Hornwort in three tanks - questions

I have three tanks going, with hornwort in each. I got the hornwort at the same time from the same source.
55 g with 2 adult goldfish & about 20 fry (2 months old) - hornwort in this tank is thriving and bright green. Comparing this to other tanks.
18 g with about 8 goldfish fry that are 3 weeks old - hornwort has a lot of stuff growing on it. This tank previously had 4 amano shrimp and has an under gravel filter and layers of gravel, polyester batting and fabric with sand on top. (I did it almost two years ago when I knew nothing and followed some directions I found online.) It had a lot of stuff growing - maybe fungus (jelly like balls) and hairy algae. I didn’t know what to do to clean it, so I had planned to take it apart, scrub it down, get rid of the under gravel filter (It already has an Aquaclear 50 HOB in addition to the gravel filter), and replace the sand. Then after I moved the shrimp to their new tank, I saw some tiny fry swimming (I assume there must have been goldfish eggs on the hornwort.) So I am trying to clean around the tiny fry. They spend time apparently eating something from the hornwort, but it is all covered with the hairy algae that was everywhere in the tank. Should I try to remove the algae from the hornwort or will it be food for the fry?
20 g with four shrimp - hornwort isn’t dying, but it’s not thriving. End growth is brown and it’s not lush like the 55 g tank.
I’ll add photos. I don’t know how to label them or put them in order, but they match the description.
Thank you!
P.S. Looking for loving homes for all the surprise fry!

 

I wish I could be more help, but all I've got is that hornwort is just finicky. I have it in two aquariums and a couple of tubs outside. When I add it to a new tank it generally does one of two things: thrive, or drop every needle in the first two days and never recover.

 

Hornwort gets all of its nutrients from the water, and it looks like the adult goldfish are producing plenty of bio material for it to feed on (which is why the plant looks so healthy). Once established, it will out compete pesky algae which you are noticing in the fry tank. Shrimp and fry need all of that tiny goodness so don't make the environment too 'clean'.

 

As stated hornwort can grow great in one tank and die in the one next to it. In the first pick it looks like hair algae growing on it. I’d guess the nitrates or phosphate are high in this tank.
Second pic the hornwort looks great! Is it planted or floating? What type of lighting? 3rd and forth pics are from the same tank and I’d say not enough lighting. The branches are getting spread apart and probably closer at the top. I would try floating some in that tank and see what happens.

 

It’s all floating. I bought lights that said they were for plants. I’ll check the parameters. The ones that aren’t growing well have a hygger Advanced Full Spectrum LED. The one that’s growing well has a NICREW ClassicLED Plus Planted Aquarium Light, Full Spectrum LED.