Steps to take when bringing the pool back into service



All too often, the pool operator is short of time when bringing the pool back into service. However, this is a decisive stage in correctly treating water during the season.

By dedicating a little more time at the start, you will come to realise that the season will pass without any major problems, that the individual will get greater enjoyment out of their tank and, finally, that the word "pool" will become synonymous with "well-being" and that its upkeep during the season will no longer be regarded as a constraint.

Indeed, if the pool is correctly brought back into service, 95% of the treatment effectiveness will be covered for the season. In other words, 95% treatment effectiveness equates to:

• 95% fewer problems during the season

• 95% client satisfaction

• A lot of maintenance time saved during the season

• All products used will be effective

• Large saving on treatment products

What does this 95% correspond to?

The 95% treatment effectiveness is linked to:

• The filtration group (pump + filter): 80 %

• Water balancing: 15 %

The filtration group

The filtration group plays a multifaceted role:

• Suck up any water impurities through the skimmers and main drain and retain them in the filter: to produce "clean" water at the filter outlet

• Cause the water to mix and therefore prevent it from stagnating

• Produce streams of water to slow down the settling of algae and enable treatments to be better distributed throughout the tank

However, as the filter retains the dirt of the water, it will gradually become saturated and the water circulation will progressively be cut off.

The pressure in the filter therefore increases, meaning that the water finds it difficult to pass through the filter.

The effects of this increase in pressure will be two-fold:

• Increase the electric consumption of the pump

• Loss of flow after the filter.

If the former increases the electricity bill and ages the pump, the latter will reduce the water mixing process which will generate cloudy water and increase the settling and attachment of algae in the tank.

As the filter is "dirty", all this dirt will be attacked by the chlorine (or other kind of disinfectant) present in the water. A significant reduction in the chlorine rate in the tank will ensue; there will be an increased consumption of chlorine during the season and the feeling of the individual that his/her treatment is ineffective will grow!

That's why special attention should be paid to the filter and the operation of the pump, in order to guarantee healthy bases, by providing the client with the filter cleaning recommendations: clean just before the saturation pressure is reached.

Water balancing

The water balance represents 15% of the treatment effectiveness, as it guarantees a stable pH and will limit the limescale deposits or attacks on the coatings (stains, wrinkles, corrosion points, etc.).

A well balanced water with a pH in the comfort zone of the swimmer (between 7.0 and 7.4), will guarantee that the coating ages well and that users will be treated to a pleasant bathing experience (red eyes and itching are a thing of the past!)

The water balance is governed by 3 key parameters: PH, alkalinity and calcium hardness. If the values of these three parameters are perfectly in tune with each other, the water will be clear, non-aggressive and non-scaly and the pH will be stable.


pH (potential hydrogen) is the key to successfully treating water. The water is characterised by a pH generally between pH 7 and pH 8 (over a graduated scale from pH 0 to pH 14, the pH expresses the acidic or basis nature).

- Between 0 and 6.9, the water is deemed to be acidic

- At 7.0, the water is deemed to be neutral.

- Between 7 and 14, the water is deemed to be basic

In pools, the optimum pH is 7.2 (corresponding to the pH of lachrymal fluid).

Water is naturally laden with dissolved elements, calcium and magnesium salts, which impact both on the balance and stability of its pH. PH regulations involve acidic or basic products, conditioned as powders or liquids.

_As powders: the regulators pH minus and pH plus are recommended for their safe use.

_As liquids: these regulators, designed for automatic metering units, are admittedly more potent. On the other hand, their use is more restrictive.

In practice, the more "alkaline" that water is deemed to be (strongly laden with carbonates and bicarbonates), the more difficult it is to sustainably modify its pH using acidic regulators.

Water alkalinity

Water alkalinity, or its total alkali strength (TAS), characterises the buffering power of the water, i.e. the capacity of an acidic or basic product to impact on the pH of the water. The higher the TAS, the more difficult it is to change the pH of the water. In general, the TAS should be between 10°f and 25°f (1°f = 10 mg/L of CaCO3).

The TAS value is increased by adding the product Acti Alcafix (sodium bicarbonate based) and is reduced by adding Acti pH minus (liquid or powder).

The Total Hardness of water (water hardness)

The Total Hardness (TH) of water is determined by the concentration of calcium (Ca++) and magnesium (Mg++) ions. Water is deemed to be soft if its TH is less than 10°f (1°f = 10 mg/L of CaCO3). It is deemed to be hard if its TH is greater than 35°f. It is important to maintain the TH at a value of approximately 20°f.

The TH value is increased by adding the product Acti TH Plus (calcium chloride based).

To lower the TH, a process to remove carbon dioxide is required and this is not a simple task.

It is possible to stabilise limescale (TH) by adding the product Acti Scale remover.


Parameters of water balance and associated products

The Taylor Table

The Taylor table shows whether the water is balanced and makes it possible to adjust the three parameters (TAS, pH, TH) to obtain this balance with a balancing pH value of 7.2.

This table is very straightforward to use. All you have to do is measure the value of the TAS, the pH and the TH and check them against the table.

_If its 3 points are in line, that means that the water is balanced.

_Otherwise, the water will have to be balanced.

Steps to take to balance water with a pH of 7.2:

1) Check the TH value.

If it is less than 200 mg/l , increase its value up to 200 mg/l.

Otherwise, maintain its value (it is very difficult to reduce the TH value).

2) Mark a point on the pH scale at 7.2 and trace a straight line passing through the TH value and pH = 7.2.

3) This straight line cuts through the TAS scale, thereby giving its ideal value for guaranteeing that the water is balanced.

4) Make the TAS adjustments according to the ideal value found (increase or reduce the TAS to obtain this value)

5) Adjust the pH to 7.2.


[caption id="attachment_5510" align="aligncenter" width="300"]Taylor Table Taylor Table[/caption]

Taylor Table

It is therefore essential to make sure that the water is properly balanced (pH, TAS and TH) to maintain the healthy state of the water (non-aggressive and non-scaly) by promoting the optimum action of the disinfectant used.

You are urged to check the pH and the disinfectant rate at least once a week.

Check the TAS and TH when the pool is made available for use in order to modify the parameters, if necessary, and once or twice during the season.

You will finally notice that limescale deposits favour high water temperatures, meaning that Acti Scale remover will be required.

Comprehensive cleaning

Comprehensive cleaning involves cleaning of the tank and also thoroughly cleaning the filter (scale removal).

Verification of the filtration group

The filtration group has a significant role to play in water treatment. It represents 80% of treatment effectiveness.

Before any cleaning operation during the process to bring the pool back into service, make sure that the pump is working properly and that the filter has not been damaged over winter. As 80% of the treatment is guaranteed by the filtration group, it is essential that these items operate at optimum level.

Comprehensively cleaning the filter (scale removal)

This is a decisive action as it will remove all the limescale which was blocking the passage of water and causing high pressure in the filter, and therefore loss of flows.

To guarantee that your filter operates at optimum level:

_Perform a backwash once every 10 to 15 days (in keeping with the internal filter pressure).

_Perform regular and comprehensive cleaning/limescale removal operations (once every 1 or 2 months and with the tank open).

With that in mind, SCP recommends the product: ACTI Filter cleaner.

ACTI Filter cleaner:

Specially designed formulation for all filter components: elimination of scale deposits, rust, etc. and generally all deposits of a mineral origin present in the filter medium.

Directions for use:

- 1 litre for 75kg of sand for family pools, for "quick sand" filters.

- 1 litre for 100kg of sand for communal pools, for "slow" filters.

- Backwash the filter and then rinse.

- Introduce the product upstream of the filter (skimmer, spout or pre-filter), start up the filter for a few seconds in the "drain rinsing" position to spread the product throughout the filter until the colouring appears in the indicator light.

- Allow to act for at least twelve hours, or even overnight.

- Backwash and thoroughly rinse the filter until the colouring has completely disappeared.

NB: Although more restrictive, the best method, however, consists of pouring the product directly into the open filter on the sand, after taking the precaution of bringing the water level to the sand level and closing all valves.

Why change the sand of the filter?

The sand of the filter inevitably wears out. When it is new, the sand has grains whose size and outline are clearly defined. During its use and whenever a backwash operation is performed, the grains smooth out under the effect of the circulation of water and get smaller and smaller. Therefore, it is necessary to change the filter mass every 5 years approximately.

Cleaning the tank

Its role is a simple one: destroy and remove any pollution that has accumulated over winter. With that in mind, you should make sure that all the dirt is removed from the tank and that the water line, canvas sheet, roller blind and shelters are cleaned to limit the pollution during the season.

Use products suited to pools (Acti Net’bord gel, Acti water line cleaner), which will be less destructive over the long term than pure acids or ground acid detergents which are available on the market.

Cleaning the edges

It is no use to have a supremely clean tank if the surrounding areas (edges + bands) are dirty...Dedicate a little time to the cleaning of the edges and bands to remove any pollution that has built up over winter, and prevent a significant build-up of germs throughout the season.


All too often, the water in your tank is cloudy even when the parameters governing the water balance are showing correct values. That is due to the presence of tiny suspended particles. The use of a flocculating agent is therefore essential to turn your water crystal clear again.

Why Flocculate?

Contaminants in pool waters can be categorised in keeping with the size of their particles or their consistency. The bigger a particle is, the easier it will be to filter. On the other hand, small particles will pass through the filter. Therefore, a filter with a low filtration rating will enable tiny particles to be filtered.

Sand filters have a filtration rating between 20 and 50 µm. Therefore, particles smaller than 20µm will not be retained by this kind of filter. These particles are almost always organic matter, and when they are not trapped in the filter, they can slow down the disinfection process. It is therefore necessary to increase their size in order to trap them in the filter: this is what the flocculation process is all about.

Flocculating agents destabilise the electric charges of small particles and pack them together. When they are gathered together, their size increases so that they can be retained in the filter


Simplified diagram of a sand filter with and without flocculating agent

Metal ions, colloidal pollutants and micro-organisms can therefore be effectively eliminated and removed from pool waters.

The result is clear water which is more crystalline and which makes it easier to clean the pool and saves on disinfectant.

NB: It is important to know that some kinds of micro-organisms are even resistant to disinfectants. The only way to get rid of them is by combining flocculation and filtration. That is why a flocculating agent should be used in public pools which have sand filters.

How to flocculate?

To achieve a high filtration quality associated with flocculation, particular parameters have to be observed.

Recommended Value Parameters

Values of recommended parameters when using flocculating agent

Manual use

For improved filtration, SCP has created a "Flocculating Agent Pad".

Placed in the skimmers or in the pre-filter of the pump, the Acti Flocculating agent pad progressively releases its flocculating agents and helps to improve filtration while clearing up the pool water. Furthermore, as it acts progressively, the flocculating agent cartridge prevents the formation of suspended particles and removes any that are already present.

Flocculating agent cartridges:

On account of its formula and its pre-dosed format, the Flocculating pad increases the filtration fineness, clarifies the pool water and improves disinfection.

The flocculating pad is therefore ideal for all sand filters.

Directions for use:

Use one pad per 25m3 and place it in the pre-filter of the pump or in the skimmer after the filter has been washed. Set the pH between 7.0 and 7.4. Repeat every 10 to 15 days.

Nb.: flocculation is a process that can also be carried out on a regular basis owing to the flocculating powder product. All you have to do is set the pH between 7.0 and 7.4 and pour in 200g/10m3 of water to be treated directly in the tank skimmer.

Automated use (recommended for communal pools)

In view of the significant volume of the tanks and filtering components, you are recommended to use an automated installation in order to guarantee maximum comfort for all swimmers. This kind of system effectively tackles the considerable amount of particles left behind by swimmers.

With this in mind, SCP has developed Flocculating Liquid; this concentrated product has been specially designed for use in a metering pump. Due to its high concentration, Acti Flocculating liquid guarantees crystal-clear water at all times. Its packaging (in a 1-20 l can) promotes significant autonomy meaning that regular handling operations are not required.

ACTI Flocculating liquid:

Easy to use due to its concentrated and pre-hydrolysed formula which has been specially designed for use in communal pools.

Acti flocculating liquid is therefore ideal for all communal pools with sand filters.

Directions for use:

The flocculating agent is continuously injected by metering pump after the pump pre-filter and in front of the sand filter, directly from the can.

The permanent injection varies according to the frequency and environment of the tank.

Quantity of pure Acti flocculating liquid used per day of route application.

Nb 1: The injection point of the flocculating agent should be placed after the pre-filter of the pump and in front of the sand pump. On account of the speed of the flocculating process, you should make sure that the mixture between the flocculating agent and the water at the injection point is sufficient. This can be modified for instance by extending the diameter of the pipe at the injection point and by increasing the mixture time by at least 5 to 10 seconds before reaching the filter.

Nb. 2: the flocculating agent should not be applied only in combination with a slow to average filtration speed and also with a particular height of the filter layer.



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