The Three Constants

Every pool professional knows the frustration: you balance a pool perfectly on Monday, only to return the following week to find the same problems cropping up again. Scale on the tile line, aggressive water eating away at surfaces, or that stubborn algae that just won't quit. What if there were unchanging principles you could count on – constants that never vary, regardless of weather, bather load, or customer habits?

In this episode of the Rule Your Pool podcast, Eric Knight from Orenda Technologies breaks down the three fundamental constants that govern every swimming pool, every day. Understanding these principles isn't just academic – it's the difference between fighting water chemistry and working with it.

The Challenge: Information Overload in Pool Chemistry

Before diving into the constants, Knight addresses a common frustration in the industry: information overload. With nearly 200 blog posts, 163+ podcast episodes, and countless resources available, many pool professionals struggle to see how it all fits together.

I see too many pool pros out there struggling with their water, and they're frustrated with problems that keep coming back. For instance, flakes in a saltwater pool, scale on spillways, or tile lines, or in a heater, corroding a heater and you get a turquoise spa, or discolorations on the plaster right around the perimeter, or a lighter color around the main drain.

— Eric Knight, Rule Your Pool Podcast

The key insight here is understanding the difference between water quality (keeping water safe, clean, and clear) and water balance (the physics of how water behaves). Many professionals conflate these two concepts, thinking that clear, chlorinated water must be balanced – but that's not necessarily true.

Constant #1: Water Will Always Seek Its Natural State

The first and perhaps most important constant is that water will always try to return to its natural state of balance. This isn't about what we want the water to do – it's about what physics demands.

Water will always seek its natural state. That's all it wants. It wants balance. Balance is defined by physics, not by you and me, not by mankind, not by a book. Balance is determined by laws of nature.

— Eric Knight, Rule Your Pool Podcast

This balance is measured using the Langelier Saturation Index (LSI). When water isn't balanced:

• If the LSI is low (aggressive water), it will "eat" surfaces to get calcium and reach saturation
• If the LSI is high (scaling water), it will deposit calcium to reduce saturation
• The water doesn't stop until it reaches equilibrium

Understanding this constant helps explain why certain problems persist. That etching around the main drain? That's aggressive water seeking calcium. The scale on your spillway? That's oversaturated water getting rid of excess calcium.

Constant #2: Air Will Equalize with Dissolved Gases (Henry's Law)

The second constant involves Henry's Law, which states that any gas dissolved in a liquid must equalize with that same gas above the liquid. In pool terms, this explains why pH rises and why you can't stop it without understanding the underlying physics.

Think of your pool as a giant carbonated beverage. Just like an open soda goes flat by releasing CO2, your pool loses carbon dioxide to the atmosphere, causing pH to rise. This happens because:

• Pools contain carbonate alkalinity, making them "carbonated"
• CO2 in the water must equalize with CO2 in the air above
• As CO2 is lost, pH rises until it reaches the "pH ceiling"
• This process continues until equilibrium is reached

This constant explains why you can set pH to 7.4, but by the time you reach your next pool, it's already climbing toward 7.6, 7.8, or higher.

Constant #3: Gravity Always Wins

The third constant might seem obvious, but gravity affects pool maintenance in more ways than most professionals realize.

I don't have to agree with gravity, but I have to deal with it. Any of you who do plumbing work or repairs, you're all too familiar with gravity.

— Eric Knight, Rule Your Pool Podcast

Gravity influences:

• Hydraulics: Water always finds its own level
• Chemical distribution: Undiluted muriatic acid (18% denser than water) sinks to the bottom
• Pool filling: Pools always fill from bottom to top, never left to right
• Staining patterns: Vertical lines suggest acid wash damage; horizontal lines indicate startup issues
• Plumbing floods: Pumps below water level without proper valves will flood

Understanding gravity helps diagnose problems and prevent mistakes during maintenance and repairs.

Putting the Constants to Work: A Real-World Example

Knight provides a practical example using typical "ideal" range chemistry numbers:

• pH: 7.4
• Total Alkalinity: 100 ppm
• Calcium Hardness: 300 ppm
• Cyanuric Acid: 40 ppm
• TDS: 3,800 ppm
• Temperature: 82°F

When these numbers are plugged into the Orenda calculator, they yield an LSI of -0.34 – aggressive water that will attack pool surfaces. Even though all individual parameters fall within "acceptable" ranges, the water is out of balance.

You set it to 7.4, and that's great, but a quarterback doesn't throw the ball to where the wide receiver is. A good quarterback throws the ball to where the wide receiver is going. So where's the pH going?

— Eric Knight, Rule Your Pool Podcast

This example illustrates why understanding constants matters more than hitting arbitrary ranges. The pH will rise due to Henry's Law, making the water even more aggressive, while gravity ensures any acid you add improperly will concentrate at the bottom of the pool.

Building Your Business on Constants

The beauty of these three constants is their reliability. Unlike traffic, weather, or customer behavior, these principles never change. You can build your entire service approach around them:

• Plan for pH rise: Set pH slightly lower knowing it will climb
• Focus on LSI balance: Use the calculator to predict water behavior
• Respect gravity: Always dilute chemicals and understand hydraulic principles
• Work with physics: Stop fighting water and start understanding what it wants

This approach transforms pool maintenance from a reactive battle to a proactive partnership with natural forces.

By understanding and working with these three constants – water seeking balance, gas equalization, and gravity – pool professionals can move beyond guesswork and develop predictable, successful maintenance strategies. The water has been trying to tell you what it needs all along; now you have the tools to listen.

Episode Chapters

• 00:00 Introduction and Course Announcement
• 08:30 What Are Constants in Pool Service?
• 12:15 Constant #1: Water Seeks Natural Balance
• 18:45 Constant #2: Henry's Law and Gas Equalization
• 24:20 Constant #3: Gravity Always Wins
• 28:40 Real-World Example Using the Constants
• 35:10 Building Your Business on Reliable Principles