Pot worms and cat poop in a worm bin

by Ryan
(San Diego CA)

Hello,

I have been feeding cat poop almost exclusively to my worm bin and have noticed lots of pot worms. Dried it out, added more carbon and even calcium carbonate but no change. The worms seem happy though. Is the poop creating too acidic of an environment?

Thanks,
Ryan

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Aug 04, 2025
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starstarstarstarstar 		Re: Pot worms and cat poop in a worm bin
by: Stephan

Feeding cat poop in moderation to a worm bin is in my opinion, quite ok. However, feeding it almost exclusively to your worm bin is likely contributing to an imbalanced and potentially problematic environment, even if your worms (likely red wigglers) appear "happy." The presence of pot worms (small, white worms like Enchytraeidae) suggests an overly moist, acidic, or nutrient-rich environment, as they thrive in such conditions. While worms may tolerate cat poop it’s not ideal due to its high protein, fat, and ammonia content, as well as potential pathogens like Toxoplasma gondii. Below, I’ll explain why to much cat poop may create an acidic environment and provide step-by-step instructions to safely continue using it while maintaining a healthy worm bin.

Why Cat Poop Causes Acidity: Cat poop, as a carnivore waste, is nitrogen-rich and can lower the pH of the bin, creating an acidic environment. Pot worms are more tolerant of acidic conditions than composting worms, which explains their proliferation.

Excess Nitrogen: The high protein content in cat poop leads to excess nitrogen, causing ammonia buildup, which can stress worms and contribute to acidity.

Moisture and Decomposition: Cat feces decompose slowly and retain moisture, fostering anaerobic conditions that favor pot worms and produce odors.

Pathogen Risk: Cat poop carries health risks (e.g., toxoplasmosis), so any compost used on edible plants or handled directly requires caution.

Your attempts to dry out the bin, add carbon, and use calcium carbonate are good steps, but the exclusive use of cat poop likely overwhelms these adjustments. Below are tailored steps to balance the bin while continuing to use cat poop, though I strongly recommend reducing its proportion and prioritizing safety.

Step-by-Step Instructions to Feed Cat Poop to Your Worm Bin

Safely Step 1: Assess and Adjust Bin Conditions, Goal: Correct the acidic, moist environment and reduce pot worm dominance.

Actions: Test pH: Use a pH meter or test strips (available online or at garden stores) to check the bin’s pH. The ideal range for worms is 6.0–8.0. To much cat poop likely pushes it below 6.0.
Add More Carbon: Pot worms thrive in nitrogen-heavy, moist bins. Add dry, high-carbon materials like shredded newspaper, cardboard, dry leaves, or straw (2–3 times the volume of cat poop). This balances the carbon-to-nitrogen ratio (aim for ~30:1).

Increase Aeration: Stir the bin gently with a trowel to improve airflow and prevent anaerobic pockets. Ensure the bin has adequate drainage holes and a breathable lid.
Add Calcium Carbonate Sparingly: You’ve added calcium carbonate, which neutralizes acidity.

Apply it lightly (1–2 teaspoons per square foot of bin surface, mixed in) every 1–2 weeks, monitoring pH to avoid over-alkalizing (pH above 8.0 harms worms).

Step 2: Limit and Pre-Treat Cat Poop, Goal: Reduce the risks and imbalance caused by cat poop while still using it.
Actions: Reduce the quantity: Limit cat poop to 10–20% of total feed to avoid overloading the bin with nitrogen and pathogens. Supplement with vegetable scraps, fruit peels, coffee grounds, or grass clippings (no pesticides).

Pre-Compost Cat Poop: Before adding to the worm bin, pre-compost cat poop in a separate, hot compost pile (aim for 55–65°C/130–150°F for at least 3 days) to kill pathogens like Toxoplasma gondii. Use a dedicated pet waste composter or a small outdoor pile with carbon materials (e.g., sawdust, leaves). Only add pre-composted material to the worm bin.

Remove Litter: Ensure no cat litter (clay, silica, or even biodegradable types) enters the bin, as it can harm worms or disrupt decomposition. Sift or manually remove litter before composting.

Bury Small Amounts: When adding cat poop (pre-composted or fresh in small quantities), bury it in pockets within the bedding, 2–3 inches deep, to prevent odor and pest attraction.

Step 3: Manage Pot Worms, Goal: Reduce pot worm populations without harming composting worms.
Actions: Dry the Bin: Pot worms thrive in wet conditions. Reduce moisture by adding dry carbon materials and ensuring good drainage. Aim for a bedding consistency like a wrung-out sponge (60–70% moisture). If the bin is too wet, pause adding cat poop for 1–2 weeks.
Lower Acidity: Continue monitoring pH and adjust with calcium carbonate or crushed eggshells (1 tablespoon per square foot, mixed in) if pH remains below 6.0. Pot worms prefer acidic conditions, so maintaining neutral pH discourages them.
Starve Them Out: Temporarily stop adding cat poop and feed only carbon-rich materials and low-nitrogen scraps (e.g., lettuce, apple cores) for 2–3 weeks. This reduces the nutrient overload that pot worms feed on.

Step 4: Monitor Worm Health, Goal: Ensure your worms remain active and healthy.
Actions: Check Behavior: Healthy worms (e.g., red wigglers) are active, congregate near food, and reproduce. If they’re sluggish or avoiding the cat poop, it’s a sign of stress.

Inspect the Bedding: Ensure bedding (shredded paper, coconut coir, or leaves) is fluffy and not compacted. Replace 25–50% of bedding if it’s slimy or foul-smelling.
Feed Sparingly: Feed only what worms can consume in 1–2 weeks (about 0.5–1 lb of food per pound of worms weekly). Overfeeding cat poop exacerbates acidity and pot worm issues.

Step 5: Implement Safety Measures, Goal: Minimize health risks from pathogens in cat poop.
Actions: Always wear gloves when handling the bin or compost to avoid contact with pathogens.

Avoid Edible Crops: Do not use compost from a cat-poop-heavy bin on edible plants (e.g., vegetables, herbs) due to pathogen risks.

Use it only for ornamental plants or non-edible landscaping.

Wash Tools and Hands: Clean all tools, bins, and hands thoroughly after working with the compost to prevent cross-contamination.

Consider a Separate System: For long-term cat poop composting, set up a dedicated pet waste composter (available online for $50–150) to process cat feces safely before adding small amounts to the worm bin.

Step 6: Maintain Long-Term Balance Goal: Create a sustainable system for using cat poop while keeping worms and compost healthy.

Transition to harvest Compost Carefully: When harvesting vermicompost (every 3–6 months), screen it to remove undigested cat poop or litter residue. Store compost in a sealed container and let it cure for 1–2 months before use to further reduce pathogens.
Monitor Pot Worms: If pot worms persist despite adjustments, reduce feeding frequency and increase carbon until their population declines. They’re harmless but indicate an ongoing imbalance.

If you have further questions, please feel free to contact us again.

Kind regards and God's blessings

Stephan Kloppert

Author of "How to start a profitable worm business on a shoestring budget"

Editor of www.worm-composting-help.com

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