Worms id

[Kishore]

I found a few worms wiggling in my tank's sand bottom. They are reddish, very thin and have made tunnel-like paths for them. I am totally grossed by them. They definitely weren't there a week ago.
I am attaching a picture and a video of them. Please help me id them and kill them if they are harmful.

The only major change i did to the tank recently was adding a couple of led lights. This tank was previously without any lights. Now, the addition of lights seems to have created brownish algae in the tank (you can see it in the pictures). What have I done wrong here? Any tips?

https://drive.google.com/open?id=1Fdw3pqpM7b1g_4dG9T0e0gD_qARwpf7V
https://drive.google.com/open?id=1cny1GXZ1Q2l6rbYKmnDjPaBsDRjRaQJO

 

[Autumnsky]

These seem like detritus worms.

Ways to help rid your tank of them would be to decrease feeding quantities, and clean more often.

*Vac the substrate and remove build up waste which they feed on.
*Increase the quality of the water by doing more frequent water changes.
*Clean your filter pads rinsing in the cleaner top part of the pwc (partial water change) water / not the mucky stuff vac'ed out of the bottom. Or rinsed dechlorinated fresh water.

As for the light, how long are you keeping it on?

What size tank do you have and what type of light did you add. Generally the algae would indicate too much light. And you can reduce the lights on period each day.

If you do not have live plants, you can also leave the light off for a while like days or week and then slowly increase the lights on time.

The brownish gunk might be diatoms here someone describes them.
https://microcosmos.foldscope.com/?p=15327

 

[Kishore]

These seem like detritus worms.

But I thought detritus worms are white?. These are reddish.
Also, are they harmful? Should I remove them or leave them be?

I have a 40 gal tank and 10W leds running for about 11-12 hours a day. Could the sudden change from no lights to this have caused the growth of diatoms? I am thinking of adding some floating plants though. Right now, my primary concern is the worms.