Typical water temp increase from lighting?

[two-rocks]

I've got 3 T5's running on an icecap over a 90gal (the 4th bulb has ballast issues, not sure if I'll fix, replace, or add normal output ballasts, but anyway)....

I see about +2 degrees (from 79 to 81) by the end of the lighting cycle. The bulbs are only 3.5-4" from the water surface. Raising them would help, but light would be lost.

 

[pillowfish]

Seems about normal, does the light fixture have built in fans? If not, then you could probably put small fans to help cool the surface of water and offset some of the heat put out by the lights

 

[two-rocks]

It's a diy retro setup - I have a ducted cooling system with a single fan and individual air outlets cooling the bulb ends. The cooling system wasn't intended to cool the tank or the air between the tank and fixture, just point source cooling to help the bulbs (and works very well at that). I was hoping convective air currents would keep the tank in check. I guess I need to look into a small fan to move the air, and certainly will need something in the warmer months which can't arrive any too soon!

 

[stingythingy45]

diy retro?
Is your lighting set up in a canopy?
JME,but I wouldn't sweat 2 degree change over the coarse of a lighting period.

 

[afboundguy]

2 degrees doesn't sound that bad. Are you overdriving the bulbs with the icecap ballast? If you are then a 2 degree change is IMO pretty good for overdriven bulbs...