The manuscript assesses the impact of alkalinity addition via different methods (NaOH, CaO, and bicarbonate+calcium to simulate accelerated limestone weathering) on the organic and inorganic carbon partition. The study was conducted using bottle incubations in Los Angeles Harbor, with effects of additions at different concentrations being measured for about 4 days. In general, the study is well designed, and the figures reflect the results discussed. I missed some discussion on the limitations of the study in addressing possible detrimental effects to the ecosystem throughout the manuscript, but this was added to the discussion in a clear way. There are a few points in the manuscript that require clarification of some rewriting, as pointed out in the specific comments below. Authors sometimes compare two different carbon variables assuming the reader will know why that comparison is being made, which might not be the case especially for an mCDR related publication that can attract readers outside of the ocean carbon scientific community.  Some general interpretation on what results mean throughout the results section and pointers on how it will be added to the discussion would be useful as well, for example pointing to potential impacts on biology in section 3.3.1.

In general, however, the manuscript is well written and adds useful information to the much needed and mounting literature assessing the impact of alkalinity additions on water chemistry and on biology. With some relatively minor reviews, it should be ready for publication.

L40: Needs reference

L42: Also worth discussing other impacts of dissolving all calcium carbonate

L43: I would add a “potentially” here

Table 1: All salinities were exactly 35?

L140: Consider adding equations here

L165-167: I would rephrase or add more information here, as is it reads like a preemptive rebuttal of criticism without offering arguments. Adding some information on which aspects are desirable would be more helpful.

L186-187: All bottles got the 13C tracer?

L304-307: This was a bit confusing to read. Would be less so to say both POC and DOC change, and explain why you are comparing these two variables

L355: Consider adding the date to the subtitle here as well

L446-447: Where did you get these numbers from?

L448-450: Consider rephrasing. The first sentence says there was no change, and the following one starts with DIC decrease. In general good to be more clear about which experiments you are talking about throughout the manuscript.

L463-464: as seen/assessed where/how?

L509: how quickly?

L514: Can you add another sentence or two on the ranges and setups of these experiments?

L541: How are you assessing negative impact? This is quite a broad term.

L568: Was not reproduced?

Dear authors,

Please find attached my review.

Kind regards.