What lighting? Most likely, co2 is way low. One bubble per minute? I probably have mine to two per second on my 40. That would probably be too much for you with a smaller tank and especially if your light isn't as strong, but ramping it up slowly is a good idea. That's a plant that loves, loves, lov...

About how much of this stuff are you adding? Sometimes the problem is too much of something and not a deficiency.

Improper ratio of N to P (too much P). Do a search for Redfield ratio. As Kris mentioned, clean everything well. Clean filter monthly. Consider adding another filter. Clean that one monthly too. Get a surface skimmer if you don't have one. Aerate at night. Flourish Nitrogen is a superior nitrogen so...

Yes

I'm told that it's Euphorbia lathyris.
https://gobotany.newenglandwild.org/spe ... /lathyris/

Yes, thanks.

I am interested in using the PAR meter. If nobody is using it, can you bring it in?

I have some Hottonia to share. It's actually Kris' but he won't mind if you take some.

Can you repost this in a public area? I want to call in some help but will need a link that can be accessed by someone who isn't a member.

Looks like something from Euphorbiaceae. I will poke around a bit. Not so sure it's a native plant.