Advise on Lighting for 2ft tank

[annubis]

Hi,

I am trying my hand on doing a low tech tank. I have some questions about the type of light/wattage that would fit my needs. Appreciate any help I can get.

Tank - 60 x 30 x 50 cm (water volume - 90 litres)

Substrate - Lapis sand (plan to add wondergro+ tabs)

Flora - petite nana, spiky moss, taiwan moss, blyxa japonica, narrow leaf fern, some left over hornwort

Fauna - 14 Cherry Barbs, 2 SAE, 3 refugees from previous tank (2 platies & 1 molly), 1 horned snail (not sure exact name or if it is from the nirite family; got from LFS)

Fan (12pm - 12am)

Light (currently) - FL 15 Watt x 2 (12pm - 12am)

Dosing Excel 2ml everyday

Dosing fert once a week as per instruction when I top up my water. Haven't done any water changes.

I have the tank up for about 3 weeks - a month now. I noticed the moss are doing well. Some of my petite nanas has some yellow leaves (do I need to start dosing iron?). Hornwort used to be bushy n big, now left in smaller stems but growing. Japonica which I have for 4 days now, are starting to die out. This is probably because I haven't had time to planted them in the substrate w fert. Just added a Taiwan moss yesterday. Planning to start planting the Japonica's tonight.

I would like to know if my 2 tubes of 15 watt is enough for what I am doing or should I change it to a 36 or 55 watt PL light?

[Xianghao]

I think 55W for low tech is on the high side you will probably get an algae problem. Perhaps 20 to 30+W maybe a better bet.

[annubis]

Thanks man for your reply. Sorry Moderator, I posted in the wrong section...