No, the CO2 is not too high for the plants...........however it may be too high for the fish!

That is our upper limit for adding CO2: fish health and well being.
This is the most critical of all parameters to focus on.

For all the banter and debate on the web over EI, over ADA and various "methods", I think I am one of the very few people that give CO2 proper and due attention.
I might be very critical about it, but with good reason, it's the plants/fish health that are very much linked to it as well as algae related issues.

I would suggest you try this CO2 mist method directed at the specific species of interest here, the Tonia and the Rotala.
Have the current push the CO2 mist directly into the groups that are hardest tom grow.

I have been successful growing this species of Tonia and any other plants in inert substrates.

As you are more concerned about Dutch planting styles, I agree ADA might not be for you. But one concern many have is using a more easy to grow suitable species effectively rather than harder "species of the month or year".

Check out NBAT's web site going back several years, each of the top 5-10 winners have very good strong themes and make wonderful models.

Pay attention to the foreground care and look.
It takes about 8-12 weeks to get a tank into that condition.
2x a week water changes, thoughtful consideration about pruning and knowing how fast each plant species will grow, so timing is important.

That way you have a nice very thick group of plants for each and every group!
Clean tanks win contest also. Water changes really help and staying on top of everything does as well.

Regards,

Tom Barr