I need a liquid remedy I can use to battle fungus gnats in house plant

Repot the succulents in fresh soil and spray them down with neem oil. Fungus gnats lay eggs in the soil if left untreated the problem will never go away

First things first will be to repot all the infected plants. Make sure you clean the pot really well. After that, there are chemicals you can use on the plants, I would also put a gnat trap by the worst off plants to capture all you can. Probably wouldn't hurt to rinse off the plants either. I would do all this outdoors to help get rid of the buggers outside rather than leaving the offenders in the house to get on the plants again.

Here is a remedy to rid your house of these pests... http://www.finegardening.com/get-rid-fungus-gnats

maybe this can help

http://www.wikihow.com/Get-Rid-of-Gnats

I have had no experience with fungus gnats BUT have had other critters from time to time. Do fungus gnats live in the soil? If so, the obvious solution is to change the soil after washing the infected pots VERY well ... as Nancy Turner is suggesting. I would also try and move the infected plants away from other healthy plants before you have a larger problem. Air plants can be easily rinsed off; in fact, they love it. Succulents are usually tough plants as long as they aren't overwatered and are allowed to DRY out in between waterings. I assume you do that with yours. If not, please do so as constantly moist soil is a breeding ground for fungus, mold and bugs!

Gnats do not like the smell of vinegar. Put vinegar and a drop or two of dishwashing soap in small glasses or bowls whatever you have and place them amongst your plants. I had the same problem with gnats and they all disappeared overnight.

You might try spraying them with Simple Green. It is not hard on plants and kills small pests as well as fungus, etc. It is a disinfectant that is not bad for the environment. I use it to kill small moths and fruit flies when my house gets them. It is also a disinfectant so I use it to do all my cleaning in my home. You can find it in the cleansing department at Menards in spray bottle or concentrate. (I buy concentrate and it lasts a year). If I were you I would purchase one of each so you have a Simple Green spray bottle for the concentrate. Also you can find it at the auto/boat section of Walmart. If you get fruit flies you can spray your sink drains and it will kill them too. They live in drains if you keep fruit refrigerated.

They actually have a short lifespan but are hatching in the soil and replenishing themselves. Let the soil dry out completely and this will destroy the eggs that are hatching. After several days of dry soil you can then water again.

I had the same problem. I took bright yellow paper put it on a stick with anything sticky on the exposed sides of the paper, depending on the plant size use multiple traps. Enclose the entire plant in plastic ( don't use Black) and leave it alone. I left mine for over 2 weeks. Don't open or be tempted to water. Once you catch the female and any all the larvae have hatched your problem should be gone. Good luck.