High humidity

Tell us a little more about what your problem is, the size of the room you have the tank in, tank size and any other useful information that comes to mind. Tanks usually lose about 1% of their volume per day (1 gallon for every 100 gallons of water) in evaporation. If the tank is in a small room you may need to run an exhaust fan if you are having high humidity issues, but in general evaporation is a good thing as it adds cooling and indicates good air/water exchange.
 
250 gal. Display tank in living room 13'x13' plumbed to 75 gal. Sump in basement .The humidity has increased to the point of hardwood floors feal damp and mold on window seals.Thanks for any advice with problem
 
I'd look into a squirrel cage fan that can exhaust out doors. If you have freezing temperatures you need to take measures so the outdoor vent doesn't get overwhelmed by giant ice cycles. These can be set to turn on automatically at a pre designated humidity level with a connected humidistat. Green house vendors carry this kind of equipment. If you are worried about exhausting the heat you've already paid for then you may want to look into a heat exchange type system, often used in humid basements.

Even easier - consider some partial glass tops or a semi tight canopy. You may need to sacrifice a little bit of light penetration. Despite all the breathless warnings about oxygen levels you read about, most tanks can handle partial covers quite well. Especially with an uncovered sump in the basement. The exception might be a tank stocked full of large active fish in a tightly sealed house full of people for example.
 
Vent to outside is always good but a dehumidifier may be the best solution (if you can plumb to a drain)

Even a canopy will not limit the moisture that gets into the home. it's just natural to do so when you have that volume of water inside the home and evaporation occurring.
 
Do you live in a cold climate? If so, you might want to invest in a heat recovery ventilator.

That's the term I was looking for in my post! I've seen one first hand and it's the ultimate solution IMO, but not cheap.
 
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Vent to outside is always good but a dehumidifier may be the best solution (if you can plumb to a drain)

Even a canopy will not limit the moisture that gets into the home. it's just natural to do so when you have that volume of water inside the home and evaporation occurring.

Dehumidifier will work fine, but it might be costly to run in a room that size with those large tanks. It also may be a hassle to keep emptying the container as it might be impossible putting a drain system together in a living room. If you go with a dehumidifier, make sure the noise level is acceptable.

A well designed canopy can comtain evaporation and keep it out of the room. Mine does. You will have moisture on the inside that will precipitate back into the tank. So that and salt creep inside the canopy must be accounted for; hence the importance of the right design. May or may not be a good solution for the OP. I should have noted that the light fixture should be isolated within the canopy and not be allowed to run in a high humidity environment.
 
Dehumidifier will work fine, but it might be costly to run in a room that size with those large tanks. It also may be a hassle to keep emptying the container as it might be impossible putting a drain system together in a living room. If you go with a dehumidifier, make sure the noise level is acceptable.

A well designed canopy can comtain evaporation and keep it out of the room. Mine does. You will have moisture on the inside that will precipitate back into the tank. So that and salt creep inside the canopy must be accounted for; hence the importance of the right design. May or may not be a good solution for the OP. I should have noted that the light fixture should be isolated within the canopy and not be allowed to run in a high humidity environment.

Pictures?
 
The tank I refer to is an Red Sea Max 250 and their web site has lots of info on the factory hood. It dramatically reduces evaporation, light spill, jumping and keeping foreign materials out of that tank. It has a small fan in the back to provide fresh air input & exit, but I don't use it. I've run this 65g tank (maybe 55g actual volume) with a top for 6 years with great results. It is packed with corals with up to 6-8 small fish - no oxygen problems.

It has a narrow access hatch for feeding & dosing that can be kept open when and if desired, providing a little more air exchange. A small net screen could easily be fabricated for this as well if desired.
 
65g is a MASSIVE difference in volume to a 250g.

larger tanks are known to cause humidity issues and a simple canopy will not reduce evaporation. Depending on his lighting it could trap heat and require OP to install a chiller even.

There are very good threads on ambient moisture removal for large setups. I would not suggest a half-hearted fix especially given that his flooring is exhibiting issues. He has a major moisture problem.
 
Understand the risks of moisture in the home. Doesn't everyone? I've bought & fixed properties with the problem (non fish tank related). Seen mold up close. Have some greenhouse experience too. And I live in humid Maryland. That's why I clearly suggested ventilation schemes first & foremost, but the OP has provided only sparse details. Just kind of threw the canopy cover idea out there. Didn't know the anti canopy partisan army was out in force today!

Yes, I am also aware of the difference in those two numbers and it isn't really massive at all.

The exposed SURFACE AREA of water (square feet), not tank volume (gallons) is the critical component when talking evaporation. That's what I think was missed. Volume means nothing here.

My tank's surface area is 5.5 sq/ft, OP's 225-250g is probably ~12-14 sq/ft or so. So he has about twice to two & half times more surface area, or 2-2.5x my evaporation potential. Is that massive? Or were you thinking his evap rate was gong to be 4x my puny little tank ? But wait there's more.

Here's the kicker: my total Room Volume is much less than his so the comparison I posted balances out. So it's not a ridiculous comparison. My evaporation potential is much closer to the OP's then a simplistic raw gallon comparison you implied. See, in identical environments our respective tanks could project similar humidity profiles.

I can assure you the RSM250 & any similar canopy can reduce evaporation into the surrounding room while allowing for gentle & sufficient air exchange over the water. The properly designed & built hood contains humid air and precipitates some water back. Have you lived with this canopy or any others? If you saw it in action you will understand. I know b/c I've run it both ways & observed evap & ATO refills in identical conditions. 6 years tells me canopies can defiantly contribute to drier indoor air. Any sized tank can utilize a canopy for drier air if the owner is so inclined.

You are indeed correct that such a set up will run hotter than open top. For me that's just fine as the tank runs at 78-80F all year at my 71F indoor set temp. My 150w heater never comes on and I do have a chiller for AC failure insurance but it rarely comes on. My canopy & T5s are almost like free heat in my case! But sure, heat retention is an issue to consider and it could be a deal killer for many. And some folks just hate canopies. Fine! I like em if they are easy to use and sleek looking. But canopies seem to have gone out of style with the current & popular rimless & LED aesthetic anyway.

For the record I didn't and never would suggest a "half hearted fix" on anything! A careful rereading will reveal the words "a tight fitting canopy" and "well designed". I'm not talking about junk. One COULD be built for any tank to contain moisture to a degree and not suffocate the fish. That's what I'm saying. Just one of many possibilities so I threw it out there. Can't say for sure if it's realistic or likely to be effective enough to solve this particular problem. The OP didn't provide enough details to describe the big picture.

SO, IF YOU WANT TO REDUCE HUMIDITY:

1) KEEP THE WATER FROM EVAPORATING INTO THE AIR, or
2) IF WATER IS IN THE AIR, WRING THE WATER OUT OF THE AIR, or
3) MOVE THE WET AIR SOMEWHERE ELSE, or
4) Sell the tank & take up stamp collecting. It does not cause humidity.
 
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