A brand-neutral tender specification for polyphosphate media is built around three things: the function the medium must perform, the water conditions it will meet, and acceptance criteria that can be verified by test or document review. Trade names such as Siliphos are useful as a reference point, but if they appear as a mandatory requirement, the tender effectively specifies one supply chain and removes your ability to compare offers. The practical fix is to describe the material by its intended behaviour and its measurable properties, then allow named products only as examples of an acceptable type — with evidence required from every bidder.
Start by agreeing what the medium is expected to do
Polyphosphate media is frequently specified in the wrong category. Before writing a single clause, separate the functions. This matters because a bidder who reads “water treatment” without qualification may quote a softener, a filter cartridge, or a dosing system instead of the medium you actually want.
| Function | What it means | Is slowly dissolving polyphosphate media the right answer? |
|---|---|---|
| Scale inhibition | Limits the formation of new mineral deposits on pipe and heat-transfer surfaces | Commonly the intended use; usually described as threshold treatment |
| Corrosion inhibition | Forms a thin protective film on metal surfaces, particularly in distribution pipework | Often a secondary objective of the same medium |
| Sequestration | Keeps certain dissolved metals in solution so they do not precipitate | May be relevant depending on the specific material |
| Water softening | Removes calcium and magnesium ions from the water | No — this requires ion exchange or another removal process |
| Filtration | Removes suspended particles | No — the medium dissolves; it does not act as a filter bed |
| Scale removal | Removes deposits already present | No — prevention and removal are different processes |
| Disinfection | Inactivates microorganisms | No — never specify a phosphate medium for microbiological control |
Note also that “polyphosphate media”, “phosphate crystal”, and “silicate-phosphate crystal” are not automatically interchangeable terms. Products sold under these labels can differ in chemistry, dissolution behaviour, and regulatory status. A specification that treats them as identical will produce bids that are technically non-comparable even though they look the same on paper.
Why brand names weaken the document
Siliphos is a trade name that has become widely used in tendering as a generic shorthand for a slowly dissolving polyphosphate-type medium. That creates two problems. First, different suppliers may attach the name to materials with different dissolution characteristics and different approvals. Second, writing “Siliphos or equivalent” without defining what “equivalent” means gives evaluators no objective basis for accepting or rejecting an alternative — so the clause is either ignored or applied arbitrarily.
A neutral specification does not ban the name. It demotes it: the trade name becomes an example of an acceptable product type, while the binding requirements sit in the performance, physical, and documentation clauses.
The clause structure of a workable neutral specification
| Clause | What it should state | What to avoid |
|---|---|---|
| Purpose | The treatment objective in functional terms (for example, limiting new carbonate scale in a potable water line) | General phrases such as “for water treatment” |
| Source-water basis | The water analysis the design assumes, with sampling point and date | Leaving water chemistry to the bidder to guess |
| Material description | The material type and form, described by behaviour rather than brand | Naming a single manufacturer’s product as mandatory |
| Physical properties | Form, nominal dimensions, fill or bulk quantity, packaging unit | Copying a datasheet figure you have not verified |
| Equipment interface | Housing, cartridge, or vessel type the medium must fit | Assuming the bidder knows your installed equipment |
| Water-contact status | Required regulatory position for the destination market | Treating “food grade” as proof of potable-water suitability |
| Verification | Documents, samples, or tests that must be submitted and how they will be judged | Accepting marketing literature as the sole evidence |
| Equivalence | The process by which an alternative product is accepted | “Or equivalent” with no stated criteria |
| Documentation | Safety data sheet, technical data sheet, batch identification, shelf-life statement | Requiring certificates the supplier may not lawfully hold for your market |
Writing the material description without brand lock-in
A neutral description identifies the material family and the required behaviour, then sets out the evidence that demonstrates it. For example, rather than naming a product, the clause might require “a slowly dissolving polyphosphate-based medium intended for continuous contact with flowing water, supplied in a form suitable for installation in the specified housing, and supported by the manufacturer’s dissolution and water-contact documentation.”
Every number in that clause — dissolution rate, life expectancy, allowable temperature, allowable pH, maximum flow — must come from verified data for the specific product being offered. Do not transfer figures from one supplier’s datasheet to another product, and do not write plausible-looking values into the tender to “give bidders a target”. Invented limits either exclude compliant products or force bidders to quote against numbers nobody can meet.
Setting the source-water baseline
Polyphosphate media performance depends heavily on the water it contacts. If the tender does not state the assumed water quality, each bidder will design against different assumptions. Include at minimum: hardness, alkalinity, pH range, temperature range, iron and manganese where relevant, and expected flow or daily volume. State whether the analysis is a single sample or a seasonal range, and identify any planned changes to the source.
Handling the potable-water question correctly
If the medium will contact drinking water, the specification must require evidence that the exact product is accepted for that use in the destination market. “Food grade” describes a material’s suitability for food-contact applications in a general sense; it is not by itself an approval for drinking-water contact, and the applicable scheme differs by country. State the market, state the required approval or listing, and require the document to name the product and the manufacturing site. If you do not yet know which approval applies, write the clause as an item to be confirmed with your regulatory adviser before the tender is issued rather than assuming one.
Turning brand-specific text into neutral text
| Weak phrasing | Stronger neutral phrasing |
|---|---|
| “Siliphos crystal, 100% original” | “Slowly dissolving polyphosphate-based medium; products of this type may include silicate-phosphate crystals offered under trade names” |
| “Must last 12 months” | “Supplier shall state expected service life and the conditions on which it is based” |
| “Food grade approved” | “Product shall hold the water-contact approval required in [market]; documentation naming the product and site shall be provided” |
| “Same as Brand X” | “Equivalent products shall be substantiated against the performance and documentation clauses of this specification” |
| “Dosage 3–5 ppm” | “Supplier shall propose a dose range with supporting method and rationale based on the stated source-water analysis” |
The pattern is consistent: replace an assertion with a requirement to state, substantiate, or document. That keeps the specification open while making the comparison rigorous.
Keeping evaluation genuinely competitive
Neutral wording in the specification can still be undone by the evaluation criteria. Three practices help:
- Require the same test method. If two bidders report dissolution or life expectancy from different methods, the figures are not comparable. Ask each bidder to name the method and the conditions.
- Score substantiation, not adjectives. Weight the quality of the supporting documentation alongside the claimed performance.
- Define the equivalence route in advance. State who reviews an alternative, what evidence is required, and the deadline for submission. An equivalence clause with no process becomes a dispute after award.
It is also worth checking discharge or environmental constraints at the point of use. Polyphosphate media introduces phosphate into the water; some sites or municipalities limit phosphorus in discharge. Confirm whether this applies to your project before finalising the treatment approach.
Pre-issue checklist
- Is the treatment objective stated as a function (scale inhibition, corrosion control, or another defined goal) rather than a product name?
- Is the assumed source-water analysis attached, with sampling point and date?
- Is every numeric limit traceable to a verified source or marked as “to be confirmed”?
- Has the term “food grade” been replaced with the specific water-contact requirement for the destination market?
- Does the document explain how an equivalent product will be assessed?
- Have you asked for the documents you will actually need at handover — data sheet, safety data sheet, batch identification, handling instructions?
- Have you avoided specifying a trademarked product as the only acceptable offer?
If you can answer yes to all seven, the tender will attract comparable bids and give you a defensible basis for the award decision.
Frequently asked questions
Can I mention Siliphos in a neutral specification?
Yes, as a reference example. Write it as “products of this type, which may be marketed under trade names such as Siliphos” and make the binding requirements functional and documentary. A named product should never be the only acceptable offer.
Is polyphosphate media the same as a water softener?
No. Softening removes hardness ions from the water through ion exchange or a similar separation process. Polyphosphate media works at low concentration to limit new scale formation and, in many applications, to support corrosion control. They are different treatments with different outcomes.
Does a food-grade declaration make a medium suitable for drinking water?
Not automatically. Drinking-water contact suitability depends on the exact product, the application conditions, and the rules of the destination market. Require documentation that names the product and the manufacturing site, and confirm the applicable scheme for your market.
How should I compare dissolution rates between suppliers?
Ask every bidder to state the test method, the water conditions, and the temperature used. Figures produced by different methods are not directly comparable, and a lower or higher number is not automatically better without the conditions attached.
What if I do not yet know my water chemistry?
Then the tender is not ready to issue. Either complete a water analysis first, or issue the document as a request for information with the analysis listed as a prerequisite, so bidders do not design against assumptions you cannot confirm.
Requesting a specification review or quotation
If you are drafting a tender for polyphosphate media and want the material clauses checked against your application, ENVO CHEMICAL can review the technical requirements with you. To make that useful rather than generic, include the intended treatment objective, your source-water analysis, the equipment or housing the medium must fit, any required specification or approval for the destination market, the estimated quantity, and the delivery country. Those six items are usually enough to tell whether your specification is genuinely brand-neutral or has quietly narrowed to a single supplier.
