Pool Milk

[At last straw]

Problem: Help me please. My pool looks like watered down milk. I've tried clarifiers, shocking, stabilizers and algicides, still milky. If I turn the pump off for about 12 hours the water is clear with a white film on the bottom of the pool. The film does not quite settle entirely to the botttom, stays suspended about 1/2" along bottom. Tried vacuuming but every time a move the water the cloud rises back and seem to be to fine to vacuum. With out any other ideas I will have to drain the pool and start over.

FC:4
TC:
pH: 7.3
TA: 130
CH:
CYA:

My pool:Intex Steel Frame pool 1700 gal/6500L
Pool chemicals: Chlorine granulars
My pump & filter: Cartridge filter
Other info:I clean my filter daily and there is always a white slime covering the filter.

Any help would be greatly appreciated.

[swimnsaveusa]

You need to test your water for TDS (total dissolved solids). This may be your problem!

[at last straw]

Thank you Swimnsaveusa.

How is the best way to test for TDS (Total Dissolved Solids)?

I'm assuming that my TDS is high, how is the best (most effective) way of reducing it?

[chem geek]

It's not TDS that is the problem, which would be mostly salt anyway. Intex pools are notorious for having lousy pumps and inadequate filters. Did you use some sort of phosphate remover or anything like that prior to getting this cloudiness? Since your pool only has 1700 gallons, you could consider draining and starting over with fresh water which might be easier than trying to remove what is in the water through filtration.

[swimnsaveusa]

Chemgeek, this is not true. TDS is NOT only limited to salt. TDS is can be a result of agricultural and residential runoff, leaching of soil contamination and point source water. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride, which are found in nutrient runoff (from the roof into the pool after rain or carried by wind), sprinklers, rain water, dirty bathers (why commercial pools require showering first). The best way to test for TDS, is to take a sample into the local pool store and ask for it. This should be free, will take seconds, and it will not hurt to check as this can be a cause of many problems most people don't think to check. Also, if your alkalinity is high when they check TDS, be sure they are using the corrected formula as this will give you a false "ok" reading.

[chem geek]

If you are worried about calcium carbonate clouding, then testing for Total Alkainity, pH and Calcium Hardness (CH) and Cyanuric Acid (CYA) will let you calculate the saturation index. All the minerals you cite such as magnesium, potassium, chloride and nitrates do not cloud water. Very high phosphates with high calcium can cloud. High phosphate and nitrate levels can have algae grow faster and that will initially look like dull and then cloudy water before turning green, BUT a sufficient Free Chlorine (FC) level relative to the Cyanuric Acid (CYA) level will kill algae faster than it can grow regardless of nutrient (phosphate, nitrate) level. My pool has had more than 3000 ppb phosphates yet is kept algae-free by chlorinating liquid alone (it's shown here and here).

TDS is mostly salt -- the calcium and bicarbonate from initial startup plus the sodium and chloride from chlorine usage since chlorine turns into chloride when it is used up and sodium comes from either bleach or chlorinating liquid or if using stabilized chlorine, pH and TA adjustment products (if using Cal-Hypo, the CH will rise). If one is using stabilized chlorine, then the CYA can build up and that lowers the active chlorine level unless the FC is raised proportionately so in that sense a higher TDS is a proxy for the high CYA, but it's the high CYA that is the problem, not the TDS itself. The pool industry has historically blamed TDS because they didn't want to point to the real culprit in most circumstances which is the buildup of CYA from stabilized chlorine and its reducing chlorine effectiveness against killing algae.

The conductivity tests used to measure TDS don't even measure the uncharged molecules in the water such as urea or chlorourea. Yes, there can be organics in the water, but they don't always show up as TDS when measured via conductivity. Even so, the amount of ogranics will be swamped by the amount of calcium, bicarbonate, and sodium chloride salt so won't be obvious anyway.

I write more about how TDS is sometimes used as a proxy for the age of the water in this thread on improving the CPO course/manual.

[at last straw]

Thank You chem geek and swimnsaveusa for your time and help. I believe that I could spent alot of money on testing, chemicals and filteration in order to resolve this problem. With such a small pool I will drain and clean it out and refill it.

Thanks again for your time and help.

p.s. chem geek you have a very nice pool.