PlanetCatfish.com

Hello all,

Quick question: Wouldn't the water from a home dehumidifier be better to use in an aquarium than tap water?

Thanks for chiming in!

I was wondering the same thing, there's no shortage of rain this year here so mine fills up once a day. I only know it's wonderful to wash your hair with, lots of bubbles!

The water extracted from the air is very soft, in that capacity compareble to RO water

BUT how does such a dehumidifier work? If it uses any chemicals, the water is not usable. If the water is extracted from the air by energy alone, it might be usable, but indoor environments are said to be not that pure

However, would it not be much easier not to use this water, but collect rainwater? At least the indoor addition to the eventual pollution has not taken place, and presumably the amount of water will be much more

yeah, and some dehumidifiers have copper pipes in there, and in that case its best not to use that water. then there is the problem of other stuff being sucked up like aerosol sprays, fly sprays etc. its too much of a risk so i don't use it, although i usually have to remove 10- 15L of water from the dehumidifier every day!

Not to mention that the common reason for having a dehumidifier is that there is some sort of humidity problem - which usually means that there is mold in the vicinity, which in turn means that the air will have spores of mold in them. Not necessarily great for the fish, I'd say.

--
Mats

I have used dehumidifier water to soften the water in my tank, without any apparent problem. I usually do not use more than about one third dehumidifier water.

I have read the theoretical criticisms of using this water, both in this thread and on other websites, namely that the water touches copper coils and therefore has copper in it and that it also has pollutants from the air. I'm skeptical of these criticisms.

I doubt that much copper gets into the water, or else the coils would deteriorate rapidly, which is not my experience. In any event, I use Prime as my water conditioner, which is supposed to detoxify metals.

As far as the airborne pollutants go, I would be surprised if there is a significant amount of pollutants in the water, but I certainly don't have any way to test this.

Obviously, there are a fair amount of pollutants in tap water. Think of the articles you read about pharmaceuticals and hormones in our tap water. Certainly the water from the dehumidifier does not have those.

I'm not trying to start an argument here, but just want to point out that my experience does not indicate any problems with using this water.

MatsP:

Not to mention that the common reason for having a dehumidifier is that there is some sort of humidity problem - which usually means that there is mold in the vicinity, which in turn means that the air will have spores of mold in them. Not necessarily great for the fish, I'd say.

That would make sense in most cases but in my case, there's definitely no mold issues since our whole basement has recently been torn apart and the signs of moisture were absent. A certified house inspector also gave it the once over. The dehumidifier issue here is that we live on a massive lake and if I put my dehumidifier on my boiling hot deck, it would still fill up in one day. Almost every house in this area has a dehumidifier built into the furnace too. All the new houses do as well, no mold issues there.

Sunny and clear at the moment and a quick check of the local weather says "humidity 73%" If you have skin issues, it's a nice place to be, if you have lung issues, you don't want to live here!

Anyways, good info. I'll keep using mine for laundry and hairwashing just to be on the safe side since I have a rainbarrel now and snow in the winter. This may not be an option for people who have dehumidifiers but live in apartments or condos. My dehumidifier has a HEPA filter but I've never checked the coils.

phoenix44 wrote:

yeah, and some dehumidifiers have copper pipes in there, and in that case its best not to use that water. then there is the problem of other stuff being sucked up like aerosol sprays, fly sprays etc. its too much of a risk so i don't use it, although i usually have to remove 10- 15L of water from the dehumidifier every day!

Good point. I never use any aerosols anymore anyway. Scary stuff to have sucked up by an airpump or settle on tankwater. Scary stuff to have sucked up by me! Flyswatters give a better challenge.

You should add bleach to your dehumidifier reservoir as a a precaution against Legionnaire's disease. In which case you definitely shouldn't then add the water to your fish tank.

You should add bleach to your dehumidifier reservoir as a a precaution against Legionnaire's disease. In which case you definitely shouldn't then add the water to your fish tank.

I think that may be for sitting water like in a humidifier, or any water reservoir, most DE-humidifiers here are emptied daily. Wonder what 'bugs' my HEPA fliter actually traps from the air?
Good info to keep in mind anyways, here's a link I found about that:
http://www.jshumidifiers.com/company/SE ... etails.htm

MChambers wrote:I have read the theoretical criticisms of using this water, both in this thread and on other websites, namely that the water touches copper coils and therefore has copper in it and that it also has pollutants from the air. I'm skeptical of these criticisms.

I'm more than skeptical of that criticism, I think it's outright wrong.
What do you think all the pressurized plumbing in your house is made from? Let's say it all together....copper!

I've thought about collecting rainwater, but here's my problem with that:
The easiest way I have available to collect any significant amount of rainwater is from the downspouts on my house. Where I live, we have a lot of birds (and subsequent pooping) and seeds, leaves and sticks that end up in the gutters. I know that stuff and byproducts from its decomposition would be in any collected rainwater.

My tap water is very hard and the city adds fluoride and ammonia to their system. I think I'm going to continue supplementing my water changes with dehumidifier water. So far I can only collect about half what I need for a typical scheduled water change anyway.

I know a whole bunch of members of the American Killiefish Society that use their dehumidifier water with their precious Killies.
It has been discussed on http://www.killietalk.org at length many times and the consensus is if you have it the use it.
I daresay that their are many Killiefish that are much more sensitive to detrimental substances in their water than the majority of catfish. Just take care that you use it mixed with some tap water or RO Right as you would with any source of essentially pure water.

Fred T. Washington wrote:What do you think all the pressurized plumbing in your house is made from? Let's say it all together....copper!

This is true, but chemistry is sometimes a funny dicipline

I studied chemistry, with a second in biology. I mistreated fish (Oreochromis mossambicus) with copper and cadmiumsalts, to study their reactions

As the university was housed in quite an old building (study in 1992, build in 1957, but intended to last for 10, max 15 years) there was a problem with copper piping. On an early monday morning the copper content in the standing water could raise to 60 pp, while normally it sank to 10 ppm on tuesday, and remained on that level

Obviously this is not something one can work with, so the experiments were done with artificial water: start witrh demineralized water, and add calcium, magnesium salts to reconstitute the original water - or the water the fish would prefer

The fish in this wate grew very slowly compared to those (siblings, or close to siblings, the breeding stock were siblings) in normal water. but, on a hormonal level, one could see quite a fierce adaptation to the 10 ppm copper water

Thus, going back to fishkeeping, these fishes did obviously better with some copper, because they were able to adapt to copper. Catfish are - generally speaking - rather sensitive towards copper

From a purely chemical point of view, I think I should add another observation: the purer water is, the more corrosive it is. Water wherein nothing isdissolved (such as the water a dehumidifier produces) is much more agressive than the water we all get from the tap. Therefore the 10 ppm copper content I mentioned above, with our local tapwater (I studied in Nijmegen, where I happen lo live again) can not be seen as an example for the coppercontent the dehumidifier produces

Personally I would be very careful with this water

I have to agree with Bas in principle. But I will also point out that my RO system has copper pipes in it - one 15mm x 12 cm piece to connect the base of the two containers, and a 22mm x ~30cm piece where it goes to the pump. I presume that if I have 10 ppm copper in the water, it would show up noticably on the TDS meter, compared to the RO water straight from the RO unit itself.

Or did you mean ppb? 10 ppb is WAY under the lowest legal drinking limit that I've found - in the US (first place I found data for), legal limits are around 0.2 to 1.3 ppm.

--
Mats

Fred T. Washington wrote:I've thought about collecting rainwater, but here's my problem with that:
The easiest way I have available to collect any significant amount of rainwater is from the downspouts on my house. Where I live, we have a lot of birds (and subsequent pooping) and seeds, leaves and sticks that end up in the gutters. I know that stuff and byproducts from its decomposition would be in any collected rainwater.

Yes, at the least I think you would want to boil the rainwater before you use it. Some people also have theorized that if you have asphalt shingles you will have bad chemicals in the rainwater. I'm skeptical of that, given how much rain my roof has seen over the years and how little contact time there is between water and the shingles.

Anyway, this is a very constructive and thoughtful thread.

MatsP wrote:I have to agree with Bas in principle. But I will also point out that my RO system has copper pipes in it - one 15mm x 12 cm piece to connect the base of the two containers, and a 22mm x ~30cm piece where it goes to the pump. I presume that if I have 10 ppm copper in the water, it would show up noticably on the TDS meter, compared to the RO water straight from the RO unit itself.

Or did you mean ppb? 10 ppb is WAY under the lowest legal drinking limit that I've found - in the US (first place I found data for), legal limits are around 0.2 to 1.3 ppm.

--
Mats

I intended ppm, not ppb.

Purely based on memory, a conductivity of 0,1 ms/cm could be the result of such a pollution - not much, but noticable

0.1 ms/cm is about 130-200 ppm TDS [depending on whose scale you use].

--
Mats

Water from a dehumidifier will be toxic if there is cigarette smoke in the room or fumes from paint or other chemicals.The toxicity can be quite significant, and I know of two separate occasions when it has resulted in large number of fish deaths. In both occasions cigarette smoke was the corporate.

No smokers in this house. No fresh paint, no bug spray or mold issues either. I thought this would be a fairly simple question, boy was I wrong! Maybe this could be a good excuse to get another tank (or two or three!) and do a study on dehumidifier water.

Fred T. Washington wrote:No smokers in this house. No fresh paint, no bug spray or mold issues either. I thought this would be a fairly simple question, boy was I wrong! Maybe this could be a good excuse to get another tank (or two or three!) and do a study on dehumidifier water.

no kidding! I researched this about a year ago and did not find much in the way of definitive answers. This thread is the best I have seen on the topic, on any website.

EMERGENCY! EMERGENCY! EMERGENCY!
On a whim I thought it would be a good idea to test my reservoir of dehumidifier water and these are the results:

pH less than 6.0 and Ammonia between 4.0 and 8.0 ppm!

I just about crapped my pants! Since my Q tank received a greater percentage of the dehumidifier water than my main tank I started the series of tests on it first. Results:

pH less than 6.0, ammonia 2.0 ppm and nitrate 0 ppm

So not only is my pH whacked, my cycle does not even appear to have started!
Main tank results:

pH 6.0, ammonia .5 ppm and nitrate 10 ppm.

I removed 25% Q tank water and replaced with water from my main tank in hopes of getting the nitrogen cycle jump started. My seeding attempt to start it has obviously failed. I replaced the water in the main tank with treated (ammo lock & stress zyme) tap water. I expect I have some buffering issues with this tank which I will investigate and remedy tomorrow morning.

I plan on daily water changes in the Q tank until the test levels get closer to normal.

After my near panic abated I tested the water straight out of the tap:

pH 7.6, ammonia 1.0 Numbers I can live with (although I'd like to see the pH lower)

So here is my official position on dehumidifier water:
I WILL NEVER USE IT IN ANY TANK EVER AGAIN!

Should you choose to use it, please test it first. You could save yourself a stressful evening.

The low pH for the dehumidifier water comes from carbondioxide - also known as carbonacid. It is the stuff we breath out, and therefore quite normal. Destilled water does niot have any pH buffering capacity, and therefore the slightest addition of acid will drop the pH. However in the Q tank some buffering capacity is to be expected

What surprises me is the ammonia. Amonia does dissolve very good in water, so if a little is in the air, quite a bit will be found in the dehumidifier water, but where does this come from? Do you happen to life in an agricultural area, where the farmers have recently fertilized their fields - with dung ??

@ starting a nitrate cycle, the bacteria doing this mostly cling to surfaces. assuming your main tank does have a functioning one, it would be better to put some rocks, and sand, from this tank into the Q tank than the water - thisway you transport more bacteria.

However, I read some ammonia is in the main tank too - did you allow the nitrate cycle to have started, or did you measure the water quite soon - within an hour or so?

In English it's "Carbonic acid".

--
Mats

thanks. I should have known that

I am very curious as to how you could get ammonia in your dehumidifier water. Interesting, folks have suggested all sorts of problems with dehumidifier water, but nobody suggested ammonia. I will test mine and report back.

Yes, it is a bit of conumdrum. As Bas say, Ammonia is highly hydrofilic. On of the experiments in chemistry is to have a bottle with a bit of ammonia gas in it, a long pipe with a valve into the bottle, and open the valve with the pipe under water. Because ammonia draws in so much water, you will get a fountain inside the bottle.

So ammonia available in the air will seek out water. But it's not common to have ammonia in the air!

--
Mats

I wish I knew the source for the ammonia in my dehumidifier water. The reservoir looks clean. I don't smell it in the air and I live in residential suburbia miles from the nearest farm.

I wonder if one of the kids did something. No way of ever finding that out without thumb screws.

My dehumidifier is located right next to the washing machine and dryer. Do you think that might explain the ammonia? One of the kids does wet the bed.

Another possible explanation I just learned from my girlfriend is that our dog sometimes pees on the concrete floor next to the dehumidifier. Seriously? Am I the only person that can take the dog out?

When I originally tried to seed my Q tank I took some of the white filter media thingies out of my main tank canister filter and put them in the Q tank filter. I thought I was doing it right...

Maybe the ammonia was a fluke thing for me but regardless, I'm done with it. I lucked out this time and all my little fishies are doing fine but who's to say it can't happen again. Better luck to anyone else using dehumidifier water. Please be sure to do your testing BEFORE you use any.

Hey Fred, ever here of Monticello IA? That's where I used to live before I moved to "The Frozen Tundra".

Anyway, I'm going to put in my 2 cents worth here. I've seen this topic debated over and over again.
Many say, "Look out! Dehumidifier water is soooo bad" while others have mixed opinions with only
a few people stating that dehumidifier water is safe, besides the very few who actually use the stuff.
Well I'm one of the few people that actually uses dehumidifier water and with a limited few others
that I know who use it, all I can say is in my experience, dehumidifier water is completely safe at least
for the species of plecos that I spawn. My tap water has a TDS of around 340 ppm and with water
changes using 40-50% dehumidifier water, I'm able to keep most of my tanks around 180-210 ppm.
I still plan on using R/O water, but with the current slow economy and my local utility company
raising our water rates by 31%, I still can't swing the cost (yet). I myself spawn mostly Ancistrus
species with some recent success in spawning Tatia intermedia and Nomorhamphus ebrardtii.
I keep a limited number of Hypancistrus but one of my breeder contacts spawns not only several
species of Hypancistrus including L046, but also L183, L088, L007, and even L255 using dehumidifier
water. I do use Kordon's NovAqua to treat all my water and I think the other guy uses Prime, but the
moral of the story is that in our situation, dehumidifier water has produced fantastic results so I'm
not sure if I would listen to all the "hype" about dehumidifier water being so terrible. On a final note,
I will agree that there is a possibility of trace amounts of copper so maybe very delicate shrimp or
fish species that are extremely sensitive to copper may be at risk. But that's the reason I treat all my
water for heavy metals and I also have to think about all the fish medications that people use everyday
containing copper. I'd be glad to provide information reguarding how I use dehumidifier water so
just PM me if you would like a more detailed explanation. BTW I just had some wild Ancistrus spawn
a few days ago that I grew out from around 1.5" to breeder size, so can dehumidifier water be that bad?
Or was it the oak cave I added to the tank 3 days prior to the spawn? I guess I'll never know. LOL!

Wee, whether human or dog, will convert to ammonia once released from the bladder via various bacteria.

--
Mats

Fred T. Washington wrote:EMERGENCY! EMERGENCY! EMERGENCY!
On a whim I thought it would be a good idea to test my reservoir of dehumidifier water and these are the results:

pH less than 6.0 and Ammonia between 4.0 and 8.0 ppm!

Interestingly, I just tested my dehumifidier water and found ammonia, about 3 mg/l. No, there is no wee in my dehumidifier, and I'm pretty sure my kids didn't do anything unusual. So I won't be mixing this in my tank again. Fred, thanks for giving us the test results.

I'm still mystified by this, but it really doesn't matter what the cause is.

Please remember there are two types of ammonia (NH4+ and NH3) and only the non-iodized form
(NH3) is toxic, besides the percentage of NH3 to total ammonia is dependant upon both pH and temperature. OK so 6 mg/l = 6 ppm total ammonia, then at 80° F and a pH of 7.4 (in my aquarium)
that would reflect a value of about .1 ppm (toxic) NH3 so wouldn't that be enough to kill all my fish?
And since I've been using dehumidifier water for the last 18 months straight, I have not had any
unexplained deaths with the only deaths being clearly parasite related due directly to contamination
from incoming wild fish. I also know that some test kits give false readings and certain kits are
not compatible with certain additives.

I can't find my chemical ammonia test kit but I will keep looking and test my dehumidifier water
directly. I suppose it's possible that some ammonia is present, but since I mix tap with DH water,
treat it with NovAqua (which also removes ammonia), then aerate the mix for several hours
(sometimes overnight) before actually performing a water change, obviously it's working well for me.
If one takes the parameters of pure DH water itself, lets say pH 6.0 and at room temperature of 68° F,
then the level of toxic NH3 would be around .008 ppm and this level would be completely safe with
the danger point being .03 ppm NH3. I think any well cycled aquarium would absorb this small
amount of ammonia with no problem and possibly even help to keep bacteria counts at a healthy level.


http://www.dataguru.org/misc/aquarium/AmmoniaTox.html

http://www.thekrib.com/Chemistry/ammonia-toxicity.html