Detritus Worms

I'm posting in here as an article I've just read says they are found in tanks with poor filtration, amongst other reasons. ( I don't know how to post a link, it's from 'fish as pets aquatic news')
I'm currently cycling my 55l tank and have found a load of tiny thread like worms on the glass. Googling has lead me to the conclusion they are detritus worms (harmless) rather than planaria (not harmless).
But the population explosion is a sign of bad conditions in the tank apparently.
There are no fish, so no over feeding is going on.
There is quite a lot of the bottom layer of substrate hanging about on top of the sand since I planted some plants a few days back. I tried to remove it yesterday by vacuuming, and that stirred it up into the water column, made it very murky for a while.
Do you think that is the cause?
The other possibility is poor oxygenation, do I need to get an air stone?
The minute I turn the pump rate up, the tank overflows, so I'm keeping it turned down atm.
Any advice would be most welcome.

I haven't come across these critters before, but say they hang about in the tank until after the cycling is complete, would any fish subsequently added not eat them?

The tiny thin worms we see crawling on the glass or wriggling in the water are quite harmless. The cause is usually decaying organic matter in the tank. In your case it is obviously not uneaten fish food, but you have some plants in the tank, and if there are any bits of dead that would feed them.

Didn't you use garden soil on the bottom of the tank? I've never used it, but perhaps someone who has could comment if any decaying organic material would be present in the garden soil, and if that would feed the worms.