Tank ventilation, or drilling holes in glass?

whitecat8(z4 MN)September 4, 2009

Thinking of ways to increase air circulation in the 36"x18"x16.5" glass terrarium. The fan that was blowing air over the open top died, plus everything needs spraying about 3 times a day. Not gonna happen.

The last time I looked at camping tents, new models had ventilation holes @ the bottom (screened to keep bugs out), w/ screened openings in the top. Lovely air flow.

The Exo Terra has the slits near the bottom of the front-opening doors and the screened top - air flow.

The Exo Terra is too pricey, so I'm looking for "natural" ventilation for the tank. There are two brooder lights above it w/ 23W CFLs in them. The screened top has been off, but it can go on, if it'd help, but I'm concerned about reduction in the amount of light. Stronger CFLs are an option.

Is it possible/desirable to drill holes in glass? I'm guessing this isn't tempered. Could a specialty place do it? Holes might be about 3" from the bottom of the tank, below any of the plants.

If holes in the glass aren't feasible, how would it be to

- put a glass panel on the top that has open space at both ends for air flow. Kevin, your fungus problem is in the back of my mind all the time.

- use a couple of small clip-on fans or computer fans inside the tank to move air, hopefully exchanging air via the open spaces at the top, if the fans are positioned correctly

- increase humidity via ultrasonic humidifier w/ tubing

Or maybe do these in conjunction w/ holes in the glass.

Your wisdom would be greatly appreciated. Whitecat8

Here is a link that might be useful: Exo Terra tank w/ ventilation

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I wouldnt rely on "natural ventilation. The tiny pressure changes from the room and your tank are not enough to create a great deal of ventilation that orchids want. Especially if they are being misted multiple times a day. Get a computer fan at least. I had a grow case setup where I had a bathroom fan (what would be in the roof or wall) inside of a tank of water and had a hose going off the end into the case for ventilation humidity needs.

    Bookmark   September 4, 2009 at 8:53PM
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quinnfyre(z7 PA)

My case is 24x12x12. It has a lid on top which is not airtight, but the gaps are small. All that I am using is a small computer fan. It seems to do the job quite nicely. I only water once a day or once every other day. I'm actually not a big fan of the ventilation slits in the ExoTerras. It makes keeping humidity up above 60% very difficult, and I have covered the screen tops completely. What I'm worried about is that it only goes up to about 60% while the humidity in the room runs about 50%. What's going to happen in the winter when the humidity in the room goes down to about 15%? I guess I'll find out.

    Bookmark   September 4, 2009 at 9:04PM
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xmpraedicta(3b Saskatoon)


What has worked for me for a few months now is similar to Quinnfyre. I have an open top tank (same dimension as yours) and I have two salvaged windows (the kind that slide on a track) just sitting on top, covering the top, but with a gap in between for air. Inside are two computer fans...the moving air inside ends up pushing some air out of the gap and ventilation happens - no mold or anything.

I mist once a day in the mornings, humidity is up to 99%, drops to about 45% by evening. Plants don't mind (growing all aerangis species and some bare root plants for rehab) but I'm thinking I need to put my automatic system back up so I can get a watering in during the day when I'm gone (things are bone dry by the end of the day)

In regards to misters, they are a bit finicky. Some people can set them up beautifully, but personally I have had some problems getting good mist distribution - ie I would get tons of water and condensation in the direct path of the mist, resulting in a sopping mess, and other places would barely get a layer of dew. I think Mr.B's idea of using multiple tubes to siphon the mist evenly everywhere is a good idea.

Also, be careful about ultrasonic misters - ultrasonic humidifier units come with a built in fan that projects the mist up nicely in a stream, which you can redirect with tubing. However, if you just buy the ultrasonic misting disk unit (most popular source is mainlandmart) the mist just sits in the bottom of the water reservoire, making it useless. What's worse, the darn thing splashes water everywhere!

Holes in glass can be drilled with a diamond drill bit (5-15 dollars), an electric drill and a lot of patience. If you have a hand husband around, that could definitely be an option. If you google 'drilling hole in glass' you'll find lots of step-by-steps. That said, not sure what a hole would accomplish unless you plan on sticking something into it.

    Bookmark   September 4, 2009 at 9:37PM
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xmpraedicta(3b Saskatoon)

*handy husband...and obviously I'm not suggesting that this is man's work!! (just covering my bases here...)

    Bookmark   September 4, 2009 at 9:40PM
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whitecat8(z4 MN)

Thanks much. See, this is why y'all are terrific - my brain hadn't gotten to the part about quality of incoming air. Quinn, my long-distance love affair w/ the Exo Terra may have just ended.

Calvin, you're a little safe on the hand husband part b/c you have sooo much info that I'm not a hand kinda gal. :) Although you're in trouble again b/c DH isn't, either, and my female orchid buddy is super hand-y.

MB mentioned the Holmes brand of ultrasonic mister here, and our Targets carry them in the fall.

Quinn & Calvin, did you wire the computer fans yourselves?

Sake, I'm not quite following your description "had a hose going off the end (of the fan?) into the case for ventilation humidity needs." Can you say more?

A work in progress...

Thanks again, WC8

    Bookmark   September 5, 2009 at 2:34AM
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quinnfyre(z7 PA)

Well, I'll let you know how it goes this winter. If I get my finances in order before then, I will complete my larger ExoTerra terrarium project. If not, I'll still have some info cuz I am currently using the large one for hoya starts and rehabbing problem phals. Oh, and the newly mounted Aerangis modesta seedling is in there too. The larger ExoTerra is doing much better at staying around 65%, going up to about 80% when freshly watered (got a Hydroton tray in there for extra humidity.) The smaller ExoTerra however seems to stay around 60% no matter what I do. It does have the least fancy hygrometer in there, but I thought it was pretty accurate. I might have to recheck it one of these days.

I wired one of my computer fans myself. One I received already wired. But best of all, I just got a couple new fans, which needed no wiring whatsoever and came with an AC adapter. Plug the fan to the adapter, and then plug the whole thing into an outlet, and you're good to go!

    Bookmark   September 5, 2009 at 2:46AM
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ttkidd(Toronto ON)

If you plan on doing in-situ drilling on your tank I would advise holding a piece of plywood behind the glass while you're doing it. With an unsupported sheet of glass, it is very easy to crack it, even with proper use of the diamond drill bit. Don't forget to keep the bit wet too...the bit won't last very long if it heats up too much. I have spent a number of hours now drilling holes in glass vases for my s/h plants. It's a tedious process and can take a while to drill each hole.

Which ventilation slits are you talking about on the Exo-terra? I just got mine on Sunday (18"x18"x24"), and while it does have a screen top I see no ventilation slits near the doors.


    Bookmark   September 8, 2009 at 12:46PM
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quinnfyre(z7 PA)

You see that black strip just underneath the glass doors? All the holes in it provide ventilation. The ventilation holes go up at an angle, so it's not immediately obvious. If you look at it from the inside, the top of the strip has little slits. That's where the ventilation holes feed to. If you need a clearer view of how they work, use a lit stick of incense (or something that produces smoke) and hold it near the front holes. You'll see the smoke appear inside through the slits. I did this to check the pattern of airflow in my tank once I placed the fan in it.

    Bookmark   September 8, 2009 at 4:13PM
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ttkidd(Toronto ON)

Ah...now I see. I thought the fog leaking out the front was because the doors weren't airtight. Thanks :) Even with the holes I'm able to keep the humidity in the mid to high 90s though. The hygrometer that comes with the tank is crap....it consistently measures 60 while my own swings quite nicely depending on whether or not the doors are open, or if my fogger is on.

    Bookmark   September 8, 2009 at 8:11PM
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whitecat8(z4 MN)

Quinn, where did you get your computer fan that was wired already? And where did you get the 2 that came w/ an AC adapter? Those sound like my "unhand" style.

How are you attaching the fans to the tank?

About the only ones I'm finding are 6" clip-on fans. Maybe pulling out a cannon to shoot a mosquito.

On Sat., I got 2 glass panels to go over the top and leave breathing room. Gotta go back and get another panel - maybe too much breathing room.

I'm gonna get the MistKing stuff. If it lasts 4 years, it'll be less expensive than replacing humidifiers so far. Plus, there will be less potential that user learning curve/error will result in puddles in the wall-to-wall carpeting.

Ttkidd, no chance of me trying to drill holes in the glass. Fans sound like a better solution than pulling in dry, cooler air via ventilation holes. Thanks for the suggestions, though.

Getting there...

    Bookmark   September 9, 2009 at 5:24AM
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westoh Z6


I'm the same as Q, I use 2 computer fans (80mm I think) to cool my 55 gal tank. Beings it is an aquarium, I was able to purchase 2 fitted 'lids' from the petstore. The lids are 1/2 glass and 1/2 plastic and can lift-up from the plastic side. I have 2-65 watt long CFL's in a 4' fixure sitting over the glass portions.

I originally super glued my fans to the under-side of the 'lids'. I had one of the fans fail after 2 years and had to replace it, instead of super gluing this one, I used the metal duct tape that you see used on ductwork joints and furnaces to hold the fan. It's been about 4 months and so far it's holding. I like the tape solution better than the super glue for ease of removal reasons.

I use an AC adapter to power the 2 fans. The adapter is on the same time cycle as the lights. Here is a link to an AC power adapter for computer fans. http://www.cablesonline.com/mo4inpotoacp.html

Be sure to buy fans or wiring with MOLEX/4-pin connectors and get a MOLEX splitter if you plan on using 2 fans. There are also many fans on the site if you need to acquire those. I have access to many computer fans so all I needed was an adapter. I can tell you to look for the quietest fans you can find/afford, the noise is a bit distrubing if you use the louder fans. Adapter, connecters, splitters and fans should cost less than $40 total.

I manually mist 1-3 times daily also, but that becomes a pain so I'm looking to automate the process. I'm thinking one of those lizard misters, but haven't spent too much time investigating the solution.

As far as humidity, I placed about 1" of Ray's rocks on the bottom, put a fitted piece of egg-crate over that and then put a piece of green aquarium floor cover over that. Looks pretty good and about once a week I pour @ 1 quart of water in the bottom to keep things humid. My tank usually runs about 20-30% higher humidity than the room.



    Bookmark   September 9, 2009 at 7:02AM
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hi, i have been reading this thread with interest.
Bob, what are Ray's rocks?

    Bookmark   September 9, 2009 at 8:39AM
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For fans there are a few prewired ones out there. Coralife makes a cooling fan for their cfl fixtures-4" computer fan style. I use one in my 10 gal-works great. Black Jungle sells a similar one now-would be perfect for exoterras. Both are prewired to an adapter just plug in and both are around $20 i think.

    Bookmark   September 9, 2009 at 10:11AM
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quinnfyre(z7 PA)

The already wired fan I bought from someone who didn't need it anymore. I think it is a 50mm. The two that came with an AC adapter I got from the place I linked below. I got that 60 mm fan, as well as an 80 mm fan, the Vantec stealth, which is definitely quieter than the other one I got. It doesn't come with the fan grill as pictured (it says that in the description). It's a larger fan, but I'm using it for the larger case.

I attached the already wired fan with those small Command adhesive hooks that are clear, and some wire. It sits across the top corner, pointed slightly downward. The others are just hanging at the moment. I haven't decided final placement, but I wanted to get something in there quickly.

Here is a link that might be useful: 60 mm fan

    Bookmark   September 9, 2009 at 1:41PM
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westoh Z6


Ray's rocks are the PrimeAgra pellets/balls used in S/H culture. I happened to have a few laying around at the time so I used them. You could use gravel. It's just something to increase surface area to generate a little more humidity.



    Bookmark   September 10, 2009 at 6:59AM
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hello, Bob, thank for the info.

    Bookmark   September 10, 2009 at 3:05PM
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whitecat8(z4 MN)

Thanks for the sources, guys. All I was finding were 4" clip-on fans, which sounded like monsters.

    Bookmark   September 11, 2009 at 12:02AM
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garyfla_gw(10 Florida)

I tore down the 150 gallon aquaium and was going to drill some holes in the bottom for drainage but there was a tag that said "Tempered glass do not drill" If that tag had not been there I would probably have gone ahead and tried to drill. What happens, shatters??
Is there a way to tell tempered glass without a tag??

    Bookmark   September 14, 2009 at 5:49AM
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whitecat8(z4 MN)

From WiseGeek.com: "Tempered glass breaks in a unique way. If any part of the glass fails, the entire panel shatters at once. This distinguishes it from normal glass, which might experience a small crack or localized breakage from an isolated impact.

"Tempered glass might also fail long after the event that caused the failure. Stresses continue to play until the defect erupts, triggering breakage of the entire panel."

No tag on glass and maybe no almost-invisible printing on glass and the manufacturer went out of business - I'd probably assume it was tempered. Otherwise, I'd call mfr. or Google product.

Here is a link that might be useful: WiseGeek.com - tempered glass

    Bookmark   September 14, 2009 at 7:20AM
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dellis326 (Danny)

Hi all, I'm new here, This thread caught my eye because I work with glass for a living.

If the glass is not tagged there is no way to know if it is tempered but it is a safe bet to assume any aquarium twenty gallons and up, that is made of glass 1/4 inch or less is tempered.

This statement; >
Can apply to any glass that becomes scratched, tempered or not. TG will more likly break and should break into small, safer pieces then untempered when trying to cut through it. Tempered is not stronger then untempered glass, it's just more impact resistant and when it breaks it should fall into small cube-ish pieces rather than sharp shards

If the tempered glass is thinner than 1/4 the safest way to cut into it is to sandblast it which not many places that blast know how to work with glass but there are alot of hobbiest and small independant glass etchers around that might be able to it. It still might break though, you just have no way of knowing.

With diamond wheels the main thing is to keep enough water flowing over the work piece to keep the glass from over heating which will expand the glass unevenly and crack it. Many diamond cutters are fine without water, you'll just ruin the glass without it or at best, clog the cutter so it won't cut anymore (which also causes more heat).

Hope that helps, It's nice not being a lurker for once

    Bookmark   September 14, 2009 at 9:39AM
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Thank you, Danny!


    Bookmark   September 14, 2009 at 2:14PM
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garyfla_gw(10 Florida)

I thank you also!! Guess I'll just have to figure an "automatic" siphon.lol Interestingly not only has nothing croaked in the tank they are flourishing lol
Still can't believe going underwater for a couple of hours can be good for them. One particular surpise has been the selaginells, jewel orchids. While they grow well
in an ordinary method they have exploded in the tank. Another is cutting of Coleus.
Another interesting aspect is that due to direct sunlight the tank never falls below 80 degrees.
Guess there's always more to learn. Should get some more lessons with the coming winter lol Thanks again gary

    Bookmark   September 15, 2009 at 5:30AM
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ttkidd(Toronto ON)

garyfla - Interesting about the direct sunlight. I've been told on another forum that I really shouldn't be putting my tank into direct sunlight, but my plants seem to love it so far. With my fogger going temperatures at the top of the tank seem to be maxing out at just over 100F. Root growth exploded as soon as I started moving my plants in there.


    Bookmark   September 15, 2009 at 9:28AM
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whitecat8(z4 MN)

Danny, thanks for the good info. Y'all are giving me much food for thought.

    Bookmark   September 15, 2009 at 12:20PM
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garyfla_gw(10 Florida)

I was always told that about aquariums also lol "Direct sunlight will cause a mass outbreak of algae" The reality was just the opposite. best planted aquarium I ever had except for the constant pruning.. I used the aquarium as a reservoir for the waterfall and as a supplemental heat source during winter. Can't think of anything else to use a 6x2x2 foot leaky glass box for except a terrarium.lol
Have put cuttings in it from 15 different species of tropical plants but have not figured out a workable lid
It has filled completely several times ,partially about every other day lol. I would have just removed the silicone to make it leak more but makes a mudhole in the shadehouse . I have a built in siphon which drains into the lily pool but requires I start the siphon each time .
I was planning on a complete failure as a terrarium due to the water the heat and the direct sunlight .
Go figure lol. Only thing that has declined are some epidendrum orchids but even they are hanging on.
I can see already that I'm going to be doing a LOT of pruning but will be fun to experiment with different species.
Maybe we shouldn't believe evrything we read?? lol gary

    Bookmark   September 16, 2009 at 5:51AM
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