In such a competitive field as ballast water treatment systems, it is accepted that every type approval will be examined by competitors to search for any conditions of approval which may give them an advantage over their own products or a seeming disadvantage that could be exploited in the market. It seems that some questions over the approval were sent to the US Coast Guard which, in the interest of transparency, has chosen to make public the questions and their response in one of its blogs. The questions and the USCG answers are shown below: 1. **Why is Echoclor permitted a 0.2mg/L MADC when clearly the rule is 0.1mg/L?** Table 3 of the 2013 VGP identifies the maximum ballast water effluent limits for residual biocides in discharged ballast water. There is a difference between chlorine dioxide, where the maximum allowable discharge concentration (MADC) is 200 micrograms/L (0.2 mg/L) and chlorine which has an MADC of 100 micrograms/L (0.1 mg/L). 2. **Does the decreased dose from 5 to 4.25 affect the IMO TAC?** The USCG Type approval certificate (TAC) is separate from the IMO TAC. The Coast Guard cannot comment on what effect the US type approval might have on certificates issued under the Ballast Water Management Convention. The second question is particularly interesting as it suggests that the two approval processes put different operating parameters on ballast treatment systems. That could lead to problems with port state control inspectors if the wrong parameter was used inadvertently by crew on board so it may be something that owners will need to somehow ensure does not happen. (link: https://shipinsight.com/guides/in-depth-guide-to-ballast-water-treatment text: Read more about ballast water in our in-depth guide).