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Why should I change to hth?

Changing to hth is easy. Many pools in both soft and hard water areas, have successfully changed to hth for the unique benefits and savings that it brings. With a range of products & pack sizes to suit all pools and any plant room situation, hth is widely used in the smallest spa pool and water play feature right up to 50m pools and large lidos.

Use our calculator below to see how much you could save if you are currently using Sodium Hypochlorite.

Approximate costs for a gas heated pool running on Sodium Hypochlorite

Water used for each backwash m3
Pool temperature degrees C
Backwashes per week
Water thrown away per week to maintain TDS levels m3
Deliveries of chemical per year
Carbon footprint:  kg
Typical gas costs per year: £ 
Typical water costs per year: £ 

Approximate cost savings for the same pool running on hth

Expected deliveries of hth per yearSaving  %
Carbon footprint  kg Saving  %
Typical gas costs per year £Saving  %
Typical water costs per year £Saving  %
Approximate total saved on annual gas and water bills £Saving  %

These figures are based on 1kw/h of gas costing £0.06 and water costs of £1.00 /m3 to purchase and £2.00 /m3 sewerage costs. Assumptions have to be made on the efficiency of the boiler - for an average gas fired boiler within a facility it takes around 1.2 kw/h to heat up 1m3 of water by 1oC, with the average temperature of incoming mains water 10oC.

These are approximate costs / savings and for a more detailed view on your current operation please contact the technical services team who can provide a free no obligation site survey


Usually a conversion can be achieved for less than the cost of a new bulk storage hypochlorite tank and wherever possible, existing equipment is utilised.

hth Dosing - Pump and Tank system

Figs 1 & 2 - A basic pump and tank system - similar to that used for dosing sodium hypochlorite.

Site surveys by Lonza personnel identify existing equipment that can be utilised to dose hth. Wherever possible existing pumps are redeployed, for example, using the main pool dosing pump on a small pool if appropriate. However the tank itself is usually increased in size, resulting in less frequent recharging. If briquettes are to be used, a suspension net is required which Lonza can provide free of charge, see Fig 2.

Pools remain fully operational during the installation of any type of preferred dosing system.

hth Dosing - Dedicated Feeders

Dedicated feeders are ideal for sites which require minimal operator involvement, as they offer both safety and convenient dosing. There are several feeders which are capable of dosing two pools independently - again bringing down the cost of conversion.

Lonza Technical Services offer a free and no obligation site survey where we will identify your specific requirements and advise on the feeders most appropriate for your site from the Lonza Easiflo® feeder range