I used to eat the sea lettuce from my tank. No I'll effects, and it was delicious!
Then I got spooked by zoa palytoxins, even though I have Z. sociatus, which has little to no toxin. I doesn't hurt the clowns, anyway, when they chew the tentacles off their host colony.
Dino also gives me cause to stay away. Even though I won the battle going the natural route, I know it could still be living in there in small populations.
I don't see a problem with synthetic sea water. There isn't anything in it that isn't also in the ocean.
Also, we eat vegetables that are grown in fertilizer made from poop all the time. We just wash it off.
I'm sort of in this camp.
I have eaten Caulerpa racemosa and Gracilaria from my tank, in very small quantities (basically experimental). Those species of algae are eaten, I'm Asian and I like this stuff, so why not?
THAT SAID:
I did a search here on R2R years ago and remember a thread where @Randy Holmes-Farley specifically recommended you NOT do this; IIRC it had to do with elevated levels of bacteria and contaminants in a tank, but that's just IIRC.
Would appreciate any input from him, @AlgaeBarn , or anyone else who's done this commercially, to include in what respect commercial-scale macroalgae cultivation may differ from harvesting from your 'fuge.
I also did some googling (and will do more):
1. apparently at least commercially maricultured seaweed (wakame) is cultivated in the ocean (who knows what kinds of contaminants are in the local water). After harvest:
Sporophylls are frozen immediately, while the remaining parts are bathed in hot water (85–95 °C) for approximately 20–60 seconds. The cooked plants are then thoroughly salted. The salted plants are packed in bags and pressed with heavy objects overnight to remove the excess salt water. Thereafter, the midribs and blades are separated manually by hand, packed into boxes and stored between -5 and -15 °C.
How to Farm Wakame (Undaria pinnatifida) Seaweed
This guide from the FAO Cultured Aquatic Species Information Programme provides information on farming Wakame (Undaria pinnatifida) seaweed.
thefishsite.com
Which probably does a number on bacteria and the like.
or alternately:
Pacific Harvest is proud to offer a clean, ethically harvested wakame, which is a dark khaki colour, and often has a lot of white powder* on the leaf. It is harvested from the ocean, where it grows on made-made structures such as muscle lines, then air dried and tested for contaminants.
7 Easy, Delicious Ways To Use Wakame Seaweed
The culinary versatility of wakame is endless. Learn more about it and discover our top 7 favourite ways to use wakame seaweed in everyday meals, as well as a few tips and tricks to get the best from it.
pacificharvest.co.nz
2. commercial aquaculture of tilapia (which is really a cichlid) apparently tastes better and cleaner than wild ones because they are raised and harvested in relatively clean water.
Much of the tilapia that people eat on the mainland and elsewhere is farm raised. The water in such places is often much cleaner than in places where tilapia thrives in the wild. Raised in places that use proper aquaculture techniques, the tilapia has a much cleaner taste. The meat of the tilapia is white and flaky and doesn’t have what some people say is a fishy taste.
What's Wrong with the Tilapia in Hawaii? Find Out Here.
The tilapia is a popular fish to eat worldwide. But somehow the tilapia in Hawaii doesn't enjoy the same reputation. Find out why here.
www.airtohawaii.com
(as an aside, it is invasive in Hawaii and even can be found on some reefs as they are brackish fish and move out into the ocean. That said, i can't imagine they are very well suited to the open ocean)
ALL THAT SAID:
1. I'm not eating my-tank-grown macroalgae until I'm convinced it's safe.
2. I have a hard time ethically justifying the idea that if it's not safe for me that I'd subject my fish to the same conditions.
3. SO, something of interest to me is seeing what I could do to potentially make my fuge macroalgae (Gracilaria, C. racemosa, etc.) safe to eat, whether i actually do so or not.