ATMP (aminotri(methylenephosphonic acid)) 50% and HEDP (hydroxyethylidene diphosphonic acid) 50% are two common organic phosphonic acid scale inhibitors and corrosion inhibitors. They can be used in combination, but the following points should be noted:

1. Compatibility of compounding
ATMP and HEDP are both organic phosphonic acids with good scale inhibition, dispersion and metal ion chelation capabilities. They can generally be used in combination and may produce synergistic effects. ATMP is mainly used to inhibit calcium carbonate scale, while HEDP has a good control effect on iron oxide scale and calcium carbonate scale. After compounding, it can enhance the overall scale inhibition and corrosion inhibition ability.

2. Compounding ratio
Generally speaking, the ratio of ATMP to HEDP can be adjusted according to water quality and application requirements. The common ratio is 1:1 or 2:1 (ATMP:HEDP).
If the calcium carbonate content in the water is high, the proportion of ATMP can be increased;
If better corrosion inhibition is required, the proportion of HEDP can be appropriately increased.

3. pH and stability
ATMP and HEDP are more stable in acidic environments, but too low pH may lead to increased corrosiveness. Usually the pH of the compound solution is controlled between 2 and 4, and can be adjusted appropriately with NaOH.
Avoid direct contact with high concentrations of metal ions (such as Fe³⁺, Ca²⁺, Mg²⁺) during compounding to prevent precipitation or affect the use effect.

4. Compound application areas
ATMP and HEDP can be used for:
Circulating cooling water system (power plant, steel plant, central air conditioning, etc.)
Oil field water injection system
Boiler water treatment
Industrial cleaning agent (scaling removal, metal protection)