Help With Hummidity Please

[Medicine Man]

In the winter it probably wouldn't be a problem. Just the summer. I have an HVAC/Heating/AC consultant coming tomorrow to give me their advice and hopfully install whatever I need. I'll let you all know what he said to do. Thanks again everyone for the help!

 

[jnarowe]

Ouch..that's gonna hurt!

 

[Shaun120]

Now I'm no scientist but I did take some science classes in college so correct me if I’m wrong.

At 100% humidity water will not evaporate because the air is completely saturated. So if you vent out air from the fish room to the outside and replace it with outside air in the summer at 90% humidity it will only be a 10% reduction. Still not enough in Springfield MO, summers here are like Purgatory! Ok so what to do? Well installing a dehumidifier will reduce the humidity in the air. Decreasing the humidity will increase the rate of evaporation of the tank in the space relative to the surface area that is exposed to the air. Now if you know the evaporation rate of your tank you can determine what you need to keep up with the evaporation (adds humidity) to decrease it to a desired level. I don’t know but there must be some way to calculate evaporation based on surface area and relative humidity.

I know what your thinking…get to your point.

Decreasing your humidity in your fish room will increase the evaporation of your tank. So figure out how much it will evaporate at your desired humidity level (say 50% to retard mold growth) and maybe that will help determine the resolution to your problem. How big of a dehumidifier you will need or other solutions available are related to the amount of humidity you need to take out of the air. In some areas of the country the relative humidity is low all year so venting higher humid air from the fish room and exchanging it with the lower humidity air outside will work, an example would be a swamp cooler. This is not really an option in the summer in high humid areas of the country, but would work in the winter when the humidity is lower. Basically you will need some way of reducing humidity through condensation by a dehumidifier or your home air conditioner.

I am really interested in how to work with this situation since I am setting up a 225 in my basement with a 120 growout tank, 60 gallon sump and an existing 68 gallon system already running. Currently I am running a dehumidifier and am able to keep it at 50% with just the 68 gallon. Is there anything out there you can set up to kick on the dehumidifier when the humidity gets at certain point? My dehumidifier’s fan runs all the time and the compressor kicks on only when it is needed so the power being used by the fan is probably not too much.

I have thought of running an adjustable duct from my fish room to the warm air return of my home’s air conditioner to assist the dehumidifier in reducing the humidity but am afraid of additional corrosion that may occur. Has anyone ever tired that?

By the way…I am unaware of salt being part of evaporation. Water evaporates H2Oand leaves the salt NaCl behind that’s why you top off with RO and the salinity increases with evaporation. The high humidity will cause a higher rate of corrosion though.

Sorry for the long post and if I have made any errors in my analysis of humidity.

 

[jnarowe]

That is precisely why I encourage reefers to find non-dehumidifier solutions to tank room humidity. As you dehumidify the room, evap increases. It's sort of a never ending cycle using energy to create a need for more energy.

 

[mcrist]

Some things that I want to point out…

1. A heat exchanger will not reduce the level of humidity in your home if the outside air is also high in humidity.
2. Just running a vent and fan to the outside will cause negative air pressure inside your home. Your house will then pull air from wherever it can to stabilize the air pressure inside. This will cause your house to absorb outside air from any openings it can find. Once again if the outside air is high in humidity you will pull the moist air in. One other thing to note if you have negative air pressure in the basement and your house is exposed to Radon you will increase the amount of Radon gases entering your house unless you completely seal the basement.
3. A dehumidifier uses the most electricity but the only option that gives you the greatest amount of control if your outside air is ever high in humidity otherwise the heat exchanger will work best.

also…

The rate of evaporation is influenced by three things:
1. Air movement above the water
2. Temperature of the water and the surrounding air
3. Humidity in the surrounding air

Any one of the above will influence the rate of evaporation

 

[8BALL_99]

But its not a never ending cycle.. Shaun even said that,, in so many words anyway.. If your room is at 55% humidity then your tank will only loose a some what set amount based on water surface area and room temp.. If you simply find out how much your Tank Evaps with your room at 55% thats how much moisture you need to remove from the air to keep that room at 55%..

Example my old 72 gallon use to evap around 1.5 gallons a day with a room temp of 70 and a house humidity of 50% So all I had to worry about was the 1.5 gallons... Yes at higher humidity levels in the house it might have only evaporated 1 gallon or maybe even less.. But who wants to keep their house at 70% humidity so their tank only evaps 1 gallon lol..

His problem isn't really finding out his Evaporation rate.. Its simply how to control the moisture and the temp in the room. IMO he will end up running a dedicated Ac in the summer and a Dehumidifier in the winter..

 

[Medicine Man]

Ok, the HVAC/Heating/Cooling guy came out today and wants to put the dehumidifier into the main room where the display tank is and open up a duct into the fish room from the AC/house ventilation system and put an exhaust fan in the room with a humidistat/temp controller on it. He said that way the room is supplied with dehumidified air by the house AC system without pulling moisture directly from the fish room. When humidity climbs then the exhaust fan will pull out the air until it drops again. The exhaust fan was supposed to be put in today also but it was raining here so it will have to be done tomorrow or the next day. I'll let you guys know what happens

 

[mcrist]

What brand/model dehumidifier did he recommend?

 

[Medicine Man]

I had already purchased a dehumidifier prior to him coming. Its a Whirlpool 70 pint from Lowes. Seems to work well and came with a 5 year warranty. My one from Sears came with a 90 day and broke after 91-92 days.

 

[mcrist]

Is the 70 pint per day unit working well for you? With 425 total water volume I would be concerned about it working to hard to keep the humidity down. I needed to go with a 135 pint per day for my setup and my total tank volume is about 500 gallons. I also liked the Sante Fe because it only uses 11.4 amps which was less than the smaller units I looked at. I didn’t care for the price so I can understand why you went with I different unit.

 

[Shaun120]

Hey Medicine Man, did the HVAC guy indicate to where the exhaust air will be vented to?

It sounds like his solution is basically what I though I needed to do. I'm wondering if you could vent the exhaust to your air return without problems???

<a href=showthread.php?s=&postid=9692048#post9692048 target=_blank>Originally posted</a> by mcrist

The rate of evaporation is influenced by three things:
1. Air movement above the water
2. Temperature of the water and the surrounding air
3. Humidity in the surrounding air

Any one of the above will influence the rate of evaporation [/B]

Basically what I said...
1. Surface area exposed
2. Maybe you’re talking about temp differential affects on rates of evaporation but wouldn't we be shooting for around 72-80 F for the air and 78-80F in the tank in most cases, so basically not as an issue in our fish rooms? Like I stated before I’m no expert.
3. Absolutely

Please don’t take my comments as negative in any way mcrist, I’m just trying to clarify my understanding (or misunderstanding) of this stuff.

 

[mcrist]

Don’t worry I am not taking any of your comments as negative.

I was just trying to point out a few things

1. What affects evaporation (I did miss one, air pressure)
2. A heat exchanger is an excellent solution only for people that live in non humid climates
3. A dehumidifier may be the only solution for some of us
4. Having a dehumidifier does not automatically cause a vicious cycle of energy use, only when setup inefficiently

Maybe you’re talking about temp differential affects on rates of evaporation but wouldn't we be shooting for around 72-80 F for the air and 78-80F in the tank in most cases, so basically not as an issue in our fish rooms? Like I stated before I’m no expert.

I agree but for a different reason. To reduce evaporation we would actually want to reduce the room and water temperatures. The lower air temperature will cause the air to absorb less water and therefore making the water evaporate less. You could also lower the water temperature which in turn slows down evaporation. Neither one can should be accomplished so therefore it is most likely ignored as a possible solution.