Do more solids in the water affect clarity?

[upnorthpoolguy]

This post was split from Negatives of using bleach and bleach vs liquid chlorine . Please start a new thread if the one you are interested in posting to has been dormant for more than a year. Zea3

Ignore TDS. There is no point in even thinking about TDS. TDS has absolutely no bearing on anything to do with pools.

Raising the FC level by a fixed amount adds more or less the same amount of salt regardless of what strength of bleach you use.

What? Total dissolved solids in pool water has no bearing on your water? This is not what I have been told. It would seem that more solids in the water would affect clarity, no?

 

[chem geek]

Welcome to TFP!

Saltwater is clear and has "solids" in it but they are "dissolved". That is what TDS is -- Total Dissolved Solids. When solids dissolve in water they do not affect water clarity unless the ions (or molecules) absorb light to color the water (such as copper making the water look green or iron making the water look yellow). Water itself absorbs some red light so in depth it looks blue.

Saltwater chlorine generator (SWCG) pools usually run with 3000 ppm salt (TDS slightly higher) and are no less clear than a pool with < 500 ppm salt.

There is a LOT that the pool industry simply gets wrong. You've come to the right place if you want to learn the truth. Just look at the pools on the home page of TFP in the slideshow and notice their clarity. Many of them are SWCG pools.

When dissolved chemicals get to the saturation point, that is when they can begin to precipitate and cloud a pool. This can happen if one over-saturates the water with calcium carbonate and is most noticeable when adding pH Up (sodium carbonate) product to a pool.

Note that while there may be 100 Reasons for Cloudy Pool Water, the #1 reason by far is too low an FC for the CYA level which allows algae to grow faster than chlorine can kill it thereby making the water dull/cloudy if not a full-fledged green algae bloom.

 

[ranger_ric]

I have extremely high TDS and yet my water clarity is AWESOME!! No way for me to remove CH and I have a vinyl pool so I celebrate having crystal clear water and no Germs in my Ool!!!

 

[upnorthpoolguy]

So to be clear (slight pun intended ) when the "other guys" say using liquid chlorine will raise tds, it isn't a problem?

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Also, what are these dissolved solids in bleach?

 

[Richard320]

So to be clear (slight pun intended ) when the "other guys" say using liquid chlorine will raise tds, it isn't a problem?

That is correct. The TDS you're adding is just salt.

Dissolved solids means just that -- dissolved. How much sugar is dissolved in Sprite? Does it look cloudy? Undissolved solids - like dust and dead skin and algae carcasses - will cloud a pool. That's what the filter is for.

Edit:

A 12 ounce (354 ml) can of Sprite has 39 grams of Sugar. 354 ml of water weighs 354 grams. So...

39/354 * 1,000,000 = 110,169 ppm. You'd think it would look like milk if TDS affected clarity.

 

[JVTrain]

The TDS in bleach is largely salt. 1 gallon of 8.25% bleach will add 8.5 ppm of free chlorine and 14 ppm of salt in a 10K gallon pool. (via Pool Math)

TDS level for a pool is equivalent to telling you there's flavor in your food. What kind of flavor determines whether it's good or not.

CYA, salt, CH, etc are all components that contribute to the TDS number. TDS number by itself is rather meaningless.

 

[upnorthpoolguy]

Thanks everyone. That's good stuff!! Often we hear something at the pool store and think it sounds logical and therefore must be true. It is great to hear from people who truly know. But because of Richard320, I now want a Sprite!!

 

[jblizzle]

What "the other guys" fail to tell you is that trichlor, dichlor and cal-hypo all ALSO add salt to the pool. The first 2 also add CYA and the cal-hypo adds calcium ... both of which are included in the TDS measurement as well

 

[jblizzle]

Some results from PoolMath when you add 10ppm of FC to your pool you also add:
bleach: 16ppm of salt
trichlor: 8.4ppm of salt and 6.2ppm of CYA
dichlor: 8.1ppm of salt and 9.1ppm of CYA
cal-hypo 65%: 10ppm of salt and 7.2ppm of CH

So the solid forms of chlorine add at least half as much salt as bleach, but also have the side-effects of CYA or CH which are bad if they get too high. The salt from bleach will never get too high, so there are no problems.