Hood ventilation.

I have installed two small fans in the hood of my tank to get rid of heat from the lights and also moisture which forms on the perspex cover for the lights. At the moment i have both fans sucking the heat and moisture out. Is this a bad idea? Should I have them blowing air in, or perhaps one blowing and one sucking? I have had the fans going for a long time now and I also have a problem keeping my carbonate hardness levels up and I was wondering if this could be due to the fact that the fans are sucking oxygen out of the water as well. Any theories on this?

 

The best way is to have one fan blowing in and the other fan blowing out, of course, at opposite sides of each other. Only draw back to the fans is that your evaporation rate will increase. Meaning that you will need to top off more frequently.


Luna

 

Thanks Luna. I do have lots of evaporation, about 5 liters (1.3 gal) every 2 days on a 60 gallon tank.

 

The fans shouldn't have any effect on your Carbonate Hardness (KH). Also the fans won't suck any oxygen out of the water. As a matter of fact, the fans will actually improve gas exchange (O2 into water and CO2 out of water) if they are blowing hard enough to ripple or otherwise disrupt the water surface. Hopefully you have powerheads also cause ripples or diruption of the surface film.

 

Oh yeah, I forgot to answer that Q. Your DKH issue has nothing to do with the fans. You'll need to test for Mag and Cal and see where you stand in those elements. Most probably is that your either low on the Mag side or too high on the Cal side.

Luna

 

If you can keep both fans sucking air out and cut some intake holes on the side opposite the fans. You dont want to suck the air out you want to suck fresh air through.

 

Another thing I forgot to mention, corals use ALK/DKH to be able to absorb Cal, so if you have a lot of stonies, that could also be your problem. I have the same problem with Alk/DKH and Cal. Have to dose it every week.


Luna

 

Thank you for the reply. I do have a power head and 2 wave makers rippling the surface.

 

Thanks for the advice. The hood has large vents at the top and fans at the side, one at each end,so it actually sucks air past the ballasts keeping them cool.

 

Thanks again Luna. My cal is at 420 and my mag is around 1140 and I am currently in the process of increasing the mag level.