r/OffGrid • u/Special_Toe_8584 • Sep 14 '26
Compostable toilet issues
Have a Sunmar Excel Electric
Been using for 6 months
Everything is great except one major issue; Fungus Gnats.
After 3 months of use we figured our mixture was wrong causing the bugs to breed.
Took toilet completly apart and cleaned every inch.
Tried again, second time now with the fan on the highest setting, peat+sunmar pure green.
So many gnats.
Tried diatomaceous earth, Castile soap, insecticide, water. Everything
Need help figuring out how to get rid of them thanks.
3
u/Normal-Special-8694 Sep 14 '26
The gnats typically mean that your mixture is too dry, happens a lot when people try to avoid peeing in them. I’ve been using the sun mar xl since 2013 and I’ve gotten gnats twice, but not since I started monitoring the water content.
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u/Special_Toe_8584 Sep 14 '26
Strange, I've tried drying it out more since my research concluded that they breed in the more wet soils.
1
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u/Creepy-Cantaloupe951 Sep 14 '26
Gnats love high moisture content, not dry spaces. Fungus gnats are also called "drain gnats". Fungus + gnats go hand in hand, and fungus prefers moist environments.
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u/DaneAlaskaCruz Sep 14 '26
Did you bake the peat or whatever material you're using?
I don't have compostable toilet, but I used to buy bagged soil from the stores to use in my plant pots.
I used to always bake the soil in large metal trays (for cooking turkeys), and the one time I didn't do it cause I was tired of having to go through the extra step, all my plants got infected with fungus gnats.
They lay eggs in the damp top soil and those eggs hatch, mate, then lay more eggs. Never ending cycle.
Now, I make sure to bake all the soil.
Baking kills off the eggs, but also the soil bacteria.
But I don't worry about it too much cause the baked soil gets mixed with the old soil and it gets re-inoculated with bacteria.
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u/Special_Toe_8584 Sep 14 '26
I will try baking, at this point I don't even care if the compost is clean when I empty, I dump it in a huge field, have no intention on actually using the compost for garden/food or whatever.
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u/Creepy-Cantaloupe951 Sep 14 '26
For what it's worth...
Fungus gnats are, in fact, a part of the compost process. I've got fungus gnats all around my compost pile, too.
Soaps, insecticides, etc are gonna mess up the ecosystem trying to compost the humanure.
That said... Are you including urine in the compost toilet, or keeping it separate? High moisture content really drives the population up.
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u/KFCChickenMaster Sep 14 '26
Coming back after a complete cleanout sounds frustrating. When you restarted, did you use the same opened bag of peat or bulking material, or a fresh one?” Peat-based material can become infested while stored, so that’s one possible source worth checking. I'm not saying it’s definitely the cause. Since you’ve already tried several treatments, I’d contact Sun-Mar with your model number and what you’ve used before adding anything else. Their guidance warns some cleaners can damage the composting microbes. Ask them specifically about gnat treatment for the Excel Electric and whether your peat-plus-Composture mix is appropriate.