Getting your pool ready for summer
There is lots of information available for keeping your pool water in tiptop condition, but if you are emptying your pool, it is an ideal time to carry out essential maintenance to the structure, tiling and pipework etc. This year, the two main manufacturers of repair materials have finally come up with semi flexible tanking mortars, and one manufacturer has changed the product names for their entire catalogue. The new products and names are therefore all detailed in this article.
There are a number of different types of pool, for the purpose of repairs we will focus on the most common type of built pools (‘de obra’) i.e. of block and normally steel reinforced concrete construction. (many water deposits which are often later used as pools are built in the same way).
Most built pools are either lined with ceramic tiles, or painted with a special pool paint. While some tile replacement can be carried out underwater using special materials (see below), most repairs are best carried out with the pool empty.
Pools should never be emptied or filled too quickly as the structure will move due to the significant changes in pressure, (an average sized pool contains around 70 metric tonnes of water). Allow 48 hrs + for both filling and emptying, and avoid leaving the pool without water for long periods.
Once empty, first carry out some checks to decide on maintenance needed.
You will probably be surprised by the depth of your pool when empty as it appears more shallow when full of water.
Empty pools are just as dangerous as full ones. Protect them from children and try not to fall in, (I did once and found that a 2m fall onto concrete hurts a lot more than 20 cm into water).
Main Checks
- Remove loose tiles to allow substrate to dry.
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Tap all fixed tiles with a coin to establish if they are still well keyed. You will quickly note the difference in tap tone, between a well fixed tile, and one that has lost most of the key, such that it is likely to come loose soon. Also remove these poorly keyed tiles.
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Check tile grout to see that it is in good condition. Overtime the grout between tiles will erode and need renewing.
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Check your bottom outlet (‘sumidero’) to see that it is well sealed to the pool base. Older types (metal or cement) are best replaced with plastic, especially if they connect to old iron pipework. As pipework is normally set in the strong reinforced concrete structure, it is usually more practical to run a new PVC pipe (of smaller bore) within the older iron pipe, effectively using the iron pipe that goes through the pool wall as a duct. Many pool leaks are due to failed pipework and outlet seals, rather than the structure itself, so make sure the condition of all pipes and seals are checked properly before you assume the pool itself is leaking.
Also remove jet heads and check that the junction with the pool wall is well sealed. Skimmers can also leak and may need re-sealing. Fortunately the water pressure at jet and skimmer level is so low that slight leaks might be tolerated. It is the ‘sumidero’ bottom outlet and lower pipework that will result in fast water loss if leaking.
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If you suspect your pool is leaking, all tiles may need to be removed to establish the location of the leak (painted pools will probably make crack identification easy), while a spot repair may be possible (see below), it may be necessary to re-make the pool structure e.g. with reinforced ‘Gunite’ (‘Gunita’ in Spanish) or a tanking render or slurry coat (see below). The guniting is best carried out by a specialist company and will be costly, because effectively it involves remaking a pool within a pool. If your pool is above ground you may be able to see the location of a leak (often evident with green algae or lichen growth on the outer wall), but water sources can be very difficult to locate and water may have tracked from a failed area of the concrete structure to a different area of the block surround before emerging, so make sure you inspect the pool thoroughly. If you don’t want to remove tiles, you might consider adding a liner. (A specialist company can normally line a built pool with a plastic liner as used for example in timber or steel framed pools, (liners are available in tiled effects too). It may be necessary to level the pool base with sand to incorporate some liner types).
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Major cracks or very sudden water loss, may result from more serious structural failure e.g. where steel reinforcement has corroded and failed due to poor original construction. Inadequate covering of the steel with concrete and the wrong concrete mix can allow the pool water (and even ground water), to gradually corrode the steel reinforcement, which is essential for strength.
Even if the pool is not leaking, evidence of significant cracking or structural movement should be investigated before further use, as pool failure can be sudden and very dangerous especially if the pool is located on a slope or set entirely above ground. Though a well built pool will tolerate some substrate movement, many pools crack when shrinkable substrates contract in very dry weather (2006 was particularly dry), heavy rain can also wash away substrates on steep slopes. Unfortunately excessive movement may well require rebuilding of the pool, but minor seasonal movement (usually only causing hairline cracking) can normally be repaired
provided that flexible products area used.
- Get an electrician to check the seals / bulbs on pool lights. Never turn these on when the pool is empty as the high temperature can cause them to explode!!!!