So, I added a 23 Watt light to my fuge and within a week there was an explosion of this weird hairball looking orangish algae. There is also a massive buildup pf detritus down there. Also, My Chaeto is growing like crazy (good thing). And lastly, there is an explosion of white flatworms. What should I do.

Also, there seems to be leaves growing out of my Chaeto...I don't think Chaeto grows leaves....maybe my LFS got something else mixed up in the Chaeto I bought.

The leaves weren't there last week and they are about 2-3 inches long right now.

If the leaves are growing out of the chaeto, it's probably a sp. of caulurpa mixed in. the other algae stuff, just give it time. your tank is still really new. algae blooms are totally common. are you sure the orange isn't a sponge of some type?

Dhaut,
This is totally algae. It's in the sump. It's orange (or maybe brownish) balls of hair everywhere. And detritus like crazy. Are you saying I should leave the detritus too?

Better your sump than main tank yes? Whenever you make a change to the balance like that (Stronger or more light etc) it takes a day or two for nature to react. Give it some time, the macro algae will out compete the micro (brown/hair/sludge) algae given enough time. Just be sure to prune the macro algae back once a week. By doing this you remove the nutrients (the phos/nitrate/nitrite) that the macro algae absorbed and get it out of the system. You also encourage the macro to stay in growth mode which causes it to keep absorbing the stuff before the micro algae can use it.

nah, siphon out the detritus. you can try to get some of the microalgae too.

but it's a battle that will have to be won with time. your tank is new - give it a chance to mature a bit while doing things to help like water changes, algae pruning, siphoning detritus, etc.