Yes, there is such a thing as fake sea moss often referred to as pool grown. There are two types of fake sea moss, both of which are commercially grown. Whilst the first is grown in large pools, the second is ocean-farmed.

Real sea moss is a wild-crafted variety that grows in the ocean. It is the healthiest type available and delivers many benefits to those who consume it. Not only does it act as a prebiotic for your gut, getting rid of bad bacteria and allowing the good bacteria to thrive, but it contains a lot of nutrients too. It develops when it comes into contact with the ocean’s properties.
For example, it gets nutrients from the rocks, sunshine, and air and also grows as it moves with the current of the water. Those who purchase real moss, access many more minerals.
Pool-grown moss, on the other hand, does not grow naturally. Instead, it is produced in large tanks and is supplemented with table salt or synthetic salt rather than the salt from the sea.
Growth begins when the sea moss is removed from the ocean and then added to the tanks, those who grow it then try to replicate the conditions of the environment in which it would naturally grow. For example, they supply a constant motion to the water in an attempt to emulate the movement of the ocean's current.
Despite efforts to try and grow it in a way that is somewhat similar to the natural environment in which real moss is found, pool-grown sea moss doesn’t have the same mineral or nutritional properties.
As implied, ocean-farmed sea moss is grown in the ocean, however, the conditions and way in which it is grown are not completely natural. Whilst real sea moss grows on the rocks in the ocean, this type of sea moss is grown on ropes. Despite this, it does still have some nutritional value.
How can you tell fake sea moss?
There are several ways of identifying fake sea moss varieties. One of the most noticeable differences between real sea moss and fake sea moss can be seen through its appearance.
Fake sea moss is typically of a similar size, shape, and thickness. Real sea moss on the other hand will vary in size and thickness because of how it is grown. This is because, in the ocean, it provides a food source for marine life so you may notice that there are idents or nobbly sections where it has been nibbled on.
The color also offers a way of differentiating between real sea moss and fake sea moss. Real sea moss tends to be darker toned and typically purple, dark tan, or green in color. When exposed to the correct amount of sunlight, this color naturally transforms into a golden shade.
Fake sea moss has a lighter tone and is typically yellow or off-white. Because sea moss naturally comes in a variety of colors, if your sea moss all appears to be the exact same color it is most likely fake.
There is also a difference between the texture of real and fake sea moss. Naturally, sea moss will have salt clinging to its surface. Real sea moss absorbs the salt from the ocean that it is grown in and this is visible on its surface.
There will be noticeable differences between the salt that coats real sea moss and the salt that coats fake sea moss. If the sea moss is covered in a fine salt then it is real, however, if the salt looks like table salt or rock salt, it is more than likely fake.
The difference in salt will also become more apparent in the taste. Whilst you can taste the salt on real sea moss it isn’t overpowering. The taste of fake sea moss is much more synthetic.
Another indicator of fake moss can be identified through the lack of seaweed and sea dirt residue. Often, real sea moss will have pieces of seaweed mixed in with it as it is found in the same environment. It may also have bits of sea dirt or sand on it that it has come into contact with in the ocean.
Fake moss, however, will not have occasional strands of seaweed mixed in with it because there are no species of it present in pool tanks. It will neither have bits of sand on it.
The feel of fake sea moss also differs from that of real sea moss. The latter doesn’t contain moisture so it is drier, however fake sea moss will feel much more moist and slippery. It also lacks the chunkiness of real moss which will likely become more noticeable as you handle it.
Finally, you can also identify fake sea moss by the price at which it retails. Real sea moss tends to cost more than fake sea moss.