Hello,

I think this is different for different types of plants.

I can say with some confidence that Jack Heller’s cultivar of Hornwort (which doesn’t drop its leaves and make a mess in the tank) can tolerate up to SG 1.004 (~5g/L).

I am told that some cultivars of Java Moss can tolerate 1.005 SG (6 g/L).

I have been keeping Pseudomugil cyanodorsali at 5g/L with hornwort and java moss with no issues. Sadly, even teh duckweek seems to survive.

I keep anacharis and java moss in my tanks set up for pupfish.  I’m not exactly sure of the salinity but I do add approx. 1/2 tsp per gallon and calcium carbonate and soda ash so it’s very hard and the pH is around 8.2.  Doesn’t seem to bother these plants, the snails are healthy and the fish love it.  Hope this helps.

Russel,

Helps immensely thank You!

I asked in another post about my lack of success with Ceratopteris thalictroides Water Sprite and people thought my use of salt killed it. I have Vesicularia dubyana Java Moss and Microsorium pteropus Java Fern that is thriving with my dose of added salt. 4 teaspoons per 10 gallons. Something unusual about my Java Fern is that it is not rooted or attached to anything. It grows free floating.

Duckweed is salt tolerant. It can survive brackish conditions.

Duckweed is salt tolerant. It can survive brackish conditions.

I believe duckweed will survive a thermonuclear explosion

Duckweed is salt tolerant. It can survive brackish conditions.

I believe duckweed will survive a thermonuclear explosion

Yes, duckweed, cockroaches and scorpions. And entire little ecosystem of horror will survive WWIII.

Ruppia sp. (widgeonweed) can survive and thrive in high salt conditions, up to full strength seawater.

I keep a species of blue-eyes (P. ivantosoffi) for years which does well at 1/2 seawater and I found that java moss would last for months, but would eventually die. Even then, it would just slowly go yellow and still provide the cover functions without any significant pollution.

But I have found that Susswasertang (Lomariopsis) stays green indefinitely, though it doesn’t seem to grow. I prefer the tang in general over moss for a number of reasons even in my usual, soft water tanks.

I’m interested in trying Susswasertang, where did you find this plant?

I got mine through my local aquarium club, the Minnesota Aquarium Society.

It should ship easily and I would be happy to send you some, but it’s the wrong time of year for me to do that. Hit me up in the Spring if you haven’t found some.

As a follow up on this, I purchased some Susswasertang on Aquabid and put it in my brackish tanks and it did not work out.  It took a bit of time but it all dissolved.  I think I’ll try some true macro algae in the tanks and see if that works.