How To Check & Manage pH In Your Worm Bin

How To Check & Manage pH In Your Worm Bin

What is pH?

pH, also known as power of Hydrogen, is a measure of the acidity of a substance. It is measured on a scale from 0 (acidic) to 14 (alkaline). A substance with a pH of 7 is considered to be neutral.

The farther an item’s pH is from 7, the more reactive it is, with the most reactive substances having a pH of 0 or 14. These substances are strong enough to cause severe burns on the skin. Naturally, a chemical property that can cause burns should be carefully monitored to ensure the health of your worms.

What are the dangers of mismanaging my bin’s pH?

A mismanaged worm bin pH can be disastrous to your worm population. Minor pH issues can lead to sour odors coming from your worm bin, much like the smell of vinegar.

If conditions continue to worsen, your worms will begin to show signs of “protein poisoning.” Worms with protein poisoning will crawl along the surface of the bin instead of burrowing within their bedding. When conditions get bad enough, your worms will become scraggly and deformed, and eventually die.

You can tell that the conditions in your worm composting bin are becoming problematic if you notice your worm population trying to crawl up and out of your worm bin with no noticeable cause. You may not be able to immediately pinpoint the specific issue that needs to be dealt with, but you will at least be alerted to the fact that something is not right, and corrective action needs to be taken.

What pH is best for my worms?

It is good for the pH in a worm bin to be pretty close to neutral. A properly maintained worm bin should have a pH measurement between 6.0 and 7.0, which is perfect for many types of composting worms. Most species of composting worms can handle pH conditions up to 8.0, but its always best to play it safe and try to maintain a pH in the 6.0-7.0 range.

How do I check the pH in my worm bin?

It is surprisingly easy to check the pH in your worm bin when you have the proper equipment. You can use a pH meter like the one offered here to quickly and accurately test the pH in your bin. Simply insert the probe into your worm bedding and wait a few seconds. The pH measurement will display on the top of the meter for easy reading.

You should make sure to test the level in a few different locations within the bedding, in order to account for the potential existence of small acidic pockets in the worm bin.

If you don’t have a pH meter, or you need to check conditions right away to handle a worm emergency, you can always rely on a simple smell-test. Does your bin smell wet, musty, rotten, or mildewy? If so, you very likely might have pH issues.

Note that the mere presence of odors in your bin is not a sure sign that your bin’s pH is the issue. Odors can also be caused by overly-compacted bedding material or excessively moist conditions inside the worm bin.

Handling problematic pH conditions

When dealing with problematic pH conditions in your worm bin, there are a few different corrective actions you can take.

The first course of action you should take is to sprinkle some crushed eggshells around your worm bin. The eggshells are pH neutral and will help to bring your overall bin pH closer to optimal levels.

NOTE: It is important to bake your eggshells in the oven in order to remove any pathogens that may be present on the shells. I like to bake mine at 400 degrees for about 20 minutes. It also makes the eggshells easier to pulverize into bits that are small enough for your worms to ingest.

Crushed limestone can also be added to the worm bin in place of the eggshells if you happen to have any lying around. Crushed limestone is NOT to be confused with hydrated lime, which WILL kill your worms.

If your issues cannot be resolved with eggshells or crushed lime, there are a couple emergency steps that you can take.

  1. Improve airflow in the bin by removing the lid if applicable and placing a fan nearby.
  2. Mix some fresh bedding into the existing bedding to bring the pH closer to the neutral level of the fresh bedding.
  3. Aerate your worm bin by turning the bedding and breaking up any compressed pockets that you find.

With these steps, you should be able to solve any pH issues that you may face. Your worms will be much happier and healthier with a properly managed worm bin! If you know of any other techniques to help neutralize the pH in your worm bin, please let us know in the comments section below! If you don’t yet have a pH meter, check out our affordable and easy to use pH meter here.

Happy composting!

Article by Donny B

Readers Comments (24)

  1. Thank you for this great information. I am in a bit of an emergency. I am not clear if I am supposed to mix the eggshells into the bin or sprinkle them on the top? I have moved the worms back and forth three times and they are not happy campers. 🙁

    • Mixing in the eggshells is a good idea if you are using them to correct a pH imbalance.

      If you are just adding the eggshells for grit, you can simply sprinkle them on top of your worms’ bedding and call it a day!

    • I never mix them in, just make a layer of them and the worms mix them When I clean my compost up after drying it, then I crush them

  2. Should I make a habit of turning over the worm bed every few weeks as to get more oxygen in it ??

  3. Can i freed cashews no ky worms?

    • Hi, Trish! Red wigglers have no teeth and rely on both chemical and physical decomposition to get their food easily ingestible. If you were to blend your cashews very well before serving, your worms could enjoy them in moderation without any complications. For more useful information on what red wigglers can eat, check out this handy infographic. We have turned it into a magnet that can be kept easily accessible for it whenever you’re in doubt.

  4. The PH in by bins is between 7 and 8. What is the best way to bring it down?

    • Hi, Thom. First I’d like to assure you that if you are hovering just a little over 7 and up to 8, your worms should be doing just fine. However, I’m glad you want to be so careful and are interested in keeping as close to neutral as possible. So, to lower the pH in your worm bin, I suggest adding fresh coffee grounds a bit at a time. Mix it in well, such that the moisture can balance before you retest. Use your pH probe meter and add more grounds if you need to until you reach that sweet spot. Best to you!

      Quick question- I’m curious, what type of bedding and feed you use that may bring the pH toward being alkaline?

  5. Thank you for your useful stuffthank you for

  6. My worm bed is at a level 8, and I need to bring it down quick. What of the three things in your article would work best?

    • Hi Tim. Don’t worry too much. A pH of 8 is not so harmful that your worms will suffer terribly until it’s back to a 7. 1. Incorporate crushed eggshell. 2. Aerate 3. Allow the bedding to dry out a bit.

  7. Help! The pH of my worm bin is too alkaline and I’ve already lost some worms. How do I lower it back into safe neutral range before it’s too late?

    • Hi Christine. To balance out an alkaline bin, you are going to want to add materials that lean toward being acidic. Coffee grounds are a good choice if you have used ones on hand. Peat moss is another acidic material you may have laying around for garden projects. Aerate and combine both acidic and neutral bedding to help dissipate the alkaline materials. Best of luck to you!

  8. Hi my worm PH reading is at 5 (there are no acidic foods in there) when I open the bin in the morning the inside of the lid is really wet. I have added egg shells and reduced scraps with high water levels but nothing has changed. I have also mixed newspaper & egg cartons into the bedding. I have notice red mites every now and then. My worms are not happy but I don’t know what else to do.

    • Hi Heidi, I’m so sorry for your frustration. Right off the bat, I suggest letting your bin dry out a bit. Let the lid stay off for a day or so. Aerate the bedding to let any accumulated acidic gasses out, and let the air help evaporate whatever excess there is. Use a moisture meter to monitor the progress and stop when it reads 80%. Incorporate more well-shredded newspaper or paper egg carton. Adjusting the pH balance by adding more neutral matter is maybe the fastest way to help things along. If you still find that your bedding reads very acidic, it may be worth checking with a second meter. If still needed- keep adding well-dried and pulverized egg shell. Best of luck to you and your worms!

  9. My worm cultures seem to be melting. The worms are distributed throughout the culture, it has been growing nicely for three weeks or so, and then the worms just melt where they are – they don’t migrate to the top, they melt where they are. This has happened twice with recently purchased cultures that I made no modifications to – no new soil, just fed with milk soaked bread. Any ideas?

    • Hello Joe. I do have an idea. Stop feeding them milk-soaked bread! It is always best to avoid all animal products, excluding egg shells. Also, bread becomes a mushy yuck in the worm bin. I assume that there is some kind of reaction happening as the milk and bread break down. You can think of your worm bedding as if it were garden soil. Milk and bread don’t come out of the soil- they shouldn’t go into it either. Instead, fruits, veggies, and clean paper products are best. Check out our colorful What Can Red Wigglers Eat infographic magnet for a quick reference! Follow these guidelines and you’ll be back on track in no time!

  10. My worm bin has been going for about 6 weeks and stays right between 7 and 8 pH. I add dried powdered eggshell and dried paper whenever I feed them. Today I also sprinkled some azomite on top of the bedding, then tried to fluff up the bedding a bit because it was getting matted down at the bottom (it’s starting to get full and heavy). When I pulled up some of the bottom bedding, there were some dead baby worms. So sad. 🙁 Are they less hardy than the mature worms? If so, what can I do to make life easier for the babies?

    • Hey Diana, sure they were dead? I don’t mean to sound condescending- I find that cold worms in particular sometimes don’t move much. Sometimes I fear I’ve killed them and then realize they’re just sleepy or chilly. Also, dead worms fairly quickly dissolve into the mix (sorry). Anyway, my experience is that I am always amazed at how hair-thin babies can survive at all. But of course they are likely more susceptible to certain stressors- salt may be an issue. Especially at the bottom of your bin. It sounds like you are being careful though… Your pH sounds totally solid. Maybe just keep a gentle fluff allowing air to get throughout. Otherwise…? Not sure. Please let us know if you find something out.

    • Hi Dianna. Ah, I feel for you woman! The endgame question. As if the journey weren’t part of the adventure. Alas. You go forth and teach that man the wonders of these little magicians of the earth! I stand beside you with a similarly worm-ambivalent man of my own. You are right, the garden produce and blooms will soon make him a convert! Worm composters unite! Men and women alike! ( : Have a great day.

  11. Hi Fracesca.
    Ash lowers the PH of the soil.yvonita

  12. Hi! Thanks for all the info. One question – I have been adding egg shells to my compost, and I’ve been freezing them first with the rest of my produce scraps beforehand. But I have never baked them, this is the first I’ve heard of that. I’m wondering if freezing them would also kills the pathogens in question – does that make baking the eggs unnecessary? I blend the egg shells before adding, to help break them down, but I am curious. I’ll give baking them a try next time!


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