Just treated some ick without medicine recently so memories still fresh.
One tablespoon to 20 litres I think not enough to treat Ick. One tablespoon is about 20grams, so that is about 0.1% salt.
After hiding beneath the skin the ick parasites will form a clust on the skin forming a white spot, then the clust will drop and thousands of parasites will be born and they will go to the gravel, and after a while thousands will be free swimming and finding a host to infect. The salt part is to dehydrate the free swimming parasites and kill them.
One tablespoon to 20 litres I think not enough to treat Ick. One tablespoon is about 20grams, so that is about 0.1% salt.
Usually people add salt to 0.1 percent which is about 1 gram per litre, as preventive measure. When fish get white spot they increase to 0.3 percent 3 gram per litre. But that is not enough, best is to take out the infected fishes, as they holds the most parasites, and give the fishes a salt bath.
For a salt bath, use another small tank, salt is added to 1 percent to 3 percent, that is 10 to 30 grams per litre, for 10 to 30 minutes, depending on the condition and size of your fish. And most importantly add an airstone, make sure water is heavily aerated.
Maybe go for 2 percent salt for 20 minutes. Sometimes I go higher and longer but must be very careful to watch the fish all the while during the bath because if you notice them flip over or appears like gasping for air at surface and stays at bottom looking like dying, it means they cannot take it anymore.
When salt bathing always fill the water to half tank level only and standby another pail of dechlorinsed water, in case you need to dilute the water when your fish gets knock out by the salt treatment.
Regards
Live and let live, stop using life feeds.
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