What does prime loss mean?
Let's begin by understanding what "prime" means.
A pump that is pumping water is considered "primed". A pump that is off, full, and ready to work is also considered primed or "holding it's prime". Swimming pool pumps should maintain a "fully primed" state, even while they are off.
Even though practically all pool pumps are considered "self priming pumps", swimming pool systems are supposed to stay 100% full of water, 24 hours a day.
Yes, even while the system is turned off...indefinitely!
The water in your pool equipment cannot drain out unless something else can replace it.
Remember holding soda up in a straw with your finger over the tip? That's the exact same principle! The soda cannot drain out of the straw until you remove your finger, allowing gravity to draw the soda down and out of the straw. Then as the soda drains, AIR replaces it.
When air has been allowed to enter the system, and a pool pump has lost it's prime, in theory it should re-prime itself. However a pump that has to re-prime itself every day can experience heat damage to the rubber portions of the mechanical shaft seal, causing it to leak prematurly. That's not good.
Did you notice in the previous paragraph it says that in theory a pump should re-prime itself? This is because many times, the source of the air that was allowed to enter the system is on the intake side of the pump, and this can keep a pump from priming as it should. That is where the real problems can begin.
When a pump is running without a prime long enough (this could be as little as 20 minutes), the friction created by the mechanical shaft seal (which is water cooled), can create enough heat to reach a temperature high enough to begin to soften PVC pipe and fittings. Once a threaded PVC fitting has been exposed to that amount of heat, it will most likely begin to leak at the threads. We have also seen some brands of pumps sustain;
Seal damage
Seal plate damage
Strainer basket damage
Trap cover (pump lid) damage
All of these can happen by simply ignoring that little drip. Don't take chances and let the seemingly little things go. Take care of even the most minor problems, to avoid more costly repairs.
REMEMBER!
Hire only State Certified Swimming Pool Contractors for repairs...IT'S THE LAW!!