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 (36)

  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?

      • I am having the same problem with alkaline bin. No matter what I add it stays at an 8ph. I used coconut coir, newspaper, cardboard, coffee grounds, and eggshells,leaves,and sawdust.Even feeding them veggies have changed nothing.
        I did purchase lime but even that didn’t change the ph. Help

  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!

      • Coffee grounds are ph neutral after the brewing process. Use a ph meter or litmus paper to check the used grounds to verify my statement. Just trying to help not be a smart a**.

  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!

    • Hi Megan, good question. My best guess is that freezing definitely kills off a percentage of the pathogens that may be contained in the eggshells. Baking them however does the best job of drying them so that they are super brittle and able to be pulverized as finely as possible. Either way, the worms get the benefit of the calcium and grit. Whichever way is most efficient for you is absolutely great!

  13. It’s here! My worm factory arrived today! My worms are supposedly on their way and should arrive in 3-8 days. I want to get started with having it ready, but I don’t want to start so early I have a smelly mess on my hands waiting for them to arrive and reduce the ideal environment. How far in advance should the bottom tray sit prepared, hours? Days? A week? Eager to get started but want the best chances for success!

    • Hey Jennifer, I am a 2-month veteran worm farmer having had great success for a first timer. I overcame a couple of issues: increasing moisture and air circulation at first, last week bin crawlers due to too much ice added for moisture, and now dealing with a possible PH imbalance which is why I’m on this site. If I were u, I‘d prep all ur dry bedding materials such as cococoir/compost/soil as ur base, worm castings inoculator, shredded newspaper and paper, cardboard pieces, dry leaves and grit. Then I’d wet it all down to condition ur new worm’s residence. This helps the existing microbe population get things going. This is what I did about 3 days before receiving mine which arrived in July with an 84F temp from shipping (!). Thanks to technology, I got news of their expected shipment arrival date so I was able to set their first frozen feeding buried in the middle section of the bin the morning I expected them to get delivered to my front door. BTW: there was a first shipment of worms that somehow got lost and it wasn’t for another week until I got the 2nd shipment. So I did exactly what I’m suggesting which is to just prep WITHOUT food the worm bin. Adding the food too far ahead of time could generate rot and a putrid smell to emerge if the wait is too lengthy. All the best to and ur little guys!

    • Hi Jennifer. Congratulations! You can get that ready right away! Just don’t necessarily add food scraps until the worms will be here sooner. As the tray sits, the microbes are populating the whole thing. Then when the food scraps are added the microbes will already be flourishing and can get right to the food so that it’s edible for the worms. Great question! Have fun

    • Hi Jennifer. Congratulations! You can get that ready right away! Just don’t necessarily add food scraps until the worms will be here sooner. As the tray sits, the microbes are populating the whole thing. Then when the food scraps are added the microbes will already be flourishing and can get right to the food so that it’s edible for the worms. Great question! Have fun!

  14. Hi! Just a couple quick questions. How often can I gently fluff up the worms environment, (organic garden soil and brown paper/cardboard) and does this motion cause stressors which would reduce breeding?

    I have my worms in my basement which is very moist and the soil compacts frequently.


    • Hi Kyle!

      Loosening up the worm habitat zone from time to time with a small garden hand rake can be a great way to resolve the compaction that naturally takes place over time. It promotes increased airflow, which is not only good for the worms but it also improves the effectiveness and speed of the worm composting process in general. Some recommends stirring the contents of the worm bin every week.

      However, there is definitely no need to completely mix up your worm bin contents. The worms themselves – along with various other critters do a lot of mixing on their own.

  15. Hi, I’ve noticed my worms are balling up and not moving much around the worm inn. Food is breaking down but I’m not sure if it’s the worms or just normal decomp.

    Googling says balling is most likely ph, parasites, or moisture issue. The bin is ideal moisture level of a wrung-out sponge. It may be acidic so I’m gonna add more neutrals and eggshells. Anything else you would suggest I check? I live in the south so it’s not too hot or cold right now. 50-70 most days and the bin is in a patio closet.

    • Hi Miranda,

      When worms group together, forming a ball, it may mean that they are unhappy. It could be a problem with the moisture in the bin, the acidity, or both.

      When it comes to maintaining the worm bin, we cannot assume that things are in order simply by appearance. That is why we need the aid of the thermometer, moisture meter, and pH meter to ensure that nothing is amiss.

      If you don’t have them yet, click here to purchase your meters.

      If you have any other questions, feel free to send us an email through our web form.

  16. Great information! Thank you so much!!
    My RW bin is 3 weeks old and seems to be going well. In am trying to not over feed as I have read that is the biggest rookie mistake.
    My ENC bin is 3 days old. I put them in the plastic tote bin (with screen covered holes on the bottom and on the sides) and left a light on. All the worms went under ground. (Yeah)
    Yesterday (day 2) I turned off the light and put the lid on the container.
    Fast forward a few hours and I go downstairs and there has been a mass escape!!
    We get up all we can find and turn the light back on.
    I have only feed them a very little amount of banana so I don’t think the PH is off. Bedding made from sterilized leaf mold, shredded cardboard, shredded newspapers and a small handful of black kow.
    I added some fresh newspaper on the top and laid cardboard sheets on top of that to give them a dry place if needed.
    This morning they are all down in the original bedding, not in dryer newspaper.
    I am leaving the lid off and light on.

    Do I just need to leave the light on longer? How long?

    I have the duel prong ph/light/moisture reader. It says that the ph is fine. I have tried reading tomatoe juice, lime juice, strong freshly brewed coffee, dried coffee grinds…..and the meter hardly moves.
    Without a chemical set is there a way to test it?
    Thanks for any help and advice you can give.


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