Public Service Announcement: Evaporation and Mold

[SoloGarth]

So I wanted to make sure people are aware of this as it has caused a very major problem for me. Tank evaporation and black mold.

My 120 has been up and running for about 5 years now. I have always monitored humidity in my home to ensure that things were never too humid as I was concerned about the problems that might present. Generally humidity never rises above 45% in my house. However my system evaporates 1 - 2 gallons per day I would estimate. So I was always unsure of where that water was going. The tank is in a large open space with 15' ceilings so I had kind of figured that the water was just dissipating into the space. After all, if humidity never rose above 45% and was frequently much lower it was fine. Here I was very wrong.

I have been having problems the last few years with my roof "leaking". I had thought this was from ice damns forming on the roof. So I have had the roof ice and water shielded and checked a few times. This year my father mentioned that the "leak" might actually be melting ice that had condensed on the bottom of the roof. So we took a look at the inside of the plywood. Totally soaked and dripping across nearly the entire roof. And to make it worse all the plywood is totally black with mold.

So here is what happens. During the cold months the moisture laden air pass through the ceiling and through the insulation where it hits the underside of the frozen plywood. There the moisture instantly freezes and builds up an ice layer on the plywood. When the temperature rises the ice melts and drips back into the house which appears to be a leak in the roof.

The temporary fix is running 2 70pint/day dehumidifiers 24/7 and sealing the affected areas off as much as possible. The real fix is that this spring I am going to have the entire roof replaced and insulated with closed cell spray insulation to provide an actual vapor barrier (something my house was apparently built without). It is sure to be expensive.

Hope that no one else is having these problems and I would advise taking a look to make sure nothing similar is happening in your home. Particularly those people with large systems.

 

[outy]

How is adding 140 pints of water into the air helping anything?


I have never heard of a tank evaporating that much to cause condensation above your ceiling.


You have some other issue going on is my bet. Usually above the ceiling is vented so moisture does not accumulate.

 

[SoloGarth]

How is adding 140 pints of water into the air helping anything?





I have never heard of a tank evaporating that much to cause condensation above your ceiling.





You have some other issue going on is my bet. Usually above the ceiling is vented so moisture does not accumulate.

That was an auto correct problem. Dehumidifier not humidifier.

And what other type of issue?

 

[SoloGarth]

Also just because you haven't heard of it doesn't mean it doesn't happen. There are a lot of factors such as length of time over which the system is running, outside temp, method of insulating the roof ect. Also I have a feeling that it is likely more people have similar problems and don't know it. It is not usual for people to look on the inside of the ceiling and walls and if you don't you won't know. My tank isn't even that large at ~150 gallons total volume. The evaporated moisture has to go somewhere.

 

[JP Reef]

Where do your bathrooms vent to? I would suspect that that is a more likely scenario. I have a similar size tank, and I am pretty confident that no moisture makes it to my attic. You would need a significant draft to pull all that air to your attic. I would think that you would see moisture on your ceiling before you would see it in the attic. What type of heating do you have. Most furnace's during the winter would dry the air enough. I have to run humidifiers to add enough moisture else it is uncomfortable.

 

[SoloGarth]

Public Service Announcement: Evaporation and Mold

Where do your bathrooms vent to? I would suspect that that is a more likely scenario. I have a similar size tank, and I am pretty confident that no moisture makes it to my attic. You would need a significant draft to pull all that air to your attic. I would think that you would see moisture on your ceiling before you would see it in the attic. What type of heating do you have. Most furnace's during the winter would dry the air enough. I have to run humidifiers to add enough moisture else it is uncomfortable.

Since moisture condenses on cold objects you would not see it on the ceiling no.

Forced hot air furnace. Bathroom vents to outside via a fan. The main Bath is on the 2nd floor with another floor above it.

It is my understanding that the moisture in the air can pass through the drywall. It continues on until it comes in contact with the freezing cold plywood of the roof. It then freezes instantly to the roof and starts building up the ice layer.

Why would you suspect the bathroom over the tank? The tank absolutely evaporates more water into the air. I should add that only two people live here and the exhaust fan is run during showers.

I don't have an attic (small crawl space above center section of roof). The house has 15' ceilings. The roof is:
Shingles
Plywood
9.5" r30 insulation between 2x10s (this is one of the major issues)
Inner sheet rock.

Just curious since you say you are fairly confident that no moisture makes it to the attic; have you checked? I was fairly confident too. I used to run a humidifier during the winter (only for a little while as it didn't seem to help: was probably just adding to ice on bottom of the roof) for the same reason you mentioned. I had no idea this was happening until we started cutting holes in the ceiling to look.

 

[SoloGarth]

 

[SoloGarth]

I should also add that the previous owners of the house didn't have this problem. I know because there was no staining of the ceiling. House built in 92. So it was fine until the last 5 years while I have lived here with my tank.

 

[JP Reef]

When was the last roof replacement? Over 20 years is a long time on a roof. Is the space vented? No ice has ever formed on the underside of my roof and I put in more insulation during the coldest days of the winter a few years ago, so I would have noticed. My bathrooms also vent to the attic. My attic is also vented to prevent any of this.

I could see this possibly happening if you didn't have a vent to allow the moisture and air to exchange.

 

[SoloGarth]

When was the last roof replacement? Over 20 years is a long time on a roof. Is the space vented? No ice has ever formed on the underside of my roof and I put in more insulation during the coldest days of the winter a few years ago, so I would have noticed. My bathrooms also vent to the attic. My attic is also vented to prevent any of this.

I could see this possibly happening if you didn't have a vent to allow the moisture and air to exchange.

Current shingles are 6 or 7 years old I think. I'm not sure if the plywood was replaced then as well.

The top section is vented. The sides not so much. It was designed to be vented but I don't think the implementation resulted in this working well. It certainly is a problem caused by the way the house was built: no vapor barrier other than the paper on the underside of the insulation, closeness of insulation in the sloped roof space. But it wasn't anywhere near as bad (likely not a problem at all) before there was a reef tank evaporating water at all times.

My purpose here isn't to argue whether the tank is causing the problem: that in my opinion is beyond dispute. I just wanted to bring it up. If someone had warned me it could have saved me a lot of money and trouble.

 

[ca1ore]

That sucks. Watched an episode of forensic files where a family were poisoned by mycotoxins, so I went on a mission to inspect every area of my house. No mold anywhere. My tank has been running for most of the last 20 years, and it doesn't raise humidity as much as a normal August day. Turns out that mycotoxins are incredibly rare and that most molds are relatively harmless (a bit of hay fever according to the CDC).

BTW, when I had my roof replaced the contractor made a big fuss about needing a ridge vent. But he never apparently realized that you also need soffit vents in order for it to work properly. Typical knuckleheads.

 

[SoloGarth]

That sucks. Watched an episode of forensic files where a family were poisoned by mycotoxins, so I went on a mission to inspect every area of my house. No mold anywhere. My tank has been running for most of the last 20 years, and it doesn't raise humidity as much as a normal August day. Turns out that mycotoxins are incredibly rare and that most molds are relatively harmless (a bit of hay fever according to the CDC).

BTW, when I had my roof replaced the contractor made a big fuss about needing a ridge vent. But he never apparently realized that you also need soffit vents in order for it to work properly. Typical knuckleheads.

This is exactly what I want to hear about thanks. It is good to be sure. My father is a contractor so when the roof is repaired in the spring I'm having it done right. Complete vapor barrier and proper venting. This is just one of the many situation where what might be fine otherwise becomes too pressed by large aquarium.

And yes I fervently hope that this mold is not the deadly type. I assume I've been living with it for years without knowing it was there but still trying to be careful.

 

[wildman926]

This is a very good scenario to justify running glass tops, to help with evaporation and condensation. You only lose 5-12% (can't remember exactly the number) of light, but it sure is worth it considering what you are posting. I have a 90g and 150g, and I fill each ATO's 5 gallons every week to 10 days. My A/C takes care of any humidity issues.

 

[SoloGarth]

This is a very good scenario to justify running glass tops, to help with evaporation and condensation. You only lose 5-12% (can't remember exactly the number) of light, but it sure is worth it considering what you are posting. I have a 90g and 150g, and I fill each ATO's 5 gallons every week to 10 days. My A/C takes care of any humidity issues.

Well a glass top has some negatives. For one is greatly decreases gas exchange. Also my tank is rimless and a glass top would ruin it's rimless vibe. Haha.

The dehumidifiers remove 1-2 gallons per day from the air. They also make the house feel much more comfortable.

 

[slief]

This is a very good scenario to justify running glass tops, to help with evaporation and condensation. You only lose 5-12% (can't remember exactly the number) of light, but it sure is worth it considering what you are posting. I have a 90g and 150g, and I fill each ATO's 5 gallons every week to 10 days. My A/C takes care of any humidity issues.

The problem with glass tops is that they can have a big impact on gas exchange in our tanks and fresh air across the waters surface is a big part of that as it adds needed o2 into the water. The protein skimmer alone isn't enough for that.

Having said that, I've had my 480 gallon display setup in my home since 1997. My system volume is about 650 gallons and I have had no issues with mold or humidity and I don't run dehumidifiers either. I evaporate about 5-6 gallons a day. What I did to mitigate humidity issues was to install a vent from the lighting soffit above the tank that's ducted to the outside of my house. It uses a 10" 550 cfm Rotron fan to suck the air from above the tank and push it outside the house through a 10" duct. There is also a channel in the wall of the peninsula that allows some air from below the tank to be drawn up to the light soffit. Fresh air enters above and below the tank through the small gaps in the doors. The fan runs 24/7. I also used moisture and sound barrier drywall above and below the tank as well as insulation in the walls surrounding the tank. The inside area above and below the tank were then covered with with FRP to further protect the walls and give a nice clean look that will last a lifetime. I also added a pond liner below the tank to contain any leaks and further protect the walls.

This last summer, I had a copper line break in the slab and we opened some of the drywall up around the tank and there wasn't any mold at all. A bit of planning can go a long way in preventing these issues. At least if your tank is next to an exterior wall. For me, that was key when I bought my home. I had 3 criteria. A place for my tank as I already had it setup at my previous home, a 3 car garage and a good place for my home theater. I was fortunate enough to find a home that met all those criteria and the home layout allowed me to duct the heat and humidity above the tank to the outside. That for me was the key to not having humidity issues, let alone mold issues.

One thing about dehumidifiers is that they will accelerate evaporation so keep that in mind. When I had that copper line in my slab leak, there was moisture in some of the walls in the pantry and bathroom near the tank. Dehumidifiers were setup to dry out those spaces. Much to my horror, my tank evaporated 60 (yes 60) gallons of water in less than 24 hours. I about lost my mind when I found my 100 gallon RODI holding tank 75% empty.. These were obviously big dehumidifiers but even smaller once can accelerate evaporation in our tank substantially.

 

[wildman926]

The problem with glass tops is that they can have a big impact on gas exchange in our tanks and fresh air across the waters surface is a big part of that as it adds needed o2 into the water. The protein skimmer alone isn't enough for that.

Only if the glass tops totally seal the top of the tank. If someone were to use the glass tops provided to them from the tank manufacturer, they will have a 2" gap at the back. If someone has the glass tops made, then they should do that as well.

An open sump also allows for gas exchange as well.

 

[SoloGarth]

Only if the glass tops totally seal the top of the tank. If someone were to use the glass tops provided to them from the tank manufacturer, they will have a 2" gap at the back. If someone has the glass tops made, then they should do that as well.



An open sump also allows for gas exchange as well.

Sure for an All-Glass tank. But I have a custom rimless. It didn't come with a top and one would look pretty unsightly on it.

 

[slief]

Sure for an All-Glass tank. But I have a custom rimless. It didn't come with a top and one would look pretty unsightly on it.

A 2" gap across the back of the tank won't allow as much gas exchange as an open top. While the sump does allow for some gas exchange, the sump doesn't have near the amount of surface agitation that the display should and that surface agitation is key for good gas exchange. Yes, having 2" open is better than nothing but the more you have the better. Especially in tanks that have heavy fish loads. Interestingly enough, I do have my sumps covered to limit evaporation below the tank. Since my display has a pair of 24"x24" openings in the 4'x8' top, having my 40"x36" sump and my 36"x30" refugium covered probably helps to reduce my evaporation more than covering the openings on top of the tank would.

 

[SoloGarth]

Agreed. For many people, my self included, a glass top is not an acceptable option. In addition it isn't really a solution to the above problem as evaporation will still occur (even if at a lesser rate).

 

[wildman926]

Sure for an All-Glass tank. But I have a custom rimless. It didn't come with a top and one would look pretty unsightly on it.

Agreed. For many people, my self included, a glass top is not an acceptable option. In addition it isn't really a solution to the above problem as evaporation will still occur (even if at a lesser rate).

Well, each design of our aquariums in the hobby, have their pitfalls. An open top rimless tank will have too much evaporation as one of their pitfalls. I don't have evaporation issues and mold, running twice the volume you are with both tanks combined. Sure there is evaporation, but not to the degree you are experiencing where it would be a possible health hazard.

I also don't have issues with gas exchange, or light penetration.