Is my hornswort melting?

[Kimm87]

A few days ago i did a 75% water change on my frog tank and added a small preset heater in there because the temp had droped from its normal 78 down to 74 for some reason. I just looked into the tank and the hornswort looks loke its covered in like green slime and its all over the tank. Is the temp change causing it to melt? The tank is currently at 81 which may actually be to high for the frogs but they seem fine.
The quality of these pictures are terrible sorry

 

[Byron]

The green slime is algae or possibly cyanobacteria, it is hard to tell from the photos. Light and nutrients cause these. If this plant were failing, it would more likely begin dropping its leaves, rapidly.

You don't mention the frog species, but 74F should not be a problem. I assume the 81F is due to hot weather? Not much you can do about that so it is best to wait it out.

 

[Kimm87]

It doesnt look like algae it looks like the leaves are dissolving ill try to get a better picture. I have a pair of adf and the rise in temp is from the preset heater i havnt used it in a long time it should be set to 78f but the temp kept rising after i added it so it could be defective.

 

[Kimm87]

I couldn't get a better picture of the stuff on the plant but this is what it looked like when i removed the plant from the tank. It took me 20 minutes of scooping it iut with a net to clean 75% of it up

 

[Byron]

It doesnt look like algae it looks like the leaves are dissolving ill try to get a better picture. I have a pair of adf and the rise in temp is from the preset heater i havnt used it in a long time it should be set to 78f but the temp kept rising after i added it so it could be defective.

Heaters frequently do not maintain the exact set temperature, but that does not mean they are faulty. I have several heaters, all good quality brands, and rarely does the setting at say 25 C result in 25 C temperature of the water. Some heaters heat above the set temperature, so turn the setting down a very little at a time until the heater is not on. This should be at the temperature of the water (you have to start with the desired temperature in the tank). My Eheim Jager is set at 18 C and it maintains the tank water at a constant 24 C. I have had it for three or four years now.

Those photos do show more of a plant falling apart. Hornwort is notorious for this, and a sudden temperature change especially upward can do this.