my new tank, I installed a bathroom fan over the tank. variable speed fan with a humidity switch.
the humidity goes up fan goes on

Thank you for the suggestion.

With an HRV you'll be fine. Even better with AC.

When I moved into my current house, halides were still the thing and I did have humidity problems in winter and I think I only had the 75g and a 72g at the time. But the halides, beautiful as they were, and the fans to keep temps regulated, literally pumped water into the air. I had to admit defeat, and put in an HRV. It literally solved the problem overnight.

Now that I know what an HRV is and what it does, I want one in whatever house I live in, tanks or not, they're just really useful.

When the 280g went online I ran 3x400W Radiums. It was a sight to behold, but, that HRV for sure earned its keep, never had a problem.

Nowadays though I run a 280g with mostly LED and some T5, and between that and the terrariums, vivariums and my other indoor jungle, there's still so much less humidity than with the halides, that I only need the HRV on pretty much the lowest setting.

With the latest cold snap, I do get some frost on the windows overnight (the main problem is the window coverings trap humidity) but when I open the blinds in the morning, the windows are defrosted and dry within half an hour.

Nowadays my humidity problems come from my 13 year old having luxurious 45 minute hot showers. The bathroom becomes Costa Rica. I don't think there's an HRV capable of fixing the root cause of this, though. :lol:

Depends on the local conditions. In southern Saskatchewan I have a humidifier pumping steam into a 12x13' bedroom and I can't get that one room above 25%. If I were having problems with the humidity I would try to get to the moisture before it entered the room. Sending it out of the house would pump heat out of the house at the same time. If you had a thick enough floating light hood, you could install a dehumidifier in it that brings in air from under the hood, and pushes the dried air out of the hood into the room. Rather than having a collection bucket to empty, it could just drip back into the aquarium. Could work.

at what range does humidity become a problem?

im sitting at about 50% now. i know its been upto 60 even just a month ago.

i have AC, but obviously not running that during this part of the year.

i do not have a HRV. nor do i really know what it actually is. i do know what it stands for lol.

i didnt think humidity would be an issue as my tank is basically in the center of a very open lay out house. i thought any moisture would just dissipate throughout the house's square footage.

any thoughts?

humidity depends on where you re living as well. being in the west like Manitoba, Sask, Alberta and parts of BC. in a drier climate you wont have to worry about the larger scale dampness due to the dry so yes a 30-50% is normal. In the east where I live the humidity sucks Ass. Winters are wet and cold and I run a heat pump to offset the dampness. Here its easily to get in the70-80% and when your house is sealed its easy to get out the older homes tend to have humidity problems from the older home of it soaking in pretty much lol.

HRV's work but expensive
AC works great but sucks in the winter
a bath room leaving on in a house does wonders as well
humidex machine does as well as a bathroom fan but can be hooked u in the basement to draw the humid air out.

I think it's dependent most on what the outside temperatures are. For me, humidity became a problem when it became colder than -10 or so outside at night, in the mornings I'd find frozen condensation on the windows and stuff like that. Consensation that doesn't dry out can lead to things like mold. So in a way, if you don't notice it, it might not be at problem levels.

For me the HRV was the answer, but as been suggested it isn't the only answer. And I would imagine it depends on what you're dealing with outside. In my case, it's a dehumidifier because the air coming in from the outside is pretty dry. If the air outside was super wet because it was raining then I would think I'm just replacing humid air with more humid air and not really solving the humidity issue (maybe getting fresh air though, which is always a bonus). But having said that though, if was raining outside, that suggests it's probably quite a bit warmer than -10, and therefore I'm probably not dealing with excessive condensation on the windows anyhow at that point.

To a degree having some humidity is actually pretty nice. If I crank my HRV to the max and dry out the house, I may have dry windows but it's also unpleasantly dry. I try to adjust the intensity based on the outside temperature to basically as humid as possible without there being pools of water forming on the windowsills (I can live with a little bit of window fogginess as long as it dries out during the day). When it's super cold outside I have to have it set higher, but on most "normal" winter days that's not necessary.

Also beyond out own comfort, if you have hardwood floors, those will need some degree of relative humidity in the house.