Floating plant growth issues

[Mattant1984]

Hi all,
So I've had some amazon frogbit and dwarf water lettuce in my tank for a couple of months. Up until recently it's been growing super healthy and lush green and multiplying very quickly. (I was thinning it out every 10 days).
It's now not looking as healthy with dying and browning leaves and growing a lot slower.

-It's a 34l fluval flex
-Lights running at 50% and for 6 hours a day
-TNC complete added 1.5ml daily

Now here's what I have recently changed over the last few weeks:
-Recapped the tank removing nearly all the stem plants, keeping ferns, anubias and crypts.
-upped the flow on the surface (could this be why??)

Everything else in the tank is the same as before.
I've added some pictures of the current state of the floaters.

Many thanks

 

[Maf 2500]

-upped the flow on the surface (could this be why??)

If the floating leaves are getting splashed and submerged by the flow, they won't like that... also six hours is a bit short for a photoperiod.

 

[Oldguy]

upped the flow on the surface (could this be why??)

I have a high flow rate and cannot grow floaters. So high flow rate and short photoperiod are your culprits.
However on the up side good submerged plant growth and no surface film.

 

[Mattant1984]

Thanks for your reply guys, I have now reduced the surface flow and will up the photoperiod to 8 hours tomorrow.
Fingers crossed that helps