Talk REAL slow and 'splain this to me ...

[mikegronholz]

Where did all my d@%& water go !?!?!? I upgraded to the 2x65 lights from a single whatever light. Lights are elevated off the tank and the canopy has 4 fans in it pumping an impresive 120cfm in to cool the lights, plus the 2 fans in the lights. My surface temperature has dropped 2 degrees and the bottom temp has dropped 2 degrees since adding the fans/lights. So where in the h#$% is my water going ? I am topping off a gallon a day in my 20g (5% every day) !!!!!!!!!! That seems a bit excessive. My 75g with a sump evaps 1g per day !!!
With all that rambling, I cannot bring my self to say it's the lights. So, any ideas ?

 

[benj420]

Do the fans blow across the water, or is there something in between?
Also, it's winter. very dry air = high evaporation, even though a gallon is a little excessive.
Fans + dry air could do it.

 

[mikegronholz]

It's water - glass tops - air - lights - canopy lid

 

[broomer5]

That's wild Mike !
My 75 w/sump also evaporates about 1 gallon a day.
I'm sure you know that the things that make water evaporate slower or faster are;
Tank water temperature
Air temperature
The difference between the two.
Water movement
Air movement
The combination of the two.
Open tank vs closed top tank - for obvious reasons as above.
Air relative humidity/dewpoint in the room.
Surface area of the air/water interface ( tank surface area ) - bigger tanks "normally" evaporate more water if ALL OTHER THINGS ARE HELD CONSTANT.
One or more of these on your 29 must be different than the 75.
I wouldn't completely rule out air relative humidity ( even if both tanks are in same room )
Any or all of the above could cause this "excessive" evaporation rate.
Think about both tanks - and do a compare/contrast between the two. The answer will appear to you I'm sure.

 

[mikegronholz]

WEll, water temp is a bit lower in the little tank, and the air temp is as well. Both turn over obscene amounts per hour. Both have glass tops, both have high cfm flowing across the top of the glass tops. Weird !!!
Broomer, I definitely will not disagree...yet as you have more than proven your rational over and over,....BUT I will start taking temperatures and graph them and we'll se what happens. I am a computer guy and I'm sure I have enough "toys" to get high tech on this !!!

 

[broomer5]

Cool - do some data logging and let's play with the graphs !!!
Trying to figure stuff out is soooooo much fun !
Plot away Mike !!!

 

[snowbear]

Maybe I'm full o' beans here, but is it possible that most of that 2 gallons total is evaporating from the sump and the H2O level in the tank is dropping to compensate? You've also checked for leaks, right? Just a WAG as it doesn't seem possible a whole gallon could find it's way through the glass top.

 

[snowbear]

Oops. Doh! I just re-read your post and see that the 29 doesn't even have a sump. The first time I read it wrong and my little brain processed it as a 29 with a 75 gal sump. DUH!! Sorry.

 

[broomer5]

Differences in salinity may affect evaporation rates too - not sure - just popped into my head

 

[kennynj]

mike,
you said the temp. of the water has
droped by 2 degrees, evaporation is
a cooling process. the additional air flow
has increased the evaporation rate of
the water and decreased the temp.

 

[mikegronholz]

WEll, I put 2 and 2 together and figured increased air flow across the glass would col the water a bit, but last time I tried to evaporate water, heat made it turn to steam faster i.e. BOILING it. When I stick water in the freezer, it EXPANDS and makes ice.
Those principals of water is what is REALLY confusing me !!! Cool water evaporates faster than hot water....right ?

 

[slothy]

well with my mh/vho i go through a gallon a day of topoff... same as when i had my pc's

 

[mikegronholz]

you mean my, I mean Debber's pc's I'm going to go broke on this thing !!! I spent $30 in wood for the stand and canopy. Then I spent $125 on lights. Then I spent $150 to keep the d@#$ thing cool !!!!!!! And now I gotta spend $1/day on distilled water for it. I think I'm going to do the 2x65 retro, then add a 250w mh later.