth).

I also retested the FC level this morning and it held steady overnight at 5, so I think we got all the algae.

If it matters, the pool was previously on Baquacil but the test strips the previous owners left don't show any left in the pool and the sand is new so it doesn't have any either.

Also, how do we know the filter is working properly? We changed the sand when we opened the pool because we didn't have any suction and after tightening everything up really well we finally got it pumping. We're just wondering because the water is coming out of the return jet very fast. If the water is coming out so fast is it being filtered enough?

This is our first pool so we're totally clueless! Any ideas or advice?



Cloudy water and oily film

Postby Guest » Mon 07 Dec, 2009 02:47

hi. i run a commercial pool. you need to add 20 kg of bicarb soda....this will clear your water and yes, even though your pimps are running fast they are running corrctly. if you need to contact me you can at [email protected]. any time. cheers.
chem geek
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Cloudy water and oily film

Postby chem geek » Mon 07 Dec, 2009 04:45

The original poster (and this is an old post 5/14/08) had a TA of 180-200 after they added Alkalinity Up. Adding more bicarb is not the answer and is not something that would clear a pool anyway. Since they indicated the pool had been using Baquacil before, then it's possible there is some leftover (though not enough to show in the test strips) so more chlorine to oxidize the remaining Baquacil and/or algae is what is needed. The fact that the chlorine didn't drop overnight doesn't mean that a higher level won't oxidize what is left, albeit slowly over a few days. So shocking with 12-15 ppm FC given the 30 ppm CYA would be the prescription here.

Some Baquacil conversion pics are shown here and here where you can see the color changes and floating particles. It's possible that this poster's pool has only a little Baquacil left, but is the source of the color, film and particles. Shocking with chlorine (or another oxidizer such as sodium percarbonate) will clear the pool. Having the CYA in the pool may make the conversion using chlorine take longer as it reduces the active chlorine concentration.

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