hornwort not thriving

[mousey]

Sorry but I can't get the search button to work or I would look this up.
Anyway my hornwort plants were bought 5 years ago and have done fine up until this year. In 3 tanks it is dying. I wonder if the other plants are outcompeting it now. I have vals, anubias and java ferns in 2 tanks. the 3rd tank has a few sagitarius( looks like mini vals) as well as a huge amount of hair algae. I only light for 4-5 hours a day and always have on all tanks. The only thing different is the days are longer now so there is more light in the room. This has not been an issue the previous 4 years.
I am trying a bit outside in the sunlight but it does not seem to like the experience so far. It has dropped all its leaves. Any ideas?
We havce hard water, ph 8, I fert monthly and do water changes every 2 weeks.
Fish are mostly livebearers and tetras.

[emc7]

I blame the hair algae. It clings to the hornwort. Throw out all the hornwort that looks sickly. A smaller amount will get more light and nutrients. Hopefully it will bounce back.

[Thomas]

It is possible the algae covers the leaves & reduce the light. Then kill the hornwort

[JustOneMore20]

How many watts of light are over each tank and how many gallons are they? Algae could be the problem though, especially if you are getting alot of sunlight on the tanks. I'd start by trying to leave the lights on over the tanks for 8 hours. 4-5 doesn't seem enough to me.