FAQ's

WATER TANKS:

Q: Why a Steel Water Tank?
A: Poly tanks seem an attractive alternative to steel from the viewpoint of corrosion, base preparation and price. However:

- HDPE (High Density Polyethylene) is manufactured from petrochemicals. Difficult to dispose of in an environmentally/ecologically safe manner.

- Anecdotal evidence from our customers strongly suggests the smell and taste of plastic is evident in the water.

- Poor UV (Ultra Violet) resistance encourages algae growth and limits the capability of recycled plastic being used to make water tanks.

- Fire resistance is very poor.

- Steel offers good service life and is 100% recycleable.

Q: What material options can I choose from?
A:  We offer 3 material options as follows:

1) Traditional Gal:
-Tank Iron:  Curving quality iron. Base material thickness (BMT) is 0.6mm. Coating mass designation is Z600 (ie 300 g/m² (grams per metre squared) per side). 

- Base and lid: BMT 0.6mm. Coating designation Z275.

- Traditional Gal tanks have a proven history in terms of service life, water quality and appearance. They remain a popular choice for our customers, particularly in rural/semi rural areas.

2) Colorbond/Zincalume:

- Tank iron: Curving quality iron. BMT 0.6mm. Coating mass designation AZ150.

- Base and lid: BMT 0.6mm. Coating designation AZ150.

- Colorbond tanks are a popular choice due to competitive pricing, full range of Colorbond colours and good service life. The reduced coating mass is based on Zincalume steel's improved performance when compared with a  gal coating of equal thickness under the same atmospheric exposure conditions. The painted finish of Colorbond steel will provide additional barrier protection. It is for this reason that we use Colorbond material (some tank manufacturers use Zincalume) for bases and lids on our Colorbond tanks. 

3) Aquaplate:

- Tank iron: BMT 0.6mm. Coating mass designation for Gal exterior is Z450. For Colorbond exterior Z275.

- Base: BMT 0.6mm. Material used is double sided Aquaplate to provide protection from tank stand/foundation materials (eg treated woods/concrete).

- Lid: Material is Colorbond per above.

- Aquaplate looks like Colorbond or Gal, but has a food grade polymer lining on the inside of the corrugated profile. It offers more robust resistance to a wide range of water qualities, including bore water which can have high concentrations of corrosive mineral salts. It is available in Gal, Pale Eucalypt or Paperbark colours. Care must be taken to avoid exposure of tank internals to sunlight, as the Aquaplate coating is not UV (Ultra Violet light) resistant. Care must also be taken to avoid scratching/damaging the Aquaplate coating. Aquaplate tanks are significantly more expensive than Colorbond and Gal, but may be worth considering if long service life is your number one criteria, or if you live close to corrosive environments (marine/industrial).

Q: How long will my tank last?

A: There are several things worth thinking about:

1.  Zinc and Zinc alloys in immersion conditions perform best when the pH of the water is neutral. Too acidic or too alkaline will increase the rate of corrosion.

2.  Increasing temperature will also increase the rate of corrosion, so the best spot for your water tank may be in a shaded area.

3.  Roof catchment is another consideration. For example, unglazed cement tiles or unpainted Gal roofs will react to some degree with the rainwater, making it less aggressive to gal materials downstream. Conversely, glazed cement tiles or Zincalume/Colorbond/painted gal/glass/fibreglass roofs (ie inert catchments) will not react with the rainwater, so it travels downstream in its most aggressive state.

4.  As a very rough guide, corrosion rate of Zincalume in an industrial/marine atmosphere environment is around 4g/m2 per year. For full immersion conditions, we would expect to roughly double the rate of corrosion to 8g/m2 per year. If the coating mass is 150g/m2 ie 75g/m2 per side (as is the case with Zincalume), we would expect a life of around 10 years. Colorbond has the Zincalume base material, then on the outside, a conversion coating, primer coat and finish coat. On the inside there is the conversion coating and then a corrosion inhibitor/backing coat. This provides barrier protection and life expectancy is significantly better. Actual tank life however, will be subject to location, roof catchment type, water pH, heat loading, filtering/diverting strategies implemented (and regularity of maintaining them)-all of which can have a significant effect. If long service life is your main selection criteria, it may be worth the extra cost of specifying Aquaplate material.  Some customers, however, prefer non plastic/polymer coatings.

5.  Leaf diverters and 1st flush diverters are highly recommended. Leaf diverters will prevent solid contaminants from entering your tank and will keep mosquitoes out. First flush diverters will help avoid water with high concentrations of bacteria from bird/possum poo + all sorts of other potential nasties from entering your tank.  Just while we are on the topic, you will need to consider the stack height of the leaf/1st flush diverter (roughly 200mm for the leaf diverter and 150mm for the 1st flush-total ~400mm). Don't forget also a fall of around 1 in 60 is required in the storm water pipe to tank entry. It all adds up and may mean a reduced height tank is required to package everything.

6.  Care must also be taken with tank to tank connection. We have seen a new Zincalume tank (not one of ours) connected downstream from an old gal tank which had been repaired by rendering the inside with concrete. The Zincalume tank rusted to perforation stage in around 6 years. A pH check of the water in the Zinc tank indicated alkaline reading (probably due to the concrete render), with resulting reduction in tank life.

7.  Budget.

Q:  How are Steely Dam tanks sealed?

1.  We have developed robust design and build processes over 30 years in the industry. These are carefully detailed in our Operations Manual. 

2.  Where we regard a join/seam in the build process as high risk, a 2-stage silicon sealant application is undertaken. The first stage is allowed to cure prior to the second stage application.

3.  Our tanks are sealed with a neutral cure (ie it doesn't smell bad) water-potable-to-AS4020 silicon sealant, guaranteed for 25 years.

4.  Our industry standard stitching screws achieve 1,000 hrs salt spray resistance performance.

5.  Stringent inspection and sign-off processes are undertaken during the build process, at each stage of assembly. Final inspection is completed before customers are contacted that their tank is ready.

6.  We only use tank outlets cast from a non-rusting Zinc Alloy. A strong compression fitting with washers and flanges completes the assembly. Brass gate valves are not recommended for direct coupling to the Zinc Alloy tank outlets due to possible electrolysis. We recommend Chrome Plated Full Flow Ball Valves be fitted to our tanks.

Q: What fittings come with the tank as standard?

1)    All our tanks come standard with a 400mm mosquito proof inlet strainer basket (this is large enough for tank entry if required), 90 or 100mm overflow and an outlet fitting of your choice. We can also supply a full range of accessories/extras if required (CFA fire outlets, chrome plated full flow ball valves, mosquito-proof overflow screens for example, plus many others).

2)    For tanks around the 2m diameter mark and above, we fit as standard an internal prop, to ensure the tank lid has slight convexity to its surface and therefore aid water run-off. If you want a conical lid, we can do that too.

Q: What base should I put my tank on?

A: We recommend a flat, level, reinforced concrete tank base as the best option for your water tank. 20MPa concrete, 80 slump, with 25mm aggregate is what we aim for. F62 is the recommended mesh size. The slab should be 100mm thick. Most concrete companies have a minimum order quantity of 0.4m3. They will also charge a waiting time after 20 minutes, so if you plan to DIY, make sure you are ready.

For Colorbond and Gal tanks we recommend a layer of malthoid be used between concrete and the tank. This will isolate the tank from the corrosive effects of the cement. We can supply the malthoid in 1m wide strips/rolls to suit as required.

- Another base option we have seen good success with (used at the factory for our slimline tank test bed), is boxed 1/4 minus screenings. This may be a more cost effective approach-without the stress of a concrete pour. Prep work is very similar to concrete in terms of removing top soil down to firm substrate (clay). You must ensure the screenings cannot be washed away, hence the box. Use 200 x 50 or larger sleepers for same. It is critically important to ensure the finished screenings are flat and level. We avoid sliding the tank directly on the screenings during installation, as this is likely to push highs/lows into the surface. We place 2 long sleepers across the screenings, slide the tank across/rotate as required ON THE SLEEPERS and then once in position, carefully lift the tank a little to remove them-one at a time.

- We offer a full installation service including the above, so contact us for a free quote. if you want a steel tank stand, these must be Engineered and installed by appropriately qualified consultants.

Curly Ones:

Sometimes access to the tank site is difficult, making tank delivery/installation impossible. Whilst not a preferred option, we have assembled tanks in backyards to get around access/powerline issues.

Your tank is in good nick but the lid has failed? Yep, we can install a new one. Subject to tank size, location, difficulty of access etc, the cost is around $1,200 for a 3.0m diameter tank. The cost includes installation of a lid prop.

GARDEN BEDS:

Q: What material options can I choose from?

A:  We offer 2 material options as follows:

Gal iron and Colorbond/Zincalume.  If traditional corrugated iron is the look you are after, gal material may suit best. The Colorbond beds can be made in any current Colorbond colour.

(Aquaplate is typically not used, as the polymer coating is not resistant to UV light and will degrade by embrittlement)

Q: How long will my garden bed last?

A: As a rough guide, if the rate of corrosion is assumed at 8gm/m2 per year and the material coating mass is 150g/m2 (ie 75g/m2 per side, as is the case with Zincalume), we would expect a life of around 10 years. Soil Ph near neutral (6.5~7.0) will maximize bed life. If long service life is a key criteria, we recommend painting the inside of the bed with a brushable, food-grade, rubber based waterproofer. 2 coats are required for best results and the amount of water proofer required will depend on the bed size.

Q: Does my garden bed come with a rubber edging strip to cover the top sharp edge?

A: No. Your Ark Sheetmetal garden bed comes with a professionally turned over safety fold, that cannot be displaced or damaged and leave the edge exposed and you at risk. It also comes with a stiffening fold along the bottom edge.

Q: Do the oblong-shaped garden beds need reinforcing along the flat sides?

A: Yes, subject to the bed size. We will advise if stiffening struts are required. Cost for factory assembly is $35 per strut.

Q: What size garden bed can I have?

A: Standard heights are 410mm, 600mm and 820mm, but we are happy to supply anything in between. Round or oblong/slimline shaped beds can be manufactured to our standard sizes, or your custom requirements. It is worth remembering that the larger/deeper the bed, the more soil will be required to fill it.

Q: What should I put in the beds?

A: General garden rubble (broken bricks/concrete etc) can be neatly hidden at the bottom of your garden bed-this will also help with drainage. On top of this our tip would be an organic soil topped with a mulch of straw.