The Commercial Pool Whitecoat Experiment

The Experiment
by Rob Cox October 15, 2014

The Big Pool Plaster Experiment

I was contacted recently about a blog post written way back in 2010, titled When is it Time to Replaster the Pool? In this post, I describe how I had just returned from a pool board meeting (which I was serving on for a local community pool). There was a line item on the budget, planning for a replaster of the pool every 10 years.

The person emailing me about the blog post was also a local community pool board member, who let me know that on their budget, they have a line item for replacing the pool plaster every 5 years - at a cost of $120,000!

I was blown away by this - why would a pool, even a heavily used commercial pool, need to replaster the pool every five years? Pool plaster is meant to degrade eventually, but in a residential pool, you can easily go 15, even 20 years between whitecoats.

The Problem:

I have a theory, a conspiracy theory really. Pool management companies, who rely on extra work from their accounts to remain profitable, are accelerating the plaster degradation with aggressive annual acid washing of the pool.

It's partially the fault of the business model. In our area, pool management companies compete on price for seasonal management contracts for community pools, providing a turnkey price for opening and closing, chemicals, lifeguards and pool managers.

Then they hope for as much rain as possible, to reduce labor costs. They cut corners on water balancing chemicals and proper shocking of the pool. And, they submit proposals all summer long for repairs that may or may not be needed. For example, the filter replacement proposal of $1600 I once saw, because the filter was leaking. I replaced a 30 cent o-ring on the air bleeder, and we were all set, thank you very much.

Pool management companies want skimmer replacements, pump motor rebuilds, new caulking, new cover, new plaster. And how about some new tile and coping while were at it? This is how they make their money. Can't blame them for trying.

The Question:

Back to the pool plaster question - why would a pool need to replaster every five years? Maybe they have a real stickler health inspector who told him to plan on replastering so often. Or perhaps certain pool management companies, when they open the pool each spring, do as much damage to the pool plaster as possible, pouring straight acid on the pool walls, not rinsing quickly or properly, and not neutralizing the waste water. After 4 or 5 years of this treatment, the plaster is rough and pitted, and the kids are all crying about 'pool toe'.

The Experiment:

"Spend $1000 each year on chemicals and cleaning, and save $10000 per year on plaster costs"

My solution is to simply winterize commercial pools the same way that we do residential pools. Clean them, Chemical them and Cover them. In the spring, the pool is a little messy, but we don't drain and acid wash - we start the filter, clean the pool, balance the water and shock the pool.

The experiment is being done on my old community pool (DT). They not only want to preserve the plaster as long as possible, but want to avoid the $5000 it costs to refill the pool every spring. Added bonus of not pumping acid waste water into the Four Mile Run creek each year.

Below is a new method of closing a large commercial pool. DT pool is 170,000 gallons (when full), and is covered by a very old, threadbare mesh safety cover. Add enough chemicals, and do some cleaning during winter (and a lot of cleaning in spring), and they don't have to drain and acid wash the pool each year.


Homemade pool chlorine floater, Freezer Ziploc, Pool Noodle, Chlorine tablets

  • Balance the pool water: pH: 7.4, Alkalinity: 100, Hardness: 200, CYA: 20-50, Chlorine: 2-4
  • Clean the pool by skimming, vacuuming and brushing
  • Lower the pool water to winter level – 15-18” below tile line
  • Shock the pool with liquid or granular chlorine
    • Liquid – pour 1 gallon per 5000 gallons pool water
    • Granular – broadcast 1lb per 5000 gallons pool water
  • Winterize pipes by blowing and plugging, or using pool antifreeze
  •  Add chlorine tablet floaters, using 5 tablets per 10000 gals pool water
  • Cover the pool – making sure all straps are attached.
  •  Add 1 qt of Poly 60 algaecide per 25000 gallons. (1gal/100K)Poly 60 winter algaecide - 1/2 gallon
  • Open cover along one long side of pool to pour in algaecide
    • Add twice during winter:
      • 1-2 weeks after closing +/- October 01
      • 4-8 weeks before opening +/- late March
  • Maintain water level in pool to prevent water warming and leeching leaves
    • You can use an automatic pump, placed on second step, or use a siphon
    • If you see a ‘wet spot’ in cover center, water is too high
    • Especially important during the months before opening
  • Remove any leaves / debris that accumulate on or around the pool cover

  • In early spring, (March) check and refill chlorine floaters
  • In mid spring, (April) add another dose of pool algaecideclean and vacuum the pool
  • Lower pool water level if needed to prevent the ‘wet spot’
  • Remove any pockets of leaves (if noticed) in the pool
  • Clean the pool cover (if needed) of leaves or debris 


  • Remove pool cover, add water, de-winterize and begin filtration
  • Test and balance water chemistry, filter overnight, retest the next day
  • Shock the pool – 1 gal or 1 lb per 5000 gallons pool water
  • Vacuum. Brush and Skim pool clean, 1-2 man hrs/1000 sq ft of area
  • If pool has trouble with algae, recommend test for phosphates; treatment
  • If pool opens with lots of leaves or algae, clean pool before shocking, then clean again
  • If pool is in very urban area or in flight path of landing air traffic, recommend using enzymes
  • Some staining of plaster may be unavoidable
    • Localized stains can be removed with a Stain Master tool
    • Shocking with granular chlorine will remove most organic stains
    • Plaster stains lighten after a week of chlorine and sunshine
This method can be used to avoid draining and cleaning the pool, or it could be used with draining/hosing the pool (no acid), or draining and only lightly spot acid washing certain areas.
Light acid washing (1:4 - acid:water mix) will remove most stains without plaster degradation, when rinsed quickly and thoroughly.  
Acid washing is not needed every year, and when done, should be performed cautiously – to protect the plaster. You may wish to plan on acid washing every 3-5 years, to restore some luster, and change the water – but with explicit instructions and supervision of the people who are doing the job.
Pool plaster can last 10 years or more in a commercial pool environment, when it’s taken care of – during winter and during spring start-up, and during acid washing.

I will report on the results of the experiment next spring!


- Rob