Help; Gnats in the black water tank

[D in Davie]

I moved to a campground and got gnats in my black water tank as soon as I hooked up. I keep the valve closed and chemicals in the tank. I have used vinegar in the tank and have taken to spraying flying insect spray down the hole when I flush but to no avail. I have flushed the tank out several times but they return. How can I prevent these things and get rid of them?

[Perry White]

Make sure you have a water trap in your sewer drain hose. Did you dump the black tank when you hooked up? That's where they usually come from. I know you say the valve is closed but I've run into your problem down in Mississippi.

You might want to get somw Spectracide or malathon liguid bug killer from Lowes or Home Depot and close the black tank valve. dump the bug killer down the toilet and fill the black tank full and then dump.

Also cold be coming down the vent from top. Screen over vent maybe.

[MRBB]

Darin the tank. Take a flea bomb and open it up and stick it in the drain tube with the black valve open. Use a rag or plastic bag to cover the opening. Let everything sit for about 2 hrs and you should be good to go.

[D in Davie]

Thanks for the resonses. I will try all of the ideas tomorrow.

[powerboatr]

you may try adding some liquid bug killer to your flush hose then flush the blank tank and let the swirler spray bug killer and get em good