When to Drain a Pool
If the pool vacuum or cleaning service isn't enough to remove all the debris, it may be time for a partial or full drain.
Draining a pool is a massive undertaking. There are countless factors to consider, and disaster may ensue without proper knowledge and expertise.
While some situations may require a pool to be drained, knowing what to avoid is useful.
The dangers of draining a pool
A pool should only be drained when necessary. Rushing to drain a pool may cost not only more than 20,000 gallons worth of water but the entire structure itself.
Here are a few reasons to exercise care when emptying a pool:
Hydrostatic pressure: Without the weight of the pool's water pressing down on the ground, the groundwater from below the pool's shell may surge up and lift the entire structure from the ground. This phenomenon is called a "pool pop" and is particularly prevalent with fiberglass and vinyl pools. This pressure may also crack the floors of a concrete pool. When draining a pool, open the hydrostatic pressure valve to enable some groundwater to enter and the pressure to even out.
Backfill: This is the loose earth shoveled back around the pool's sides once installed. This soil is more loosely packed than the earth surrounding it and collects more water. The water pressure of a full pool keeps this backfill layer in place, but without that weight, the backfill may bend against the sides of the pool, warping and cracking it. One would need to use a sump pump to drain water from the backfill.
UV rays: Pool surfaces, particularly fiberglass, have a protective layer to guard against degradation. This surface is meant to be submerged and, when drained, is exposed to the sun and its UV rays, damaging the surface and compromising the pool's integrity.
Always consult a professional pool cleaning service before attempting to drain a pool. They'll be able to tell you whether or not it's needed and provide safe steps.
When to drain your pool
Here are the main reasons why a pool will need to be drained:
Too much debris: If the pool vacuum or cleaning service isn't enough to remove all the debris, it may be time for a partial or full drain. Turn the pool pump to "waste" mode and start flushing. One can treat most debris problems and severe algae with less drastic methods. Ask your pool cleaner about shock treatment for stubborn algae.
Significant repairs: The pool may have sprung a leak, or the underwater light needs a new seal. Draining the pool allows the affected area to dry and for any sealant or replaster to set.
High TDS: Total dissolved solids are waste particles (oil, hair, skin, etc.) that accumulate over time in a pool. When the total ratio exceeds 2500 ppm, pool chemicals become ineffective, and the water can't be effectively balanced. Rather than waste money on chemicals, the pool needs to be drained and refilled. However, one should do this every five to seven years.
Calcium hardness: Calcium buildup, or any chemical imbalance, must be remedied with a partial pool drain. If the calcium levels exceed 400 ppm, calcium scales will start forming and corrode any metal parts of the swimming pool. Fresh water is needed to balance these levels out.
Check the rules and regulations
Be sure to check with municipal bylaws, as you can incur fines for draining a pool. However, a professional pool cleaner should know these laws and help you navigate them to drain your pool without fines.
