Evaporation?

[Bill Moore]

One of the more surprising revelations of my first winter with my "Plan B" aquaponics set up in the basement is the amount of evaporation taking place in the system. I haven't yet measured the humidity level in the basement, but it doesn't seem overly damp.  Could be co-locating in the furnace room is part of it and it's been an unusually warm and dry winter here on the northern plans. I am having to add as much as 4 gallons of new water every couple days.  

I plan to buy a humidity gauge to measure levels in the basement.  I just want issues with mold developing.  I run a small fan on the floor next to the sump and fish tanks to prevent any damp spots from developing.

[Carey Ma]

That humid? I would think that even in a basement, most moisture would go through the floorboards into the living area, especially in winter where humidity is usually pretty low. I'd worry more come summer. If you have problems now, you will definitely have problems when it gets hot.

[Carey Ma]

PS evaporation can be limited by covering the tank with a sheet of plastic but make sure your air pump is running properly.

[Jonathan Kadish NYC AA Chair]

I have a small system of 26 gallons and I lose a bout 2 gallons a week. I think this is in line with the expected 2-3% per day that is predicted.

[TCLynx]

If your water is warmer than the air temperature in the basement and there are any "cold walls" or other cold surfaces, those are where you should watch for the damp problems.  I would recommend one of those little thermometers that also tells you the relative humidity so you can keep an eye on it.  Keep in mind that out in the middle of the room in warm air the relative humidity may be low but up against a cold wall or window, the relative humidity is going to be higher because the cold air can't hold as much water and the moisture is likely to condense on the cold surface.  (This is why so many of the old underground homes didn't work so well.  People thought "oh the earth is a great insulator" but the truth is it's a great thermal mass and it is only effective as an insulator if your desired temperature happens to match the temperature of the earth.  Since most people like their homes a little warmer than ground temp in much of the country and the activities of modern households tend to put much moisture into the air and then that moisture would condense onto the cold "earth temp walls" causing damp and mildew problems.  So Insulate the living space if doing it underground.)

A dehumidifier might be appropriate if you do see any "damp" problems.

[Jonathan Kadish NYC AA Chair]

That would be fun... use the dehumidifier to top up your tank :)

[TCLynx]

Warning, dehumiditifer water is generally not SAFE.  You would have to treat it before using it since the condensation fins are generally not cleaned nor easy to clean they can become a breeding ground for all sorts of bacteria and the water condensing on them will be full of all sorts of stuff.

[RupertofOZ]

Is it actually evaporation that's occuring... on plant transpiration through the leaves???

 

Tomatoes for instance... can suck a large amount of water... and throw most of it out through their leaves...

[Bill Moore]

Good point.  No tomatoes, but plants are going larger, so could be some transpiration.

[RupertofOZ]

It's not unusual for systems to lose 10% of volume per week.. through transpiration... more in the heat of summer....

 

Presumably, you're under lights... and probably quite warm...

 

Humidity can/does affect transpiration rates...

[TCLynx]

Yep, if you do run a dehumidifier, you will likely have to top up more water since the plants will work to raise the humidity and the dehumidifier will suck that out of the air and the cycle continues.

[claude saunders]

Reminds me of a joke the comedian Steven Wright used to tell:

"I got a humidifier for christmas and a de-humidifier for my birthday, so put them both in the living room and let them fight it out."

[Bill Moore]

You got me chuckling on that one. Thanks, Claude.