[Mikell]

Originally Posted by Nomad28743

Ode to Mikell
It was worth reading the last 6 pages for this one snip it: Misinformation is rampant on cannabis forums, (this quote was stolen from Abraham Lincoln) take what you read with a grain of salt, especially the wanker (So British) chicken pecking this post out right now. Fucking tablets. Which tablets are you referring to?

Tablets re: those bastard computer-smart phone offspring.

Glad you enjoyed that

[yankeetransplnt]

Not sure about age of this thread, but was doing research on different hydro addatives beneficial to roots and came across the fungus gnat comment....H202 will kill om contact including eggs.....works every time..YT

[Phaeton]

Fungus Gnats have been a problem off and on for years.
The Perlite layer on top as a barrier only works if the layer is kept dry.

No sweat, the media is rockwool croutons and a layer of Perlite an inch and a half deep is put on top. I hand water and scoop a small hole in the Perlite to the rockwool layer.
The water goes in the hole and a measured amount goes in until the water level is a half inch under the top of the Perlite. Wicking wets the last half inch. Perlite does not wick moisture and remains dry, the Perlite around the hole is brushed back in and the entire layer is now dry and impervious to Fungus Gnats.

This works. It takes a few minutes more each watering but no chemicals are used and the gnats are reduced over 90%.
It is cheap and used on every container in the garden.

Any soap solution that is sprayed directly on gnats or Spider Mites will kill them. Soap is a wetting agent and it flows the water into the breathing pores on the exoskeleton, suffocating them. Any soapy water will do this, extra pesticide is often added but is not necessary.

[Oregonian]

Originally Posted by whodi

What about adding a top layer of hydroton rocks on top of the coco, fingers? Seems like I read that helps control gnats.. I may try it myself.

I use netting. 5 gallon paint strainers can fit over many containers. I cut about an 8" slit and tie it off. Then roll the cut ends and use a clothes pin or metal clip. Currently I'm using two paint strainers around my 3 gallon air pot. You'll never see an gnat again. It's a one time purchase deal with the netting. No mess to breath or chemicals. To clean them just throw them in the wash.

[Phaeton]

Spiders breathe through skin pores. Ordinary unadulterated water beads up on their exoskeleton and does not interfere with respiration. Use of a wetting agent allows the water to flow into the pores and suffocate the stinking bug.
Soap is a wetting agent, alcohol is a wetting agent.
Some agents are used to flow poison into the bugs as well, some are thick and clog the pore forever, some evaporate and the bug wakes back up again.
Johnson's Baby Shampoo a teaspoon per gallon has worked through three infestations attacking the garden in the last 15 years. Neem oil and soap was used twice but is so much yuckier without being more effective.

Alaska's climate discourages bugs anyway and that may be helping me as well.

As for putting Hydrotron on top...I use Perlite an inch thick on top and keep it dry when watering. This stops 80% of the egg laying.

The half and half photo is from some side by sides pitting Perlite against Rockwool croutons, not relevant to bugs at all. The other photo shows the Perlite topping, I am sure the reflected light helps although it has not shown up in the harvests.
Bugs and roots both love Rockwool more than Perlite but it is keeping the media dry so the eggs won't take that makes the top layer effective.

EDIT: Seems I replied a year and a half ago at about the same spot. At least I used different pictures this time but I gotta quit skimming and read entire threads before responding.

[RedACD]

A lot of great info in this old thread. Going to try out some SM-90 on a spider mite outbreak I'm going through.