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 Problems with pine bark 
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Post Problems with pine bark
EDIT: Pine bark is still my preferred bulking material. In one unit I had an issue with resin being released, but in the end it was relatively simple to remove it.

Last year I tested pine bark mulch with excellent results, but apparently some pine bark contains high levels of resin which causes problems in a bio-composter. Between this year and last I've used four types/brands of pine bark. The bark from three of the bags worked fine, but the last one is releasing pine resin, causing juvenile larvae to migrate out. Most likely this is due to the resin making it difficult for the larvae to breath. One of my units using bark has a slight presence of resin, and one is thoroughly coated with it, including the harvest canister. I'll post photos tomorrow.

If you have a working composter using pine bark it seems best to remove it, although you may have used a batch that won't have the issue with the resin. If you choose to continue using the bark be aware that it wasn't a problem for the first month that I used it. My guess is that the temperature in the unit reaches a certain point where the resin will be released. My composter that has the heavy resin coating has been in operation for about a month, and the issue just became apparent yesterday. This is probably because the ambient temperature just started getting into the 90's, and the colony has recently become dense enough to generate additional heat. That particular composter is still processing waste, but it's certainly not ideal.

Edit: As I've worked with corn cob as a bulking material I'm finding that it drains much slower than larger material like mulch and charcoal. I think that will make it less desirable than other materials.

Previously I had good results using coconut husk chips (not the powder), and I imagine that other types of wood mulch will work well. A few days ago I began testing corn cob bedding, the type used for small mammals, and so far it looks good. Today I picked up eucalyptus and also melaleuca mulch, and I will begin testing them both tomorrow. I'm avoiding cypress mulch because it's being harvested faster than it can regrow. Melaleuca is an invasive species in Florida, and eucalyptus is grown as a crop specifically for mulch.

I don't think it will be difficult to remove and replace the pine bark with something else, but I want to do it myself before recommending a procedure. I'll be cleaning my composter tomorrow, and I'll post the results here very soon.

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Tue Jun 10, 2014 11:16 pm
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Post Re: WARNING: Problems with pine bark!
Thank you for the info.
I have two batches of new grubs from one day old to a week old. I had not introduced them to the composter yet.

:( However, I am sad to say that I cleaned my composter out this weekend of all the coffee grounds, pine back and charcoal and just put the grubs back in it by them self. I now know why there is a need of something in the composter beside grubs. They plug the drain. So I re-cleaned it yesterday afternoon and put charcoal and new rinsed pine back mulch and grubs back in it yesterday afternoon. :(

I am interested in how you get your grubs out of you composter. It took me all weekend long scoop by scoop straining out the coffee ground and then letting grubs crawl out of the pine bark.


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Wed Jun 11, 2014 8:34 am
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Post Re: WARNING: Problems with pine bark!
Sorry about the timing Robbie.

There may be a way to check a particular batch of bark to see if it has the resin issue. It might be as easy as soaking it in very warm water for a while and seeing if any resin is released. I wouldn't bother with that if I was starting from scratch, but since you already have your composter set up it might save some extra work. I'm only guessing that high temperature was what caused the resin release. It seems reasonable, but there may be other factors.

I've used pine bark with excellent results most of the time in the past, so all pine bark is not the same. You can choose to stay with what you now have and just keep an eye on it for signs of a problem. If the issue develops later, after you have a dense population of BSFL, then you wouldn't have to worry about losing a small percentage of the larvae during a cleaning operation. The thing to watch for is a film that sticks to the walls of the composter. It makes it look a bit hazy. Of course the migration of juvenile larvae is another sign, but that can also be caused by high temperatures in the waste so it's not a foolproof indicator.

I'll learn more today and post the results tonight.

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Wed Jun 11, 2014 10:05 am
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Post Re: WARNING: Problems with pine bark
Pine bark releases tannin which can interact with protein & amino groupings of living cells it encounters. For example for tilapia fish the tanin inhibits rate the fish feed & over time their growth diminishes. It is partly due to how tannin coalesces & affects cellular enzymes; being that enzymes are proteins.
Larvae have symbiotic micro-organisms & these will be both inside as well as on the outside. The conditions of the bark source of tannin makes a lot of difference & depending on how the tannin compound forms in contact with air the alteration (polymer) will either be toxic or rendered non-toxic to micro-organisms.
If the tannin forms into a polymer that can make hydrogen linkages to enzymes (proteins) this can damage the larval symbiont. But if the tannin polymer that gets formated isn't suitable to pass into a micro-organism it won't be problematic. As per (1992) "Toxicity of Tannic Compounds to Microorganisms", Basic Life Sci., Vol.59,pgs. 673-692.
Anaerobic conditions affect tannins too. But in anaerobic circumstances it is a function of the pH & duration of that pH which influence modification of tannin characteristics.


Wed Jun 11, 2014 1:22 pm
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Post Re: WARNING: Problems with pine bark
I hope that any issues that might be caused by tannins would be lessened by the regular flushing.

For anyone just starting a colony, and who has only a few thousand small BSFL, I would recommend waiting until you have egg laying in your composter before removing the bark. Losing a small percentage of small larvae won't be a big issue once you have regular egg laying and good start on a dense colony, but disrupting the system before then could set you back. Of course, if you don't have any larvae at this time it's a good idea to remove the bark.

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Wed Jun 11, 2014 2:30 pm
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Post Re: WARNING: Problems with pine bark
Jerry,
Please do not worry about it. I did rinse the pine back mulch before I introduced it to the composter. I am at this moment soaking some in hot water to see if any resin shows up.

I appreciate your hard work, testing and research and look forward to your results.


Wed Jun 11, 2014 2:36 pm
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Post Re: WARNING: Problems with pine bark
Thanks Robbie! :)

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Wed Jun 11, 2014 2:39 pm
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Post Re: WARNING: Problems with pine bark
There may be a simple solution, but I won't know for a day or two, until the current test is completed.

First, I tested Dawn Ultra X2 dish washing soap and found that it cut the resin easily. Then I filled the effected 12 gallon composter to the maximum level with slightly warm water (don't exceed 100ºF/38ºC) and added 6 ounces/175ml of Dawn. I then gently agitated the contents with my hand, and wiped the walls with a simple kitchen sponge. I drained the liquid, refilled with clear water, and drained again. I passed the liquid through a wire mesh kitchen strainer to catch the larvae which had washed out, and returned them to the unit.

I couldn't stay to observe the results due to a severe thunderstorm that was passing through, but all of the larvae I observed after the "bath" were still very mobile. Perhaps later today I can go back to the farm where I keep my BSF and see how they're doing. If not, I'll check them tomorrow.

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Wed Jun 11, 2014 4:51 pm
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Post Re: WARNING: Problems with pine bark
First of all, no worries about the burgeoning issue with pine bark. I totally understand the trial and error nature of this kind of diy engineering, and there are limitless ways in which things can surprise. It's all just a process, and as we go, we learn.

We have eggs in our unit (the small size) that have been laid on top of burlap that we use to prevent house flies from laying directly on the scraps. I can't tell yet whether the pine bark is a problem (our colony of larvae is small) but I am seeing a handful of larger, dead larvae (unless I'm mistaking dormant ones for dead).

I am considering removing the pine bark and adding gravel in its place, to just above the horizontal perforated drain pipe, then burlap on top of it. Thoughts on whether this would be advisable. If not gravel, perhaps just course, single ground mulch? The idea is really to keep the unit aerated and the pipe unclogged, yes?


Thu Jun 12, 2014 12:57 pm
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Post Re: WARNING: Problems with pine bark
Edit: As I've worked with corn cob as a bulking material I'm finding that it drains much slower than larger material like mulch and charcoal. I think that will make it less desirable than other materials.

Hi tbirdwilson, and thanks for joining the forum to share your questions.

Quote:
We have eggs in our unit (the small size) that have been laid on top of burlap that we use to prevent house flies from laying directly on the scraps. I can't tell yet whether the pine bark is a problem (our colony of larvae is small) but I am seeing a handful of larger, dead larvae (unless I'm mistaking dormant ones for dead).

I'm very glad to hear that you have egg laying. That means the hard part (the waiting) is over. :)

Statistically speaking, there is about a 20% chance that the larvae you're seeing are dead. That's based approximately on the number of times that people have told me they were observing dead larvae, only to find out later that they were not dead. This is especially true if the immobile larvae are below the surface, against the wall of the unit. They often rest like that as you can see in a photo in my previous post. The large vertical larvae below the surface in that photo were stationary at the time, but were very much alive. If you see larvae that you believe may be dead, I recommend isolating them and checking on them later to see if they've moved. If the weather is on the cool side, you can also hold one of the larvae in question in your hand to see if warming it will cause it to move.

Quote:
I am considering removing the pine bark and adding gravel in its place, to just above the horizontal perforated drain pipe, then burlap on top of it. Thoughts on whether this would be advisable. If not gravel, perhaps just course, single ground mulch? The idea is really to keep the unit aerated and the pipe unclogged, yes?


Yes, the basic function of the bulking material is to keep the waste aerated, and in my mind, using as much bulking as possible (50% of the volume) results in better aeration.

I started out using lava rocks in this system, but quickly decided they did very little to enhance function. I think smooth rocks are even less beneficial. The lava rocks served to give some structure to the waste, but wood, charcoal, corn cob, coconut husk, etc. do more than just that. Since they're absorbent they work as a moisture buffer; they soak up excess liquid if it's present, and they also retain moisture if the waste is drying out. (BSF thrive in high moisture environments) Also, porous materials have potential for supporting beneficial bacteria.

I'm not a biologist, but my understanding is that it's good to give beneficial microbes a matrix to live in. The porous materials I mentioned seem suited to this, but of course rocks are not well suited. I have some customers who are experimenting with all-charcoal systems, and I think that has great potential because it seems like a good way to charge it (biochar) with liquid and microbes.

I understand being reluctant to fill a new composter with so much inert material, however if you use too little I think you're detracting from the filtering aspect of the design. I always start out with at least 1/3 of the volume filled with mulch/coir/charcoal etc., and I haven't run out of room to compost during any season, even with fairly heavy feeding. In the photo below you can see where I marked the waste level each time I added 2 lbs/1kg of food. Keep in mind that when I started this unit, the mulch was almost to the level of the first mark. Notice that the level on 9/21 is lower than that on 9/10. The waste would rise and fall depending on how often I fed, what type of food, and the make up of the colony. After four months of fairly heavy feeding (over 100 lbs/45kg) the waste was still at about the level it was in the photo. This is because by regularly flushing the unit I was washing out very fine solid material. The flow of waste through the unit reached a balance where the input and output were roughly equal.

Please understand that I encourage people to experiment with this design. I have a lot to learn still, as this topic illustrates. :) So, don't hesitate to follow your ideas if you like, and hopefully you can report what you find and we'll all learn more.

Image

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Thu Jun 12, 2014 2:10 pm
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Post Re: WARNING: Problems with pine bark
What I posted about dead larvae may have come across as a little defensive. I've been shipping a lot of BSF eggs lately and it's very common that people assume they're dead, when they're actually not. I hope no offense was taken tbird, you framed your opinion about the larvae in a very open minded way, and I hope to hear more about your project going forward. :)

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Thu Jun 12, 2014 11:00 pm
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Post Re: WARNING: Problems with pine bark
I checked the composter today and it appears to be normal. I don't see any resin, and there were several BSF females laying egg in it. I flooded and flushed it again, just to get rid of more Dawn residue, but I'm going back to my normal schedule now. I should mention that the bucket of effluent (waste water) that sat for 18 hours after the initial rinse, contained many dozens of larvae that were apparently very healthy. I strained them out and added them back to the composter.

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Fri Jun 13, 2014 10:52 pm
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Post Re: WARNING: Problems with pine bark
No offense taken whatsoever, Jerry. I see what you mean about soldier fly larvae's tendency to "rest."

Though I saw no evidence of resin or early migration, I went ahead and removed the pine bark nuggets. The colony appears very healthy. I was particularly impressed with the baited plastic container I used with corrugated cardboard inside it. Huge number of eggs and tiny larvae.

I decided to go ahead and lay in 3-4 inches of small rocks (slightly larger than gravel) over the pipe, then layered landscape cloth in above the rock. I also made a cylinder of landscape cloth and surrounded the vertical section of pipe, too. I'll periodically flush the harvester and drain the leachate into tubs of biochar and mulch over time.

Good stuff...very exciting to have this system up and running.


Sat Jun 14, 2014 3:24 pm
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Post Re: WARNING: Problems with pine bark
Thanks tbw, sometimes communicating via text can be problematic. ;)

I'm looking forward to seeing how your setup works. My guess is that the meshes you're using will become clogged, but of course I could be wrong about that. There is certainly no harm in trying different configurations and at the very least we might learn something.

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Sat Jun 14, 2014 3:48 pm
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Post Re: WARNING: Problems with pine bark
So far everything look good in my Bio-C. I have flush it everyday. The first couple times it was clear and now turning brown red color water, which I would think that is from the Pine Bark. The grubs are eating.

Today I combined two baby BSFL groups together. They are from 5 days to 2 week ago. I was not sure how safe it is to move them to the Bio-C or just to a big container till they get bigger, they contain is getting very liquidity. see photo.


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Sat Jun 14, 2014 10:00 pm
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Post Re: WARNING: Problems with pine bark
Robbie, you should be able to reduce the frequency of flushing now. My current thinking is that it should be done "as needed", which in most cases will be about once a week, or maybe a little more if you process a lot of waste. I have a theory that black soldier fly larvae process food so thoroughly by eating it several times. If that's true, then excessive flushing will have the effect of rinsing away material that the BSFL would have otherwise eaten.

If you don't flush your composter for the next 5 or 6 days you could add the new larvae now, and by the next flush they will be large enough that not too many will be washed through, and those that are will be easy to strain out.

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Sun Jun 15, 2014 8:45 am
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Post Re: WARNING: Problems with pine bark
Here's a video of the composter three days after the Dawn Ultra treatment:


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Sun Jun 15, 2014 9:50 am
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Post Re: WARNING: Problems with pine bark
Quick comment concerning dead grubs. The few I have found are always very bloated, much like animals do. Never have I picked a normal looking one to find it dead, they have always began moving again after resting in my hand several seconds.


Wed Jun 18, 2014 3:29 pm
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Post Re: WARNING: Problems with pine bark
After a while you learn to spot them fairly quickly.

I checked this composter yesterday and you would never know there had been a problem. I'm thinking that a Dawn Ultra treatment would also solve the problem of excess fats clogging the system and making it difficult for the larvae to breath...

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Wed Jun 18, 2014 4:36 pm
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Post Re: WARNING: Problems with pine bark
That is an amazing difference in the viewing! :mrgreen:


Thu Jun 26, 2014 5:00 pm
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