4 T5 tubes, even without reflectors, is well and truly in the very very high light region of light intensity, you will be able to both grow and vaporise any type of aquatic plant with this level of light.
Your plants not doing well is nothing to do with light & its levels, if you replace with suitably expensive LED's that even come near T5 HO light levels you will still suffer poor plants is nothing to do with light.
You have actually told us 100% why your plants are so poor...hint below...(as well as light levels being way way way way way too high).
What fertilising dosing and regime are you using as well ?
What is your filter and its turn over rate ?
My suggestions..
1. Change to bottled CO2 injection solution to get proper/correct levels of CO2. 99.999% of plant problems seen here are poor CO2 implementation. I very much doubt you are the 0.001% that is not poor CO2.
2. Run with only 2 T5 tubes (or less by blocking the tubes with foil rings).
3. Add fertilisers.
4. Report back to use what your way forward is going to be, please.