[scout]

Well I just drove to NORTH NJ today and bought a Hamilton Tech Oak Hood setup. (It was posted on RC). It has 2x175 20k's and 2 VHO with fans at both ends and a plexiglass slide-in shield.

This was to set on a 72 gal bow. Won't work unless I take glass off tank. Doors won't open. Looks like I will need to hang from the ceiling. How high should I hang it above the water? Should I keep the glass on top of the tank? I really want to, due to the evaporation issue. My 30 gal, with no top, easily loses twice as much water as my 72 gal. Secondly if I do leave the glass on, do you all think it's nessary to keep the plexiglass on the hood?

BTW, those 20k light really make the tank blue, after seeing the 10k vs 20k experiment I think I'll go with the 10ks next bulb change.

Thanks
Mike

[Reefland]

I think the bulbs would be great 5-7" from the water surface. I would also remove the glass from the top of the tank. The evaporation may be a problem as far as adding additional top off water but also remember, any new water we add to our tanks is also adding beneficial elements such as calcium.

Scott Z.

[scout]

Hey Scott,

We're adding calcium in our top off water? I use RO, where's the calcium coming from? I realize I get that benefit when I change water and mixing the Reef Crystals, but never thought I was adding anything beneficial when just adding "top off" water.

Does leaving the glass top on cause a substantial loss of benefit to my corals? Decrease wattage getting to the bottom of tank?

As always, thanks!
Mike

[Reefland]

Sure, top off water contains other elements that are beneficial to our reefs as well. As far as calcium, it surely isn't enough to maintain proper levels but I would definately guess there is some level of calcium in water. There are also other beneficial elements to top off water.

The covers will surely reduce the amount of light, especially when the glass is due for a cleaning. I don't think it will significantly impact your corals but heck, we spend all this money on lights, le's make sure we give them as much of it as possible!

Once you move to MH and add the additional heat from the lights, the evaporation could become an efficient means of keep the water cool as well. Covers also impair oxygen exchange which is needed. If you want to reduce evaporation, perhpas you might consider just covering the sump?

Just some thoughts,
Scott Z.