If you have to much light on a low tech tank the uptake demand for CO2 is higher than you could ever provide with excel...high light asks plants to grow faster, but without prober building blocks to do that they will suffer. Lower your light to 5-6 hours per day and less intensive (T5's are powerful), cut away damaged leaves as they won't recover and only give you more trouble in the form of to much organic waste in your tank. Swords like some fertz at their feet, maybe after a few week add some root taps if needed. Hope everything recovers fast, but in low tech it can take more time.
Thanks for the advice I'll drop the lighting period down to six as changing them out isn't an option at the minute and I'll see how I get on, already putting root tabs in under the swords, next time when I upgrade gonna try a dirted tank I think and cut my water with RO as its really hard here and is probably contributing to my plants decline
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