Greetings from sunny Singapore!
I chanced upon TFP while scouring the web for the possible causes and solutions to my hazy pool issue, and I must say, it's been very informative and useful in terms on pool maintenance and issues. Having tried a few options out (after quite some research), I've decided to post my questions to this forum to hopefully find something more definitive, in terms of possible causes and solutions.
We get year round sunshine in Singapore, so our swim season all year long. So it's almost of "full time" job to keep the pool clean and running well. We've had the pool for >20 years now, and had recently (> 3 years ago) changed the DE filter system to a sand filter system, and re-tiled the pool. Since then, the pool has been running nicely, but we've never been able to get the water to "sparkling" quality (like we did when we had the DE filtration system). For a few months now, we've been trying ways and means to get that clear water quality - ie rebalancing the water chemistry, adding Alum (with Soda Ash) to the sand filters (supposed to improve filtration of minute particles), brushing, increasing filter pump activity (24+ hrs), vacuuming every other day - stopping short of completely replacing the water in the pool.
The water is of a hazy quality, we can see the bottom in the day, but it's not truly clear. The turbidity is more apparent at night when the pool lights come on. Below are the readouts from the pool chemistry test I just did today:
FC - 2ppm
TC - 2ppm
pH - 7.4
TA - 80ppm
Water Hardness (at least this is what it's called in the test kit) - 200ppm
CYA - 60ppm
We just added about 3lbs of Sodium Bicarbonate last weekend to raise the TA (which was at 70ppm). Based on the PoolMath calculator, I need to add an additional 4lbs of Sodium Bicarb to get my TA to 100ppm. Will doing this improve with the haziness of the water quality? I had avoided adding the full 7lbs simply because there appears to be a little bit of a light white coating on the tiles on the top of the pool edge when they are dry in between pump activity. I'm not sure if adding more Sodium Bicarb would exacerbate this.
Is it possible to determine what the cause of the water haziness? I've been told (by the local pool "experts") that it might be Calcium Chloride precipitation due to the Chlorine we use (had previously used Cl granules (trichlor) to maintain the FC levels, and now it's mostly Cl tablets); another reason is that the sand filter is not filtering everything, so we added Alum (aluminum sulphate) to hopefully increase the efficiency. I just read about adding DE to sand filters, is this more effective than Alum? I've also held off adding a pool clarifier, as I'm not a fan of adding unnecessary chemicals to the water. Other reasons for haziness include dead algae, or too much sodium bicarb, too much CYA etc.
Would greatly appreciate any advice you might have in terms of the possible causes of the haziness of the water quality, and what I can do to solve it? Am at a loss, as I'm getting pretty confused :P
Thank you in advance and I look forward to hearing from you