Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

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Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Mini dehumidifier cost about $16 online.
Most buyers incorrectly use at open space bathroom or bedroom , fully saturated in 1-2 days.

Visible silica gel beads go from orange , purple grape , greenish , pinkish , transparent.
The internal heater element runs about 3/4 the length , no heat injury to fingers as it feels like full boil egg.

On the first heating recharge session it took 5 hours to fully dry it back to bright orange.
For cool down it took 3 hours in the covered steel pot for cool until room temp.

First problem was this freshly recharged device too strong for the dry cabinet.
Running into the low 30s % RH , had to open the cabinet door a few times per day to exchange humid air in.
Lower isn't better , too low into 20% or less RH can cause adhesive / lubricant / paint coating to detach.

Next recharge sessions I tried heating 2.5 hour and it was sufficient. Cool down times remain fixed at 3 hour.
Cycle between 50% to 40% RH measured at the lowest corner of dry cabinet. The cabinet's built-in digital hygrometer takes reading at top which is 7% lower.


Charging in unwanted steel pot to insulate the heat
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green to bright orange after 5 hours
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cool down horizontally in the pot for 3 hours , put a pot lid to stop air exchange
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The heating session consume about 22 watt for most of the duration and gradually lower to 18 watt at 5 hour.
No auto-cutoff function.
Electronic dry cabinet runs at 3 watt normally to hit 45% RH and 0.5 watt when lowest setting to only run the hygrometer display.
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At this scenario I tried to simulate a storage tub holding a 6 inch SCT OTA (17.5cm diameter) , used a dummy 20cm diameter cylinder.
My green plastic tub's internal size cannot fit 8" SCT. With 6" SCT there may be 2 to 4cm leftover in Length.
Tub's edges are terrible with open gaps on the top lid as it wasn't designed to be airtight seal.

After 2 run ending at approximately 10-11 days each, I received a bigger airtight tub with silicone o-ring seal to test 3rd time.

Conclusion : normal tub lid unsuitable with air gap leak , viable low cost drybox or plastic bag solution if airtight.

green tub with gap at lid edges
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airtight tub , listed as 80L with 63.5cm external , I measured 53cm internal length.
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28% RH climb to 51% over 65 days
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Did another test on a cracked tub that I repaired , brand new fresh dehumidifier + 5 hours heat recharge
It drop to less than 10% RH overnight. Verified with digital and analog hygrometer , drop 65 to 25% rh within first 3 hours.
This is too dry and potentially cause damage.
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Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

From S____e online shopping platform , price vary widely as different seller like to chop carrot on the odd desperate buyer.

For local option can buy from the JiJi brand , airtight - big - affordable mid $20s , but the seal ring is EVA foam not silicone. I got rid of many eva foam stuff in my home since they start to breakdown little particles when nearly 10yr old.
Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Updates after 5 months of usage of the airtight plastic tubs.
Works ok , bouncing between 40 to 50% RH. More usage = more recharge effort.

Bought the 40L Hercules tub from local brand Citylife. Available on shopping platform S____ and L_____
Not an advertisement post , I paid full price for my items.
Internal length 42cm x 31cm width. Bottom is flat without raised wheels so it get more support from the floor for heavier item.
Can stack ontop but cannot nest multiple within each other when unused storage. Vertical walls.
I recommend disassemble the silicone O-ring and wash everything with soapy water to remove any manufacturing oil.
Initially the O-ring tend to drop out , weeks after it's holding fine inside the groove.
4 side latches flip flop around block lid closure on single try , minor annoyance. 2 Bigger latches no issue.

Performance of this 40L tub is roughly the same as the above reviewed 80L tub , difference is November month much more rain than March-April.
Without opening the 40L tub , 25% climb to 40% RH takes 20 days.

Sold in 1 , 2 , 3 quantity. The 2pack is the most value. After stacking coupon and "app points" it's possible to get the Hercules 40L tub under $10 each.
I suggest skip the 26L smaller size unless you only use binoculars.

The $2 plastic hygrometer can be adjusted with a flat screwdriver at the rear opening. Take it out of a well referenced dry box and quickly adjust in 1 stroke. I received a few that were off by 15-25%.
Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Did a search just now and was surprised this xiaomi deerma mini dehumidifier have been discontinued by the handful of parallel import sellers at $15 price range. Only the official lazada channel is selling it at $21.

I bought the $6 bottle of orange silica gel (470grams net weight) to DIY a beanbag with a towel or sock as additional drying mass to reduce the heat drying frequency. Haven't done it yet , just future plans. Will attempt to heat the DIY beanbag by placing it ontop or wrap around the mini dehumidifier.
The mini dehumidifier weighs about 600+ grams and I estimate there is about 400-500grams of silica gel beads inside , the price difference is the convenience of heating element and casing as a finished product.
In mid 2024 I increased the heating duration from usual 4-5 hours to 7-9 hours and it works better as more residual moisture is expelled from the silica gel , increasing it's effectiveness and extend the heat recharge interval. Do note to not run heating device unattended as fire hazard.

For the above mentioned Hercules 40L tubs , I knew earlier the seller discontinued the 2 pack value combo and only sell 1 or 3 quantity , price quite steep compared to normal generic plastic tub without silicone seal.
There is a bigger 55L size currently at $5 more. https://s.lazada.sg/s.1gNnq?cc
Estimated internal length at 51-52cm , this may fit C8 sct or maksutov 6. Caution the plastic floor is thin , better to lay flat sheet support material for heavy items with small footprint if the tub is to be lifted.

Through my usage of the 40L version , I noticed improvement when additional weight or another tub is stacked ontop to press down on the silicone seal.
I have a scope tub with 2 mini dehumidifiers inside , stacked another accessory tub 4kg ontop , it went very slow from 25% RH to 40% at 100 days until I had to use the scope and interrupt the record. The default clamping power alone have air leakage.
With caution as the plastic and silicone may deform or damage under excessive weight.

For tubs without added weight ontop, I use plastic dust cover with elastic loop to extend the shield against indoor airflow hitting the lid and silicone seal.
It looks similar to shower cap and is a disposable product meant to cover aircon unit during renovation.

My dry cabinet finally broke down at the 11 year mark and fully transitioned to these silica gel products.
It was powered-on around 9 years throughout it's life. No light response on the internal module or hygrometer LCD screen , I assume it's the power supply failure. There was high pitch coil whine during the final year.

The $2 analog hygrometer have around 15% deviation between each other when I bought 3 pieces more. I placed them into the dry cabinet to take reference from 1 specific older hygrometer , after 4 tries at taking them out quickly to tune the rear slot with screwdriver I was able to get the 3 pieces to move in unison. There remains a 5% gap or responsiveness delay compared to the older hygrometer.

Found this replacement mini dehumidifier , around same price only 10% less weight. Select collection point for free shipping.
This same seller used to parallel import the xiaomi deerma design.
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Last edited by Hardwarezone on Sun Sep 29, 2024 2:34 pm, edited 1 time in total.
akdwivedi
Posts: 161
Joined: Sat May 06, 2017 1:01 am
Favourite scope: celestron C6

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by akdwivedi »

Thanks for sharing. This is very important in our weather conditions.

How do you heat silica gels, can we use microwave oven. I m thinking of getting silica gel and just heat them every month.
Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

akdwivedi wrote: Sun Sep 29, 2024 11:50 am Thanks for sharing. This is very important in our weather conditions.

How do you heat silica gels, can we use microwave oven. I m thinking of getting silica gel and just heat them every month.
I have not attempted to heat my raw silica gel beads yet. No experience.
My original plan to piggyback it ontop my heating mini dehumidifier cannot proceed as it have "do not cover vent" warning.
I will eventually (years later) heat it in unwanted electric water kettle with thermo knob at lowest or try those $9 small electric pot for cooking 1 pax instant noodle.
Silica gel beads can split open if the temperature stress is too rapid.
Pan-fry on low heat might be OK according to some online webpage.

The blue/orange type was more common until the bad press about the blue dye being carcinogenic and shouldn't be heated in kitchen microwaves or heating oven.
Green/orange dye type is common now and only about $1 increase per bottle. About carcinogen most online webpage are OK with green dye , some still call it unsafe.
Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

I changed to using this snack container for the 4 hour cooldown as it's better seal than my mismatch cooking pot and lid.
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For electronic dry cabinet it can recover back to 45% RH humidity in about 1 hour but using these big airtight tubs to recharge it takes 4to7 hour heat + 4 hour cooldown , this fluctuation of 12 hours at elevated humidity can be reduced by having another spare cartridge ready for swap. Plastic bag with stationary clips can keep it fresh inside another low quality container that isn't exactly airtight.
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Taobao china doing promotion from November to February , lots of free shipping coupon to claim at 12 midnight. It was 55cny off shipping and GST cost , this month reduced to 35cny off and not every day. I used sea shipping for all parcels and split the orders for maximum coupon.
The green color mini dehumidifier cost SGD $6.90 after all cost taxes coupons points , airtight case 5L size $1.90 each.
I searched entire Taobao , this Dapu mini dehumidifier have the most silica gel at 39cny list price , don't buy the smaller cheaper other designs at 20-65cny.
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5L case can fit this 22cm mini dehumidifier and 50mm Roof prism binoculars.
I did this as proof of concept that $10 cost can protect smaller binoculars.
For porro prism (svbony sv206 is fully multicoated at less that SGD $60) that are wider in size you need a bigger case that cost 20-25cny excluding shipping which is very sensitive to volume.
Although the manufacturer claims 6 years quality , I have similar silicone seal case for nearly 20 years it doesn't disintegrate.
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Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

From last post I realized this topic is too much text and too little photos , not suitable for beginner who want the final conclusion in a few minutes. Will try to focus on picture illustration.

Based on second-hand advertisement I think more than 50% of local beginners start with achromat refractor. Could be as high as 80-90%.
The problem is long tube are harder to store in airtight container or environment , while their relatively lower cost to apo refractor doesn't justify a $500-$1000 electronic dry cabinet to store it.

For my 102mm achromat with 660mm focal length , I had to remove the front dew shield and rear 2"to1.25" adapter to barely fit 55cm tube length diagonally in this 80L plastic airtight tub.
At the bottom right is Travelscope70mm with 400mm focal length.
None of the paper packaging for eyepieces went into the storage. Leave the dust caps off or loose fitting.

Do note the potential dry storage issues for 70mm 80mm F10 achromat.

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C5 sct compact tube in Cityiife Hercules 40L tub widely available in Singapore online platforms. You can get the 55L size to fit more accessories in.
I added an aluminium plate at the bottom as the plastic floor is quite thin in material , it does sag when lifted as SCT round tube have a small contact footprint.
Do note I bought the tub and 2 mini dehumidifiers with big coupon discounts , if all at full price $30 + 16 + 16 it would approach the price of electronic dry cabinet without the trouble of recharging every few weeks.
The cheaper electronic dry cabinets are more vertical than horizontal and require the scope to be sitting vertical with weight on it's visualback , DIY steel wire similar to clotheshanger to safety belt secure it into corner of dry cabinet.
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Hardwarezone
Posts: 393
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Fungus Prevention : Low Cost Dry Storage With Mini Dehumidifier

Post by Hardwarezone »

Common issue in Singapore. Preventable.

Photos were before cleaning.
Note the SCT in above photo is stored separately from other accessories as the rear section after the mirror cannot be accessed without extensive disassembly. I was only able to heat up the rear to 40s when I was sterilizing the mirror and interior with sunlight before cleaning, 40s degree celcius may not be enough to kill the spores.
For cheaper achromat refractors they are easier to disassemble and wash entirely after grease removal from focuser , therefore cleared to join the common storage. Amateur disassembly may affect the alignment of lens which reduce the highest capable magnification compared to fresh from factory.
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