+0.31 and above (purple) = oversaturation of CaCO3. This is where Calcium carbonate precipitates out of solution when your LSI is too high, also know as "Scaling" which will result in, Scale formation in your Pool, Pool Equipmet/Heater/Salt cell, carbonate clouding, calcium dust etc... 

 

0.00 to +0.30 (green) = ideal balance of CaCO3. This is where the water is HAPPY!

 

-0.30 to -0.01 (yellow) = acceptable balance of CaCO3. This is where the water is close enough to happy, though slightly undersaturated.

 

-0.31 and below (red) = undersaturation of CaCO3. Where the water is starving for calcium carbonate. Water will seek and dissolve it wherever it can be found, and if it cannot be found, it will keep eating through everything it touches until it does find it. Otherwise know as Etching.  DANGER ZONE!

 

What the LSI teaches us

Water itself only wants one thing: equilibrium. That equilibrium is measured on the LSI. Either you balance the water according to the LSI, or the water will seek to balance itself.  If it has too much CaCO3 in its current conditions, water will release some to get back down to equilibrium (scale, dust, cloudiness, etc.). If it has too little CaCO3 in its current conditions, water will find it and steal it by dissolving CaCO3 into solution from cement or tile grout. If no calcium carbonate is readily available, the water will destroy just about anything looking for it (fading vinyl liners, degrading gelcoats on fiberglass pools, etc.).

Maintain LSI balance year-round and why its important

Our first pillar of proactive pool care is about maintaining LSI balance all year long. most people have thier pools professionally maintained throughout the summer but what happens when they close the pool and within two months theres a tempiture drop of over 40 degrees? the cold truth is that your waters LSI drops so far into the negative that it starts eating away at your pools surface, lets see what happens when this occors:

Liner pools- everything under the water level will start to fade in color and eventually you will no longer be able to see the print of the pool liner, it will all be one single color or very patchy. most people (companies) typically say two things; they say this is from the sun and over time will happen no matter what but that is simply not true, liners are specifically made with built in uv protection and if that was the case wouldnt the liner above the water line be effected too? they also say its from chlorine bleaching, but normal liners have built in chlorine resistance, meaning you can keep them at a realitively high level all summer long without any issues (when maintaining a good LSI). be warned you can still bleach your liner by letting straight chlorine sit on the liner no mater the LSI, so be very carful when shocking that no shocks falls to the floor and please, please, please never throw a chlorine tablet straight into the pool this will most certantly bleach it.

 

Many variations of Concrete pools- will start to realease calcium and in most cases will reasult in large color fading patches known as etching that cannot be fixed without a complete resurfacing of the pool. in some cases the LSI has been so bad throughout the winter that at the spring openning there is "white dust" all over the pool this is called snow flaking. This happens when the water was so hungry for calcium that it ended up pulling too much from the walls and it fell out of sulution.

 

Fiberglass pools

FG pools have a protective gel coat finish that makes them smooth and beautiful, but when the LSI is not taken care of the water always gets supper aggressive throughout the winter (this is when we see the most damage done) the water is always seeking a happy LSI balanace, the main thing it does to get into balance is search for calcium... but theres no calcium in the fiberglass gelcoat right? but it doesnt care, its starving and will start eating through anything in its way to have equilibrium. this causes unreaversable damage. the gel coat gets micro cracks all over it in weird paterns (depending on how it was originally aplied during its manufacturing proccess) then chlorine gets into those micro cracks and begins to oxidize the gel coat. lets see what happens to the common fiberglass colors below.

 

White fiberglass- seems to have the worst side effects of having a negative LSI. when the gel coat gets eaten into a few winters in a row, its starts to release a milk like pigment known as "milking" every time someone or something brushs up against the walls and or floor, which is very unsightly especially when it causes the entire pool to get very cloudy within only a few minutes. it takes hour to settle which leaves behind a thin layer of seddement as well as cloggs up your filters causing excessive wear and tear shaving years off its expected lifespan.

 

Dark blue fiberglass- does not get effected like the white fiberglass does, which is good but some people think it gets effected visually worse... when this color pool gets its gel coat attached and then oxidized it turns from what used to be a smooth beautiful blue pool that literally shines/sparkles into a hazy dull white color that gets worse and worse each year the LSI is neglected. weve seen this happen as soon as after the first winter. Please see photos below of what you can expect within only a couple years.

 

Light blue fiberglass- hides a neglected LSI very well, although the same problems are occuring to this color as the dark blue, you arent able to tell as much due to its color. dont get us wrong, these pools are still getting destroyed but you may not be able to tell until its a few years in. 

Now lets look at the contributing factors that make LSI so much fun

 

1-Water temp. Lets face it, your pools water temp is constantly changing, thats why you probably have a heater right? when your water temp changes so does your LSI value. The chemicals your pool needs to have your water at a perfect 0.00 LSI at 80 degrees is completly differrent then when your water temp is 70 degrees, 60 degrees, 50 degrees, 40 degrees, yes you guessed it, it needs different chemical levels even when your water reaches 32 degrees (freezing point) where it will hit in NJ. THE COLDER YOUR WATER GETS THE MORE AGREESIVE IT BECOMES, because it plumits the LSI futher and futher into the negative the colder it gets.

 

2-PH. pH stands for "potenz Hydrogen", or in English, the "power of Hydrogen". It is a value between 0 and 14, which determines how acidic or basic a substance is.  7.0 (in the middle) is perfectly neutral. Every whole number is 10x greater or less than the next whole number. (Example: 6.0 pH is 10x more acidic than 7.0.  5.0 pH is 100x more acidic than 7.0, because it's 10x10, so on and so forth. thanks to Alkalinity, PH is constantly on the rise... until it his it PH ceiling (henrys law)

 

3-Carbonate/corrected Alkalinity. Corrected Alkalinity (CA) = Total Alkalinity (TA) - (CYA x [correction factor @ pH]). Carbonate Alkalinity will determin where the PH ceiling is. Alkalinity and PH have a very close relationship, in most cases you cannot touch one without moving the other.

 

4-Calcium hardness. Is one of the most important factors in water chemistry, and swimming pool chemistry especially. It is one of the six LSI factors, and because it does not fluctuate much, we love using calcium hardness as a foundation for water balance, The amount of CaCO3 (ppm or mg/L) is calcium hardness, but how saturated the water is with that calcium hardness is the LSI.

 

5-Cyanuric Acid. (CYA) Also called conditioner or stabilizer. CYA is a chemical used to protect chlorine from direct sunlight. Direct sunlight can break down chlorine in a matter of hours. So without protection, chlorine does not last very long in outdoor pools. On the flip side the more CYA in the water the less effective the chlorine is. You'll need a higher and higher level of free available chlorine as your CYA levels go up t do the same job as when both CYA and chlorine levels were lower.

 

6-Total Dissolved Solids. (TDS) is a metric used in water treatment that measures all dissolved minerals, salts, chlorides, metals, organics, and many other contaminants in water. TDS impacts water conductivity and is related to corrosion, chemical efficiency, water clarity, and is an often-forgotten factor in the LSI.

 

PLEASE NOTE, WHEN ONE OF THESE FACTORS CHANCE, THE ENTIRE LSI CHANGES.

The Langelier Saturation Index (LSI) is the objective/unbiased measurement of water balance. It tells us the saturation equilibrium of calcium carbonate (CaCO3). Water always seeks equilibrium, and we measure that equilibrium using the LSI. The LSI is the aggregate of six factors: Water temp, PH, Carbonate Alkalinity, Cyanuric Acid, Calcium Hardness, and Total Dissolved Solids (7 if counting borates). It determines if our water is aggressive/corrosive (low LSI), balanced, or scale-forming (high LSI). It sounds simple enough, but let's dive in and show you just how much it matters to other aspects of water chemistry.

LSI Balance

When calculated, the LSI is a number value on a spectrum where 0.00 is perfectly balanced.

After a gel coat is destroyed you only have two options, live with it or get it resurfaced. Unfortunatily the risk facter of a fiberglass pool popping out of the gound due to the high ground water we've never seen a company willing to resurface these pools on LBI.

*MOST OF EVERYTHING ON THIS PAGE HAS BEEN SIGHTED FROM ORENDA TECHNOLIGIES*