Keep T8's or switch to T5'S?

in the live planted tank hobby there's a lot of disagreement about lighting, substrate and fertilizer usage.

so as long as you understand where the advice is coming from you'll have a better time sorting it all out.

most of the people here, or posts on other forums like youtube are people new to the hobby or for whom your tank would look amazing. And many youtube videos are of tanks that are days or weeks old, not established and can prove nothing.

your tank is a perfect example of what a tank with insufficient light intensity looks like. Small spindly plants and not a lot of new growth, certainly not what you'd call "lush"

now, that being said, you also don't want to spend thousands of dollars and may not get a tank that looks like this......

http://37.media.tumblr.com/tumblr_m800s9GgIP1rra1j...

but you can improve your tank greatly by doubling the quantity of lights.

whether you DIY or buy a new light system is up to you.

T5 lights have more watts per tube so are a better choice than the t8 bulbs (note: you cannot put a t5 bulb in a t8 fixture or visa versa; they'll light maybe, but not provide the intensity you are looking for)

so, either build a 4 light T5 fixture, or add a 2 bulb T5 fixture to your current set up.

additional notes: bulbs lose intensity by about half in 6 months so set up a schedule for replacing one bulb every 3-6 months so the light remains about the same.

or, buy a new led light and add it to your current lights. (note: manufacturers lie about the size tank a light will handle. Marineland for example overestimates their lights and you would need two fixtures rated for your tank to be sufficient)

LED lights can be found that are very intense and use much less electricity and don't lose intensity the way fluorescents do.

High end lighting suppliers will give you a better idea of the watts you need, and you can use that info to estimate how much of a cheaper light you might need. Call one of them and get some of your questions answered.

the addition of co2 is what makes truly spectacular live planted tanks, but is only useful if you also have the light intensity required for the plants to use the co2. It's pointless to increase fertilizing if you don't have the light and co2 necessary and you don't increase the co2 without having the light and fertilizing required. etc. etc.

good luck, and I sympathize with your confusion. These things are argued about intensely on the live planted tank forums online.

but for now, bump up your lighting and see what happens.

I think t8's are better than t5's. Because t8 led tubes come with isolated drivers and have one ended power supplies for safety. As you want to plant them in a tank, it's better to read the manual of both the lights.