Pool Finish

This page covers various details regarding the pool finish. Originally, this page referred to "marcite", the finish present before September 2022. Marcite is a mixture of Portland cement, marble dust, and fortifying additives. Silica and quartz aggregate may be mixed in to improve appearance and durability.

Maintenance

Basic principles should be followed to aid in the longevity of the pool finish:

• Keep chemicals in balance at all times. Unbalanced pool chemistry may result in "spot etching" of the finish.
• Avoid acid washing wherever possible. Covering the pool off-season greatly reduces the need to acid wash.

Patching

Patching of holes may periodically be needed, especially as the finish ages. Assume $300-500 per hole patched, though this number is very much subject to change. The contractor requires the water temperature to be above 75 degrees (presumably for the sake of the divers). This, of course, is most relevant for work in the early season before the boiler is operating. After a patch, allow at least 24 hours to cure before opening the area to swimmers.

Replacement

In the past, marcite was usually only repaired. Problem spots were removed, and a new bond coat and plaster (marcite) were placed over old. As a result, refinished pools may contain many layers. For the next replacement (2022), these layers will mostly need to be removed. This aligns with the recommendations of the National Plasterers Council.

Plan for 2022

Replacement of the pool finished is planned for September 6th, 2022. Work is planned to commence as quickly as possible following the pool closure to members (Tuesday after Labor Day). The pool will need to be chemically treated for about 30 days following job completion to allow the finish to fully and properly cure.

Quotes were originally in late season 2020 for budgetary purposes. Updated quotes were obtained for 2022. Due to the potentially sensitive nature of the pricing, the details are not included here. B&G has full records on file.

Some additional items will be associated with this project:

• The replacement of the filter sand and tank internals (see this link). For budget reasons, this is planned to be deferred to 2023, before the opening of the pool.
• The replacement of light fixture niche(s) and at least one fixture (as lights will have to be pulled during the work anyhow). Conversion to LED is being considered.
• Piping work that can only be completed when the pool is drained:
  • Replacement of 8" isolation valves on main drain line in the pump house.
  • Installation of a motorized valve on the main drain line (for surge tank modulation).

Requirements

Contractors quoting marcite replacement should include:

• A marcite or quartz aggregate finish (preferred for improved durability over marcite). A pebble finish is not currently being considered.
  • Finish to 3/8" to 1/2" thickness (some variation due to imperfect gunite finish expected).
• Chip and/or waster blast strip preparation. The former is more common. Some companies will do a full strip (down to gunite), while others recommend stripping at least two layers (the more the better, in general).
• Tile replacement (cobalt blue or equivalent). Features include:
  • 180 ft for step edge markers
  • 6 x 75 ft of lanes and targets
  • A break marker (depth indicator)
• Caulking

Depending on the quote, some of the line items above might be included in base pricing.

Additional requirements:

• A warranty period of at least one year. Two years appear to be standard for a quartz aggregate finish.
• Local references.
• Verified insurance, per standard practice, when hiring contractors.

Ideally, the contractor should NOT utilize a sub-contractor. This will add cost. The job is estimated to take 2-3 weeks to complete.

Preparation

Static pressure due to groundwater is a concern. Hydrostats from the main drain will need to be removed, and the contractor may also need to drill additional pressure relief holes. Well point dewatering is not planned.

The current best practice is to strip as many layers as possible. The stairs should be stripped, too. This may result in some corners of the gunite breaking off. The stairs may need to be rebuilt as a result. This may be desirable, as the stairs are presently slightly sloped downwards

Engineering Support

It has been suggested that an engineering firm is not required for this project. The biggest concern for any contractor is dealing with hydrostatic pressure.

Curing Process

• Fill the pool to the proper level as quickly as possible to minimize shrinkage. This must be completed within 24 hours (within the day if the weather is hot).
• A metal sequestering agent may need to be added to the pool - verify with the contractor.
• Chemicals must be balanced as quickly as possible to protect the new finish.
  • Adjust alkalinity and pH (pH may be kept slightly on the acidic side, though within the 7.2 to 7.6 range)
  • The chlorine level should be brought up slowly.
  • Water balance will be more difficult than usual due to the very high calcium level in the marcite product.
• Use a nylon brush on the walls and floor at least once per day for the first two weeks, then 3-4 times per week in the last two weeks.
• Regular backwashing will be necessary, as pressure will build more quickly due to the marcite dust in the water.