Fungus gnats living in rdwc res?

Sick Plants & Problems
#1

They are tiny almost look like fruit flies. I’ve never had or heard of fungus gnats in hydro.

I’ve been trying to reduce their numbers with frequent res changes and vacuuming them up, but they keep multiplying.

Was thinking h2o2 might kill them but I’m not sure if they are living in the water or on my netpots.

Sucks they are moving to my veg room.

Everytime I lift up a tote lid some fly out

I’ve been doing a lot of in and out of my basement from outside so I think that’s how they got introduced.

So right now my game plan is to put up yellow sticky traps and put some h2o2 in the res. The ones that escape end up dying so there’s nothing for them to eat outside of the res.

Anyone have any other suggestions?

#2

Also cover the netpots with dry perlite, and if possible on top of it sand. This will help. Be sure that there is no entrance for them at the reservoir/netpots/buckets.
(never saw it in hydro)

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#3

My control bucket is open and I have a couple sites I’m not using that have the cutouts open. I will close them off the best I can, but the control will be hard since I have a pump in it that pumps up to the chiller

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#4

My grandmother used mint planted around the garden to detour pest… It couldn’t hurt to place a few cotton balls with a little mint extract around your grow.

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#5

Adding small amounts of Hydrogen Peroxide into the mix will kill off some of the larvae.

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#6

Yeah, the control unit open is not great in this case, and the open sites just make everything even worse.

Hopefully you will get rid of these pests soon, the H2O2 will help with the larva. Perhaps a top dress on the pots themselves before you cover them somehow should also help to control them.

My main concern are the adults layong eggs (again) entering at the undersides of the pots.

Ohmy

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#7

Have you checked your roots?

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#8

Lots of good replies here OP, H2O2 is going to be your best friend for fighting the issue.

Remember that gnats aren’t a problem, they are a sign of a problem. Unhealthy roots will be a breeding ground for fungus such as Pythium/root rot and this is what the gnat larvae eat.

You need to clean your roots with H2O2. For a bad infestation you’ll want to use about 75ml of 3% peroxide per gallon of water in your res (you can go much higher without causing issues fyi). This will also serve a double purpose of killing off any larvae and eggs living in your roots.

Topdress your netpots with perlite or gnatnix to make it difficult for adults to get back into the res to lay eggs.

Fly traps and sticky traps placed strategically will help control the adults.

This should fix your problem 100%.

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#9

I’m gonna grab the 35% horticultural grade at the hydro store.

I used to use it when I ran sterile.

My total system is 90gal so the 3% wouldn’t cut it at 75ml/gal I’d be using 2 gallons of it.

Roots look fine. I’m not using a chiller cause it was either a chiller or an AC or popping breakers. I figured the AC cools the room which in turn cools the res. So the AC took priority.

Hate growing in the summer.

I will for sure top dress. I should have addressed this issue a few weeks ago when I first noticed.

I only have two weeks left. Wondering if I should just finish out the grow and clean once I chop

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#10

Either way the h2o2 will be something you’ll want to have on hand.

With two weeks out and no visible signs of damage to the roots or plant, I don’t think you have much to worry about. But I’ve seen gnats explode in numbers really quickly and they’re annoying when they’re buzzing around all over your grow (and rest of your house lol)

I use the 30% H2O2 at 5ml/gal. I’m currently using calcium hypochlorite (pool shock) in place of the peroxide as it’s cheaper and effective.

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#11

I’ve been keeping them at Bay with weekly res changes and sucking up all the adults I can see with a shop vac.

I saw these brown wiggly lines on the bottom of the totes. Not sure if that’s their shit or larvae. Never seen it before so I assume it’s related to the gnats.

I’m just worried about the new seeds I started since the roots are less abundant. They were also pricey rare dankness dark ghost train. Was like $99USD a 6 pack of fem.

I have them in coco since the taproots got all curly and I couldn’t straighten them to fit inside neoprene collars and into my aerocloner which is pretty sealed tight.

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#12

Probably larvae, but if they’re at the bottom they’re likely dead.

As for your new seedlings keep them happy and healthy with healthy roots and they should be fine.

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#13

Put one mosquito dunk in your res. Kills fungus gnat larvae too.

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#14

I’ve heard nothing but great results from the dunks/bti and afaik is safe for organic growers.

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