Can make a decision on new lighting

[Piper]

Hi all. Due to funding issues my temporary tank 40g 120x40x30cm is now going to be with me for a while. It has just a single 30w t8 tube and I don't know if I can get away with adding a twin 39w unit or if I need to get a 4x39 t5 unit and remove the old t8. I want to grow UG, Blyxa and hair grass. I'll be doing ei with pressurized co2. Any advise ?

 

[Luketendo]

Twin T5 should be fine. Four may be a bit overboard unless you can keep ferts and co2 right in balanace.