I don't know. All we get is warm water, though our winters are chilly which might make a difference. I used a lot of this seaweed at my last home and the soil was greatly improved. The soil is sandy and rocky here and tropical storms tend to wash all the topsoil back to the sea. As I added lots of local seaweed more of the rain soaked into the soil, rather than running down to the river/sea.
I've no idea how mineral contents compare.
Tony and stood in the back yard today and admired all our plants. Citrus, mangoes, dragonfruit, one large (and blooming) schotia to be followed by a flame tree or two. There were two almost-dead trees here when I moved in. I am happy with what we have accomplished, happy we have a lot we can share now and really happy that the land will go to Tony and his family when I'm gone.
I've ordered a lot of tomato seeds. My goal is to have locally grown tomatoes here year-round. Almost all that we get now are typical store-bought. We know lots of gardeners so I think we can get an informal cooperative going. Besides being perhaps the best home-grown vegetable (I know, its' a fruit - never mind) for our use, Americans who are where will be happy to pay for them. My gac fruit plants are growing well. I've never had them but have been told they can be added to most any tomato dish and will up the nutritional content considerably.
And, as of yesterday, I have a lot of little golden gardenia plants sprouting.
katie