3 levels of the same plant?

[AdamsB]

Ok so I'm far from a plant expert, but i know a little. Which could be more dangerous than knowing nothing

I bought some "hornwort" from petsmart about 4 weeks ago. It had 3 stems tied up, all looking identical. Now all 3 stems are turning out completely different. They started off floating and its how i kept them since. But one is fully green and floating nicely, one is turning a yellowish colour and kinda in between floating and sinking. The last one is green, but not vibrant like the first and sinks to the bottom. I don't use ferts, i have a stock 15w t8 light (2 lights, split in the middle) and i do 20% water changes twice a week.



So my questions.

1. What makes a "floating plant" not float? Theres no build up of algae or anything on it.

2. I know when dosing CO2 its best not to have surface agitation, could my HOB filter be moving the surface too muchcausing too much gas exchange and letting out whatever CO2 is in the tank?

3. I know my lights are pretty poor but how could one strand thrive while the others fail to?

Any input much appreciated as always

[effox]

This is just pure speculation, but it almost seems as if the hornwort is moving back and forth with the surface agitation, blocking the light to the other two plants.

I've never had a problem with hornwort, and honestly didn't even realize it was a floating plant until now as it had roots and was extremely happy to be planted. Perhaps trying to add weights to it to keep it in one place, thereby preventing it from blocking light might be a way to troubleshoot?

These definitely DO NOT require co2, and should be growing excessively at this point.

Cheers,
Chris