Clam Bake

This week in the Flog:

  • Another break from the balcony garden to show CalPhos preparation

I have the roach bin outside which is my cockroach composting tank. It is incredibly efficient in removing waste from the kitchen table. Just amazing.

But the roaches don’t eat everything. Over the last month we’ve had several meals with clams and shrimp. The roaches don’t eat the shells of the clams, and only partially get the shrimp shells. I’ve been piling the uneaten parts in the corner of the roach bin and now they’ve built up a bit. So I’m going to turn them into CalPhos!

Check out the roach bin with the shells piled in the corner. Haha time to clean house!

Calphos - Step 1

The roach bin and leftover clam shells

First I’ll grind them up a bit with the mortar and pestle. Not too much since I don’t want everything to burn when I roast them. But I think a little grinding is needed since they are thick clam shells not thin little egg shells. Here we go with the mortar and pestle:

Calphos - Step 2

The shells need to be ground up a bit for better roasting in the pan

And there you go, partially ground shells.

Calphos - Step 3

The shells are partially ground up after a few minutes of fun. These should roast nicely.

Now time for roasting. I’ll just put them in a pan with a nice flame below, like so:

Calphos - Step 4

Roasting on high flame in an old skillet

Roasting took about 15 minutes on high flame. It produced a lot of smoke and I kinda had to quit a little early for the sake of our nostrils. Not the most pleasant smell, smells like cat litter. After roasting, I have a nice selection of black, brown, and white calphos. There’s a little more white and less brown/black than I’d like – I guess this will be heavier on the Phosphorus and lighter on the Calcium. Oh well. It goes back into the mortar to be ground up real fine.

Calphos - Step 5

These shells are nicely browned after quite awhile on high flame

And there it is nicely ground up. It is practically dust, and only took 5mins or so. I love the mortar and pestle πŸ™‚

Calphos - Step 6

I ground up the roasted shells again to make them as fine as possible. This will help with the solvent step coming up next.

Now it goes into the plastic fermenting container. Gil recommends adding 5 parts vinegar. I don’t have quite that much right now so I’ll have to add a bit more later. Here it is just before adding the vinegar. Nice amount of calphos!!

Calphos - Step 7

Now vinegar will be added. The acid reacts with the calcium liberated through roasting in the previous step.

…and there it goes bubbling away as the acetic acid reacts with the calcium. It will bubble for some time, after which I’ll cap it and wait 20 days for the full extraction to proceed to completion. Here is the shot right after adding a bit of vinegar.

Calphos - Step 8

A simple acid-base reaction takes place which extracts the calcium that was liberated through roasting. Now we have bio-available calcium.

Wait 20 days…and I’ve got my fresh batch of CalPhos!

Calphos - Step 9

Look at that beautiful calphos. This will serve the plants well once they start transitioning to flower.

You can use many different materials to make calphos, clam shells being one good example. You can also use bones – bony fishes, animals, etc. Egg shells are another option. The shells of sea creatures like mussels, clams, oysters work well too. Crustacean shells have the added bonus of chitin, an amazing fertilizer in it’s bio-available form of chitosan.

  • This is Great! Thanks for the full photo tutorial, that really helps. I’ve been saving my pet chickens egg shells and can’t wait to try this.

  • Nance

    Do you test the pH before feeding the calphos solution to your plants?

    • Patrick

      I don’t test the pH although I know it it quite acidic from testing a long time ago. I don’t test anymore because of how I use it (very diluted, not mixed with a bunch of other stuff where I’m worried about overall pH, etc).

  • Karen

    great pictures, Patrick! so much easier to understand the process and use as a teaching aid. DAGHANG SALAMAT!

  • Henry


    For larger amounts, which I use to amend my used soil I came up with a quick way to crush the shells. I put them in a pillow case place them in my driveway and let my Chevy Blazer act as my Cuisinart.

    • Patrick

      Awesome! haha good tip as always Henry, thanks!


  • Henry

    Thanks Patrick,

    I posted a question yesterday in the fish fertilizer thread. It’s a reply to Manly Man that he made on Feb. 5th. Could you please read it and see if you can help a brother out.

    Thanks again.

    • Patrick

      I saw that I’ll reply now no problem Henry

  • Dan

    At what dilution rate would you recommend? Also do you know what the shelf life of this concoction would be around?

    Many thanks and keep up the good work.

    • Patrick

      You should be able to use it at 1tbsp per gallon. It will store for a long time, like vinegar. Not sure the limit on shelf life..

  • Phil Bradshaw

    Hi Patrick, I just found your site, after I was researching lactobacteria. I found a great recipe for “KWAS” made from rye flour, very simple!Posted by a Russian lady called Valarie Tsygikalo.
    I’m very interested in this calphos recipe, is the above dilution rate for use in hydroponics? I.e. 1 tblsp per gallon? Also, I’ve been looking at your other recipes, and would appreciate any info for dilution rates for use in a flood & drain situation. Thanks in advance.

    Phil B.

    • Patrick

      Hey Phil welcome to the site! Sorry for the late replies I’m still catching up with comments after being away. I replied to your other comment but anyway, try 5ml/l and go from there. I haven’t tried these in hydro but I’d love to and will do when I get some time.

      I’ll have to look for that KWAS recipe that sounds interesting.


  • Its a great knowhow for me about the homemade organic fertilizer. Everything natural, no chemical added.But is this organic stuff as effective as the chemical fertilizer? I am very lucky to have a glimpse of your wonderful stuff while flipping through the websites. Though I am not concerned with the farming,but I am encouraged to start my kitchen farming. In this regard your site wii be a great help. You are a lovely team contributing to the nature. Keep it up. I will remain in touch. Thanks a lot.


    • Patrick

      Hi Afzal,

      Thanks for your nice feedback. With regard to your question, organic farming can be as effective as conventional chemical farming.. but it takes a lot of practice and experience to get there. You just have to stick with it though and maintain a good perspective (this is an activity that enriches my life and the lives of those around me, as well as the environment I live in. If I struggle sometimes learning how to farm this way, it’s worth it). The end results will be well worth your effort.

      I’m so glad you found our site, good luck with your garden!


  • anne

    hi sir, I am a member of home farmers club, one farmer said we should use coconut vinegar (tuba) for fermentation. which is better sir?thanks

    • Patrick

      You can use coconut vinegar no problem! Anything acidic should work pretty well. Coco vinegar would be a great alternative to normal vinegar. It should be even better in fact.

  • HL

    Can I use water kefir or tibocos to replace vinegar to make calphos? Do I make a stronger water kefir or normal water kefir strength is enough to replace vinegar? I enjoy reading your websites and projects. Thanks for sharing. If I wud like to buy BIM from Gil, where can I purchase it?

    • Patrick

      Hi HL,

      pH of typical vinegar is around 2.5 whereas kefir is usually closer to 4.5, so you will have to use a lot more kefir than you would vinegar, or if you can let the kefir age so it is more acid that should work also. Not sure if kefir will get down to that pH, don’t have much experience with kefir.

      Should be very interesting to use kefir water, not sure how the microbes will do with the calphos – please let us know how it goes!


  • yash

    hello, i was wondering how actually fermentation is occurring here as we haven’t added BIM or lacto serum here so there wont be any microces there to direct fermentation in desire direction. please advice me if adding lacto serum to this can make fermentation better or not.
    thanks πŸ™‚

    • Patrick

      hi Yash,

      It’s not really a fermentation like the others, it is more a nutrient extraction. You are getting the calphos out through chemical reaction. No need to add lacto for this.


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