View Full Version : humidity issue help

06/14/2017, 10:16 PM
i have an issue with humidity level been too high won't go down. It's a 300DD inwall and the fish room about 10X8X8, that's about 640 ft^3. i have a 70cfm bathroom fan run 24/7. I mean the fan should empty the room within 10 mins. outside the room, humidity is about 40-45, but in the room, humidity lvl is from 60-75.
the room is about 73-79 F depending on the time of the day.
tank surfaces 6X3, 4X1.5 and sump 2X5. running SM 200 with RD3.
I am fairly sure the humidity readings since if I left water on fish room floor, it won't dry.
the doors on the facade have gaps to let air in. I also tried left one of the doors open for 24 hrs. no change on the humidity level.

I don't see how the humidity stays so high in the room. does that sound normal?

Vinny Kreyling
06/15/2017, 08:45 AM
Yes, normal.
Can you put a room AC unit in?

06/15/2017, 03:37 PM
no, but I think it's time invest to some smart vents.

06/16/2017, 01:32 AM
Is the fan pushing air in or pulling it out. Latter works much better.

tom obrecht
06/16/2017, 04:44 AM
This is what I did. I also installed a ceiling (bathroom type) fan intially on my fish room. I have a 240, a 40 as well as my sump for both tanks that is roughly 60 more gallons in a room that is roughly 25' x 12'. The fan did very little to help humidity. I purchased an inline fan, cut a section out of the exhaust pipe and plugged it in. In one day the room went to normal humidity levels to the point where you can not tell any difference from the rest of the house. I'd recommend an inline fan vented directly outside.

06/16/2017, 08:24 PM
the air is pulled from the room and go directly outside. looks like I need more CFM.

06/16/2017, 09:10 PM
Get a dehumidifier.

06/16/2017, 09:31 PM
Get a dehumidifier.

you might as well just burn money.

06/17/2017, 06:58 AM
you might as well just burn money.

Well thats a great solution to a humidity problem.

06/17/2017, 09:15 AM
Well thats a great solution to a humidity problem.

no, it's not. this is a short term solution at best.
here's why.
1. it run 350-400w, which is hugely not energy efficient.
2. when it run it put out heat, which will heat up the room and most importantly the tank. now i have to look into way to cool the tank down. if i ended up have to run a chiller which will be very costly way to cool the tank.
3. for the amount of the money i have to spend buying the dehumidifier, maybe even the chiller, i can spend that money to get smart vents and a bigger fan. which can improve your home more energy efficient and more comfortable. i might still come out ahead on the money part and long term much more energy efficient.

moving the humid air outside and let the less humid air comes to into the room is a much better solution.
i just find it surprise/odd the air get humidify so fast.

Vinny Kreyling
06/17/2017, 11:54 AM
There is the fact of a big surface of open water in the room, I'm not surprised.
I had to put in a whole house unit.

Sounds Fishy
06/18/2017, 08:50 AM
It is too bad hydro is so expensive,but with a big aquarium,you need to control house humidity and water temperature,regardless.It really adds a lot noticeable humidity?I like some others, use a portable A/C ,but I also need a separate dehumidifier in the same room as my built in aquarium.I also run a small chiller (not vented outside) and 6 smallfans in the area for circulation direction.It is 100 degrees outside ( with the humidity ) and I keep my [email protected] to 80 degrees . I live in a cottage and this set up cools the whole place.I cannot get the room temp. below 77 ,in the cottage,because of the small size of the A/C unit,however that is still reasonable,given the outside temp.

06/18/2017, 10:15 AM
I had the same issue. I had a dehumidifier and window air conditioning unit to keep the fish room cool and dry.

I also added large vent fans. This helps a lot but unless you have a lot of circulation, you're going to be removing the hottest driest air first. So you can add fans to circulate the air and then a vent to remove it.

In the end, a dehumidifier with a drain outlet does the best work. The problem is in the summer when it gets hot and potentially rainy (more humidity). Then the AC needs to kick in and they can't both be on at the same time... so I added a circuit that switches between the humidifier and AC. Works ok.

Last week, my AC died... working too hard. So I tried a portable 10000 btu AC from hisense with a "smart" feature. Above 79 degrees, it cools. Under 79, it dries. At a lower temperature (don't remember where) it runs the fan to circulate.

That feature just made my life so much easier. It has a 6" duct that I run outside and the hot air coming out is unbelievable. The room dropped from 89 to 79 overnight and the humidity is under 40 again.

Just sharing what's working for me.

06/18/2017, 02:03 PM
thanks for all the input guys. i want a long term energy efficient solution.
i have fan moving air in the room. i have an air to air exchange for my old house, it keep the humidity in check nicely.
i just did some more testing. i am only getting 24CFMish instead of the 70CFM. i know i dont get the full 70, but i dont expect only 1/3.
i think i am going to try pumping more air out before doing anything else.
ordering a 180CFM fan and i will replace all the flex duct with rigid duct to reduce the friction. i might have to increase to 6" duct to increase the airflow too, but let's see what the 180cfm fan can do first.

tom obrecht
06/18/2017, 03:25 PM
I think the fan should do the trick...at least it did in my case and very well at that. I didn't even remove the old ceiling fan and it did wonders! Just to point out I also have tried dehumidifiers in the past with little avail. It pulled a lot of moisture from the air and tank, but when you walked into the room it felt about the same.

06/18/2017, 03:34 PM
I'm having a similar problem in an air conditioned room that is 20x10. The humidity in there is at 100% almost all the time. Granted, all of my tanks are rimless so they don't have a canopy/hood but I'm at my wit's end with the humidity in there.

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07/07/2017, 06:53 AM
that's it, the fan is the problem,the cheapo bathroom fan you can get at homedepot is junk. it rate for 70cfm only 25cfm at best.i switch out to a high cfm unit(rate at 260cfm), now the humidity only stay 3% higher in the room compared to the rest of the house @ only 82 watts. now when i walk into the fish room, i can feel the floor is dry instead of feeling the floor is wet. so i left some RO/DI water on the floor overnight, all dry up this morning.

07/07/2017, 06:59 AM
If your air conditioner isn't able to keep humidity under 100%, then it's not working right.

Is it a window unit? Split? Portable?

07/07/2017, 12:36 PM
I have a basement sump with books: a Frigidaire dehumidifier is fairly economical and works well Don't need it except in rainy season, but it's there as needed.