[dwalstad]

Patience is not my strongest attribute, but I guess I'll take this opportunity to work on it .
I did add a few more rooted plants into the tank and I'll up the photoperiod to a total of 10 hours.

It sounds like you are doing all the right things.
Note: Your previous photoperiod (4 hours on, 3 hours off, and 4 hours on) is 11 hours--not 8 hours. The photoperiod is the total daylength not how how long the light are on. If you increase the Siesta to 4 hr instead of 3 hr, you will have a 12 hr photoperiod. That is good for plants. I recommend a photoperiod of at least 12 hr for a low-tech tank.

 

[Bored_Conscious]

Update: It's been around two-weeks at this point.
I am seeing some new growth on my frogbit. It's producing several new leaves at this point. In regards to the other plants, not much has changed except maybe the hornwort has grown a bit.
Can't entirely tell if it's just the hornwort straightening out or it actually growing a bit. I did accidently uproot my val during a water change and it does appear to be growing new roots, which is good. Hopefully within the next week or so, it will finally reach down into the substrate and then take off.

Still doing water changes every other day for the most part.

Would a stronger LED be beneficial for my tank? At the moment, I have a small 12W LED light that's rated for ~49-50µMol/M²S PAR @ 12inches (This was an extra light fixture I had for a terrarium I have. Are PAR ratings different on land vs. water?). The light doesn't cover the entire tank. The light is strongest at the back left corner and less intense elsewhere.

 

[dwalstad]

Unless you see water cloudiness, I would stop doing water changes and reduce the water level.
Your plants--especially hornwort-- should be growing by now.
I wonder what the GH and KH in your tank? Plants--especially hornwort, a hardwater plants--needs water hardness. And we don't know if you have house water softening system that is pumping Na into your tank. So many factors...
Until you get that Hornwort growing, I suspect that something is amiss. I think your lighting is probably okay. I have Hornwort growing fine (too much!) at less PAR than yours.

 

[Bored_Conscious]

Unless you see water cloudiness, I would stop doing water changes and reduce the water level.
Your plants--especially hornwort-- should be growing by now.
I wonder what the GH and KH in your tank? Plants--especially hornwort, a hardwater plants--needs water hardness. And we don't know if you have house water softening system that is pumping Na into your tank. So many factors...
Until you get that Hornwort growing, I suspect that something is amiss. I think your lighting is probably okay. I have Hornwort growing fine (too much!) at less PAR than yours.

I probably was a bit more dramatic than I should have. The hornwort have grown, just not as substantially as I would have predicted considering people say they grow like crazy. The frogbit have propagated quite a bit since the initial two I had.

Also, while doing a water change yesterday, I noticed that the vals have actually sent out runners!

My GH and KH are extremely high in my area so I don't think that is an issue if it were.

My water does get slightly cloudy though the day after a water change. I'm not entirely sure why it isn't crystal clear (I don't mind tannins, but you can tell something is foggying up the water).
Most of the dwarf hair grass, ludwigia broadleaf, and another plant I don't remember the name of are partially covered in a brown algae sort of thing. Anything I should do about that?

 

[Gooblikon]

I probably was a bit more dramatic than I should have. The hornwort have grown, just not as substantially as I would have predicted considering people say they grow like crazy. The frogbit have propagated quite a bit since the initial two I had.

Also, while doing a water change yesterday, I noticed that the vals have actually sent out runners!

My GH and KH are extremely high in my area so I don't think that is an issue if it were.

My water does get slightly cloudy though the day after a water change. I'm not entirely sure why it isn't crystal clear (I don't mind tannins, but you can tell something is foggying up the water).
Most of the dwarf hair grass, ludwigia broadleaf, and another plant I don't remember the name of are partially covered in a brown algae sort of thing. Anything I should do about that?

Invertebrates will help clear up algae and if the parameters are returning correct an algae eating fish will do the job nicely. As for the light, if there aren't any photosensitive fish in there nothing wrong with grabbing a stronger light, I would look in the 20-30 range if possible (LED).

 

[Bored_Conscious]

Update: Got rid of a few plants that didn't make it, but the remaining (hornwort, frogbit, Vals, Ludwigia) seem to be doing well and growing. I've noticed a weird trend however. Whenever I test ammonia levels after a period of no-light (So, right before my light turns on in the morning or after the siesta period) ammonia levels seem to rise a bit. However, when I measure ammonia levels near the end of my light cycle (right before the siesta period or right before the light turns off for the night) ammonia levels seem to have decreased.

Ammonia levels are around 1 to 2 ppm after a period of darkness and near the end of the light cycle, the ammonia levels are around 0 to .5 ppm.

Why is this? I was under the impression plants will make use of ammonia regardless of day or night? Was I misinformed?

 

[dwalstad]

Update: Got rid of a few plants that didn't make it, but the remaining (hornwort, frogbit, Vals, Ludwigia) seem to be doing well and growing. I've noticed a weird trend however. Whenever I test ammonia levels after a period of no-light (So, right before my light turns on in the morning or after the siesta period) ammonia levels seem to rise a bit. However, when I measure ammonia levels near the end of my light cycle (right before the siesta period or right before the light turns off for the night) ammonia levels seem to have decreased.

Ammonia levels are around 1 to 2 ppm after a period of darkness and near the end of the light cycle, the ammonia levels are around 0 to .5 ppm.

Why is this? I was under the impression plants will make use of ammonia regardless of day or night? Was I misinformed?

No, you were not misinformed. I do not think that ammonia uptake by plants is relevant here.
If your tank was truly established, you should have NO ammonia whatsoever day or night. Plants would be taking it all up. In your tank, oxygen generated by day-time photosynthesis may be stimulating nitrifying bacteria and some ammonia removal. Not sure, but your observation is interesting. (To confirm, you could test for a diel cycle in nitrates or nitrite.)
Based on your first picture, I don't see a large plant biomass. Tank is 3 wks old. Soil decomposition is still pumping out ammonia. Driftwood may be releasing organics. Plants have not grown enough to handle the load.
Patience and/or more plants?