Condensation & black mould

[Lynnzer]

This topic possibly relates to the hobby in general, rather than specifically to saltwater topics. However the problem of condensation and mould didn't occur when I was doing freshwater.
So, the problem I've been getting for over a year now is that the rooms that have my tanks in, and specifically the ceilings above them, have been getting black mould. The windows in the rooms have also been covered in condensation when I look into the rooms each morning. Naturally this is something I've been trying to get to grips with.
First of all, the small room with 3 tanks in it has been a problem in electricity costs running heaters, pumps, canister filters, wave makers etc. I've now put all the inhabitants into a single larger and wide tank which decreases the running costs. I tried leaving the window slightly open all the time to try and eliminate the condensation and mould but that hasn't had much of an effect as of now so I was considering a dehumidifier, but of course that builds up on the electric bill. I'm still working on ideas for that room.
My other, main, tank is in my study which is combined with my kitchen with an open archway between them. The study has no windows and the kitchens has 2 wide ones. The windows are literally running with water every morning. Leaving them ajar has had little effect. I covered the tank mesh screen with clingfilm to reduce the surface area on the tanks in both rooms and they do appear to have worked as the clingfilm which is underneath the screens gets lots of water on them that collects at the lowest point and drips back into the tanks. I was literally losing around 5 litres a day from the upstairs tank and the downstairs main tank lost about half as much again. I'm certainly not losing that much right now.
I was really going to order a dehumidifier for the study, but tried out a tray full of cat litter placed near the tank for a few days. I have to say that the litter has become pretty moist but the effect hasn't had much impact on the condensation on the windows so that's not going to work.
Then I wondered ....... the kitchen has an extractor fan above the oven and hob. Last night I left the extractor running at half power all night. The windows were completely clear this morning. I figure that a dehumidifier would use a lot more power than an extractor so I'd class that as being a success.

 

[seangee]

I run a small humidifier like this in my study continuously. I have 3 tanks in there (albeit fresh water and partially covered), and it makes a massive difference. The room is closed but not small (converted single garage). Not sure it will cope with the open plan study / kitchen but should do the job in the smaller room. They also do a smaller 500ml version which uses 23W (instead of 40), and of course costs less. This would probably work for my use because I only empty the 1.5l tank about once a month.

 

[GaryE]

Humidity and condensation go with tanks in cool climates in houses with good insulation. There's a reason why my wife told me I could renovate an outbuilding for fish, rather than have fish indoors. Mould was never an issue for me, but condensation was.

I use a dehumidifier, but I don't pay UK energy bills. It is not cheap, and not convenient. It also throws heat, about 2 or 3 degrees above room temperature, and that makes for a warm room.

If the heat loss isn't too extreme, the ventilator fan sounds good. I couldn't do that in Canada.

Would using a standard, summertime ventilator fan help keep the condensation spread out, and keep it from settling on the ceiling?

I am a freshwater guy, so my other solutions are probably useless to you. Open top tanks on paludariums don't touch a reef tank for humidity, although a lot of them have made me a condensation fighter.

 

[MaloK]

You can also use Mould proof paint to do your ceiling (and walls). It does not mean that it wont come back, But it's washable and you can scrub it clean. Strong ventilation toward the ceiling will also help prevent condensation to appear.

Also if you are an handy man you can make a "vapour pressure eliminator". It's a home made device that slowly draws air from the top of your tank directly over the water and passe it trough a tube where the condensation occurs and drops in a plastic pail hosting a fan on top ejecting air in the room. the negative pressure on top of the tank prevents heat to push humidity off the hood in the room. Keep this pail clean and you can use this water to top off your tanks.

 

[Uberhoust]

I am curious about the Vapour pressure eliminator. Do you somehow cool the tube to induce the condensation within it, or does it depend on the temperature difference between the water and the surrounding air.

 

[MaloK]

I am curious about the Vapour pressure eliminator. Do you somehow cool the tube to induce the condensation within it, or does it depend on the temperature difference between the water and the surrounding air.

Nope, with just the air flow, it is impossible that droplet does not form nearly instantly, just by what is called Hydro-static tension, small droplets hitting other becomes bigger and heavier then drop. the others sticks on the wall until more droplet hits them. It helps if your tanks are hotter than air. but it's not a factor. Only the proximity of droplets will do.

It cost nearly nothing to try, the bucket doesn't even need to be air tight as long as you have a sufficient negative pressure under the "hood" water will drip in the bucket instead of going on the ceiling.

Install both the fan and lines on the cover so you can take the pail and switch it for another one quick.

If you want to add tanks you add more air lines and raise the air output. another factor is that your air tubes MUST be (as much as possible) in a straight line to the collector, not much sagging permitted there (air and water must be always able to pass). You can turn corners, But you must always go lower and never under the destination.

Research on marine aquarium humidity management, you will find some inspirations on how to tackle your problem.

 

[Lynnzer]

You can also use Mould proof paint to do your ceiling (and walls). It does not mean that it wont come back, But it's washable and you can scrub it clean. Strong ventilation toward the ceiling will also help prevent condensation to appear.

Also if you are an handy man you can make a "vapour pressure eliminator". It's a home made device that slowly draws air from the top of your tank directly over the water and passe it trough a tube where the condensation occurs and drops in a plastic pail hosting a fan on top ejecting air in the room. the negative pressure on top of the tank prevents heat to push humidity off the hood in the room. Keep this pail clean and you can use this water to top off your tanks.

I found that the Cillit Bang black mould remover works well. I already have this to clean my shower as it also has similar problems from time to time, especially on the shower head.
Lat night was another night with the extractor fan going at half speed and once again there was no condensation on the windows, and with leaving the upstairs fish room window slightly ajar, even with it snowing, all was OK today.
I'm beginning to feel that the new super-efficient double glazing is part of the problem.

 

[GaryE]

I'm beginning to feel that the new super-efficient double glazing is part of the problem.

The more energy efficient a structure is, the tighter it is. In my rickety old flats with lousy windows, I never had condensation. I spent a lot heating tanks though. I designed my fishroom to be heat efficent, working with a contractor, and heat efficient it is. I wish I'd had the budget for an air exchanger.
The room gets hotter than I wanted in winter, even when it's -35 outside, and condensation is ever present (though no mould.... yet).

 

[Uberhoust]

Nope, with just the air flow, it is impossible that droplet does not form nearly instantly, just by what is called Hydro-static tension, small droplets hitting other becomes bigger and heavier then drop. the others sticks on the wall until more droplet hits them. It helps if your tanks are hotter than air. but it's not a factor. Only the proximity of droplets will do.

Thanks. I came across a few types of devices that work on the principles you discussed. Thinking about it you could almost design a canopy that would simply drain the excess moisture back into the aquarium, i.e. vented moisture controlling hood.

 

[MaloK]

I tried, but as soon as you bring the air pressure back in the tank, it voids the negative pressure.

Maybe using a funnel to install the fan on the tube and have it spiralling down to the surface of the tank, it could let the water drip back from the air intake... As air flows up, heavier water drops forming in the tube would drip back down into the tank.