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Notes on leaving flow super over winter


The next step is to figure the best way to clean these frames? Any one have any ideas? I tried blasting one with a high pressure cleaner- it helped a bit but was not as effective as I hoped. I’m figuring I’ll soak them in warm water- and some agent to clean the mold off. Is a bit of bleach a bad idea?

We had some questionable ‘darker’ cells in some of our empty flow frames after a condensation heavy winter last year. The previous winter (2016) we left the super on with no such condensation issues but the bees seemed to store more honey in them that winter and also the hive was in a spot receiving more sun but had to be moved to a less favourable position due to an unhappy neighbour.

Anyway, it was a little fiddly, but last year we took the frames with darker cells out in early spring and washed them in warm water with a very diluted detergent and used a manual method (stainless steel straw cleaner brush poked in) to clean up the affected cells. Then gave the frame a good rinse and dried it out before putting back in hive. Lots of wax stayed intact in the cell gaps so the bees didn’t have to start from scratch. The frames came up nicely and haven’t had the problem again this winter as I’ve managed the condensation a little better with ventilation.


Did you literally have to poke your brush cleaner into each and every cell? :sleepy:


Yep :expressionless: but it was only the columns of cells towards the ends, rather than the ones in the middle of the frame that seemed to mostly affected…and not all frames, so it wasn’t tooooo bad a job.


I have some frames where it’s all over. Won’t be fun. How many thousands of cells per side?

I’m gonna see if I can figure something easier. I’ll try with my high pressure cleaner again too.


I agree, that would be madness to manually clean that many cells. Maybe a soak then the high pressure cleaner will do the trick?


A few people on the forum have tried different cleaning techniques:

I remember @busso put them in the dishwasher which seemed to help the Flow Frames, but left a big lot of gunk in the machine.

Our Cleaning/Sterilisation faq has been updated on our website:

I know it refers to a few other things other than mold, but thought you might find the chemical information useful anyway.

Under normal conditions, it is not necessary to clean your Flow Frames (click here for information on routine cleaning and storage of Flow Frames).

In some jurisdictions cleaning may be necessary prior to sterilisation as a means of disease control—please contact your local department of primary industries for region-specific advice.

Cleaning and wax removal for sterilisation

Following are some options for removing wax and propolis from Flow Frames. We have tested these treatments and found them to have no effect on the mechanical function of the product.

Prior to treatment manually remove excess wax, by placing the frames on newspaper and scraping. We have achieved best results at wax removal by disassembling the Flow Frame prior to treatment, however, please note that this will void your warranty.

These are maximum exposure recommendations and should only be used under conditions where sterilisation of the frames is necessary. Do not exceed temperature and time for optimum function of your frames. Destroy all debris by burning.


#Ethanol is highly flammable. Do not heat ethanol on or near a naked flame.
*The use of casutic solutions (Caustic Soda/washing soda) requires great care and caution. You must use suitable protective clothing, protect your eyes and use rubber gloves.

The safety of your bees is very important—after any treatment of your frames please ensure they are rinsed thoroughly in water and dried prior to storage or returning to your hive.


Please note that if you are treating AFB this is a notifiable disease. Legal requirements differ between jurisdictions. Please contact your local authority for advice on appropriate disease control measures.

Bleach treatment:

In some jurisdictions, it is acceptable to use bleach to sterilise AFB contaminated hive components. Research has shown that immersion for twenty minutes in a solution of 0.5% sodium hypochlorite kills AFB spores and other bacteria. The solution must be in direct contact with the spores. It is, therefore, necessary to remove wax and other debris prior to sterilisation (see above cleaning options).

Gamma Irradiation:

In some countries, Gamma irradiation is used to sterilise equipment infected with American Foulbrood (AFB). A dose of 10 kGy is sufficient to eliminate AFB spores (Hornitzky&Wills, 1983; Australian Honey Bee Industry Biosecurity Code of Practice, 2016, Pg 11). Flow Frames can withstand a maximum of 20 kGy Gamma irradiation, above this, the plastic will become brittle and the mechanism may fail on harvest.

What you should do when treating with irradiation:

Flow Frames should be exposed to a maximum combined dose of 20 kGy irradiation. This enables 2 rounds of AFB sterilisation at 10 kGy. Some Irradiation facilities use beehives as ‘gap filler’ in larger loads. This means a single round may expose your frames to more than 40 kGy.

We recommend you contact the facility to discuss maximum doses. If you are in Australia (excluding Tasmania) we recommend that you send your frames to Steritech’s Brisbane Facility. This facility is capable of controlling the irradiation dose. If you need to send your Flow Frames for irradiation please mark them clearly for future reference.

Can flow hive frames be sanitized after pests?

Great to see these updates @Faroe


Just for interest. I have left my Flow Super on over this Winter. I robbed only once this year with about 18Kg and the Flow was back to about 50% full when the main nectar flow finished. That 50% has not changed much, maybe down a bit. This week in one frame, the bees will fill and cap 90% of the cells, next week they will uncap and not so much consume a lot of the honey but just seem to shift it around to another frame and cap it.

Very hard to do a lot of monitoring because of cool weather however looking through the windows the hive has lost no vigour and honey stocks fairly constant.
We do have the advantage of having good sources of nectar and pollen all year and on days when its not too cold, or windy or rainy the bees certainly are out in force. Have a couple of months yet before the spring blooms but I am confident the leaving the Flow on over Winter succeeded. I am planning to extract all the honey in the Flow mid/late Spring to be ready for the Marri flow of nectar which is our main source of honey for the year.

I caution, that leaving the Flow on in other areas and climates may detrimental to the hive and in most cases should be removed over Winter…


I am guessing our climates would be similar and a few weeks ago I fitted my two flow supers and conventional supers on the rest of the hives, although it is winter the bees have been increasing the pollen and nectar in all the hives and no reduction in bee numbers.
I guess one mans winter is another mans summer. Today I did a split of a hive, brood and super, which if left much longer it would likely have swarmed. Here there is pollen and nectar foraging for all the year.


that’s a good idea to soak them first! that just might do the trick. Cheers!

Here are some pics- the empty frame is from the same hive as the full one. As you can see the empty one is far more affected. Obviously the honey in the wax forms a physical barrier, but you can see how the mold has not gone on to the surface of the capped honey, so I think that wax itself has anti-mold properties and the honey too no doubt.

It’s not pretty these frames are only18 months old.


Have you tried soaking in warm Caustic Soda, or sodium hypochlorite yet?


Jack, I would be surprised if that mould didn’t disappear if you soaked it in napisan/sodium hypochlorite for a few minutes.


Wow, that is a name I haven’t heard in over 50 years. :blush:


A household name in Australia still :slight_smile: Grew up with my step mum saying - “just soak it in some napisan” :fairy:

Although, I must say - I do not know of the exact ingredients in Napisan, maybe it is not just Sodium Hypochlorite. So, it would be best to check the ingredients and concentration before using on your Flow Frames.


Hi @semaphore Jack, after I read your post and went to open up my hive in Melbourne backyard, found a same problem as yours… I left 25% honey spread over 4 frames since end Feb, they either moved down to the brood box or have eaten most of the top flow frames honey and only has a handful size of capped honey left there until today… The 2 outter frames are getting moulds too, especially the one that has no sun… So I took all off and extracted the remaining honey and clean…

Initially I used 70C water with a tiny bottle brush to scrub in the laundry sink but going no where …i then used 100C boiling water from the kettle, it melt quickly the wax but some stubborn mould at the base wouldn’t come off so I resorted to the Kogan Steam Mop ($59 from their online store) where it comes with the extra attachment nozzle that pumps out 108C steam water… It worked well but having to do it outside as it spitted the melt wax everywhere sticking to my tools, clothes, shoes …a bee even came to check out when the waxing smell flying in the air.

So a lesson being learnt here, I will do my final extraction in Feb or March then remove it for autumn stores and over winter… My bees are foraging throughout winter but I don’t think it is sufficiently for extra stores.


I think I’ll likely do the same going forward. I was hoping for winter honey- but I think the bees use it as they collect it and have enough room in the brood.

However if I have a super over 50% full I might consider leaving it. I have some steam cleaning machines but would be s but worried the steam might damage the plastic? From what I understand steam can be 400c? I’d even worry at 100c ?

I’m going to try soaking mine in warm water with mild detergent then high pressure water spray. Hopefully a prolonged soaking will soften the mold…


You could try diluted White King (sodium hypochlorite - it’s like a liquid chlorine) …if you dare. Deadly on mould. Rinse off well I guess. See link to cleaning/sterilisation etc below…


@Semaphore Soak the frames in NapiSan for about 4 hours then rinse with water and let them air dry, the mold and the mold spores will be gone.


Hi Busso, I am in Siesta Park near the beach - always very humid - and this Is my first winter with a flow hive. I have had lots of condensation issues and have just checked the flow frames and have quite a big mould problem. I wondered If you could send me a photo of your strategy to improve ventilation described in this post as I can’t picture it. I have taken off the flow frames and will try the napisan solution after freezing them for a few days. Di


Have just looked through my photos and I don’t have one useful to you.
I’ll do one tomorrow and hopefully post tomorrow night