well the dehumidifier fills up with water after about 12 hours (i now have it draining directly into a drain. so it must be removing moisture from the air. (a regular fan wouldnt condense and dispense water from the air)

The house has central air but since the fish room is in the same room as the furnace, there are no air outlets in there :(

my room is small (11ftX11) I use a portable air conditioner in the summer.
It's a single exhaust so it's using the air inside to cool itself, evap the moisture and exhaust outside.
When it's cool enough I just have a 6 inch exhaust fan in the top corner of my room, spits air right outside.

Noticed a huge increase in evap when I added the exhaust fan so I'd say it made a difference in humidity.

Correct but why remove moisture from air you're pumping outside? The dehumidifier by itself will certainly lower humidity in the room but if you're taking all the air that it is exhausting out of it and sending it outside the dehumidifier is not doing anything more for you than a regular fan would. Yes you're condensing water but unless your goal is to make water you're not gaining anything from using the dehumidifier.

Is this clear? I'm not sure if I'm explaining this well, maybe others can help.

no i totally understand. because its not replacing moist air with the dry air, its just pulling more moisture from the rest of the house.

i just dont think theres any way for me to use this. the heat it produces raises tank temp to 81.5.

looks like ill just have to get an AC unit for the fish room.

But it's not pulling "more moisture" than just a fan alone would. Unless you agree with that statement you don't completely understand.

If heat isn't an issue without the dehumidifier and you have a way of exhausting air outside from the fish room I'd suggest just using an exhaust fan to control humidity. By venting air outside you're exchanging air, new dry air will enter the room as needed from the rest of your house. No need for an HRV, it really won't help in summer months, only winter and more than likely humidity isn't much of a concern in the winter.

my issue is that that rest of the house is about 50% humidity. and id like to get my fish room down to 35% because its in the same room as the furnace,boiler, electrical panel.

a fan will just keep it at 50% like the rest of the house, right?

Totally agree with you. I run a 500 CFM exhaust fan, works great and the room air is replaced by the air conditioned area in my home.

Yeah in theory but depends if we're talking about real humidity or relative humidity. We measure relative humidity which is a percentage of how much moisture is in the air relative to how much moisture the air can hold at it's temperature. So if air is warmer in the fish room which is typically the case due to equipment then your relative humidity could be lower than the rest of your house. For example 50% humidity @ 20°C is the same amount of moisture as 35% humidity @ 25.9°C

Now if you cool the air with an AC unit you will remove moisture but relative humidity may still stay the same or even increase.

50% relative humility is just fine for your house hold equipment. What you need to be concerned about is if anything the air in the room comes in contact with is cold enough to form condensation but @ 50% relative you'll need a 10°C temperature difference.

I don't really know the specifics. The room is naturally cool (3 exterior concrete walls and interior wall is insulated) and there are no windows. Running LEDs even as room lights to avoid introducing heat

My main goal is to keep the humidity in the room as low as possible to lower the risk of anything being effected by it.

In my old house. I noticed that drawer handles had started feeling rough (like sand paper) even tho they were about 20 feet from the tank.

Anyone know if its possible to disable the heating coil in a dehumidifier?