Tank Maintenance

GENERAL

A well designed water catchment system and quality water tank will provide a long term low maintenance system. Like most surfaces however, stainless steel does require some cleaning to remove dirt and grime to keep it in pristine condition. The level of cleaning and maintenance depends primarily on the environment.
For most locations, regular maintenance every 3-6 months is generally sufficient. Attention should be given to the below points:
  • Roof and gutters should be clean and free of debris and not hold stagnant water.
  • Clean first flush diverter regularly.
  • Keep inlet strainers clean and free of debris.
  • Inspect tank regularly to ensure there are no mosquito/bugs living inside and the screens and tank light/dust covers are working.
Following these steps will help prevent debris built-up in your tank. All tanks however eventually collect debris at some stage and EcoBright recommends that water tanks should be cleaned/flushed approximately every 3-5 years. Please note; to clean inlets strainers, do not walk on the roof of your tank, instead use a ladder or plinth spanning the tank to avoid bearing weight on the roof.

Algae or smelly water should be always be treated to ensure it is safe to drink. This can be done with products such as Davey Aquasafe Liquid Solution or using 40 mL of liquid sodium hypochlorite (12.5% available chlorine) or 7 grams of granular calcium hypochlorite per 1000 litres of water. A chlorine taste and odour may persist for a few days but this does not make the water unsafe for drinking. Stabilised chlorine should not be used.

In severe cases, completely flush the tank or use a professional tank cleaner to service your tank. For referrals in your local area please contact us.

STAINLESS STEEL SURFACE CARE (DETAILED)

The maintenance of the exterior of water tanks can be as important as the internal maintenance. While in most locations normal rain washing is sufficient to clean the outside of tanks, in more polluted or corrosive environments, such as coastal locations, stainless holds its appearance best if washed regularly.

Routine Cleaning

When washing use soap or detergent or 1% ammonia solution in warm, low chloride water with cloths or soft brushes to avoid scratching the surface. Smears will be reduced if the surface is dried afterwards. Below is a table of suggested cleaning methods for routine cleaning.
Stainless Steel Cleaning Methods
Routine cleaning will benefit stainless steel. Below is a table of suggested cleaning schedules.
Stainless Steel Maintenance Schedule
Marine Note: Discolouration or 'tea staining' most commonly can occur within 5 kilometres of the coast and becomes progressively worse closer to marine water. For situations right on the seafront, it is recommended that cleaning is performed once a month.

Grease, oily films and organic contamination

Oils and grease may be removed by alkaline formulations or hot water and detergents or, if necessary, by hydrocarbon solvents such as alcohol, acetone or thinners or eucalyptus oil. In all cases the surface should be rinsed with clean water after and preferably dried.

Adherent hard water scales and mortar

Adherents like hard (bore) water scales/deposits and dried mortar splashes may be removed chemically. Use hot 25% acetic acid (vinegar) or warm 10% phosphoric acid. Following the acid wash, the surface should be neutralised with dilute ammonia or sodium bicarbonate solution, rinsed and dried.

SURFACE RUST & TEA STAINING - REMEDIAL WORK

The brown surface stains that can occur on stainless steel are simply cosmetic rust stains. This ‘tea staining’ does not progress to potential structural damage as can occur with carbon steel. The procedures outlined below may enable the removal of tea staining, however if the progression of damage is beyond these recommendations it is advisable to employ an experienced contractor.

Early action is desirable, before the appearance of the underlying surface is changed. If the surface is pitted, then it is probable that it will require mechanical repolishing. After mechanically cleaning off tea staining, it is preferable to passivate the surface by using a nitric acid gel. Nitric acid is a strong, oxidising acid cleaner and has the added advantage that it is a passivating agent. For marine exposures, passivation is very strongly recommended.

The Nickel Institute has suggested that rust may be removed by the use of a 10% phosphoric or oxalic acid followed by a 1% ammonia solution neutralisation and then a water rinse.
Alternatively a mild acid based cleaner such as sulphamic acid (used in some saucepan cleaners) can be used with some care to avoid local changes in appearance.
There are also proprietary chemical cleaning treatments, often based on citric acid or other chelating compounds, which can remove free iron and other foreign matter.
Notes:
  • Use of liquid acids on site is generally unsatisfactory as contact time is short and the acid may run off and damage adjacent components.
  • Do not use chemicals containing chlorides, chlorine, bleaches or hypochlorites to prevent the risk of pitting corrosion. If used, promptly and thoroughly clean off.
  • Never use hydrochloric acid or sulphuric acid.
  • Do not use carbon steel brushes or wool on stainless steel, to avoid particles embedding on the surface and causing rust. Impregnated nylon pads (eg scotchbrite) or stainless steel wool are satisfactory.
Prevention of recurrence may be achieved by either: increasing the frequency of maintenance, improving the surface finish (mechanically polish and chemically treat), altering the design, improve grade selection, or the last resort (as this is irreversible) paint the s/s (lacquers and polyurethanes are generally used as top coats).
 
The above is intended as a guide only, and it must be recognised that there are risks associated with all cleaning operations. All treatments must be evaluated by the user.

For more information please refer to quality sources such as ASSDA, Atlas, Outokumpu, Austral Wright, or other industry bodies and manufacturers, or feel free to contact us.