Question about MH/VHO light hood getting wet inside

[ShirleyM]

Hello,

Last December we took the plexiglass shield out of our light hood on the 120G and, after reading posts, etc, decided to leave it out. It had cracked and kept, imo, substantial light out of the tank.

Today we are replacing the fan with a new one that has a thermostat. The inside of the light hood is quite wet with condensation and such from the tank. It's mfg for the tank, not home-built, and the lights, 2-175W 10,000K MH and 2-110W VHO, are only about 8-9" off the water.

So, is it OK for the water to get up around the fittings and such? It has been for a few months now...

The new fan has a thermostat probe. Does it matter if it gets wet - it'll be attached up in the hood, but will get salt condensation on it.

Thanks,
Shirley

[Piero]

Hey Shirly,
With ample circulation and ventilation inside the hood, there should not be any condensation. I don't remember ever seeing the roof of my hoods wet with condensation.....but idunno. you can also paint the inside of your hood w/waterproof paint....

Most of out lighting components should not be getting wet though, that's for sure. anyone else got any thoughts?

[rabeiler]

Shirley,

Tried to find posts here that would have directed you to not use a shield between your MH and the tank. Couldn't find anything specific so I could better understand the information you had received.

It is my understanding that the shields are designed to block some of the UV wavelength light. It may also be that the MH bulb technology has improved over the years and he shield is no longer required or the UV is okay for certain tank inhabitants.

I would be concerned regarding the problems that you are currently having. I would also be concerned about salts and other materials collecting on the MH bulbs. I have used these types of bulbs extensively in the theatre arts and the color spectrum and life span of the bulb can be greatly reduced by oils from your fingers, etc. I am sure SW is not great for them either. My fan pulls air through a filter from outside of the light fixture so that it gets filtered somewhat for dust.

If your ballasts and other items are external to your fixture (most likely), the condensation is not a big issue. I would be most concerned with excessive UV at the top of the tank and the degradation of the MH bulbs due to salt condensation and dust.

Ross

[ShirleyM]

Hello, and thanks to both of you.

The ballasts, etc are all on the outside. Icecap ballasts on a shelf.

The fan pulls air through the length of the hood (filter on one end) and blows out the other end. The thermostat regulates the fan speed.

There wasn't much salt on the MH bulbs at all, but the top of the hood (understide top) was pretty wet. I'll wait and see what else gets posted. The plexiglass piece that came with the unit used to get dirty really quickly and block light. Then I read somewhere on this board serveral mos ago where people weren't using anything between their lights and the water. (we have an eggcrate top in front and behind the light fixture, and now nothing beneath it.

**Note: My husband said he thinks it's more splashed than condensation.

Thanks,
Shirley

[Casey]

Shirley only the hqi bulbs need the shield Mogul base dont need it, Also dont worry if the probe for the fan gets wet I have had mine fall in many times with no problem just take it back out and dry it off and I stapled it to the hood now I would be concerned about the wetness maybe you need another fan blowing way up high to help with condensation.

[ShirleyM]

What's Mogul mean?

The lighting unit is 6-1/2" high, 8" wide at the top, 13 wide at the bottom, and the fan is 4". The lights are actually only about 4" above the water surface to the bottom side of the MH bulbs. Hope that's not too close. Been that way over 4 yrs with us and 18 mos with the orig. owner.

THANKS!!
Shirley

[Casey]

Originally posted by ShirleyM
What's Mogul mean?

The lighting unit is 6-1/2" high, 8" wide at the top, 13 wide at the bottom, and the fan is 4". The lights are actually only about 4" above the water surface to the bottom side of the MH bulbs. Hope that's not too close. Been that way over 4 yrs with us and 18 mos with the orig. owner.

THANKS!!
Shirley

Shirley mogul base is the part in the pic I have circled 4 in sounds to close for my comfort but if it has been working then let it ride I still would add more fans to help with condensation.

[ShirleyM]

Thanks, Casey, I'll show the pic to Steve. If you mean the screw-in end, then yes, I think that's what they are.

There isn't any more room for more fans. The hood is also factory-made and is black metal of some sort with white inside, with silver reflector on the top of the inside.

You know, it's been running since 9:30 this a.m. and I just looked up inside it and there's NO water or moisture. I don't know where all that water came from. It had already been taken off the tank to install the fan, and that was this a.m. before any lights were turned on. ????

Shirley

[Casey]

Originally posted by ShirleyM
Thanks, Casey, I'll show the pic to Steve. If you mean the screw-in end, then yes, I think that's what they are.

There isn't any more room for more fans. The hood is also factory-made and is black metal of some sort with white inside, with silver reflector on the top of the inside.

You know, it's been running since 9:30 this a.m. and I just looked up inside it and there's NO water or moisture. I don't know where all that water came from. It had already been taken off the tank to install the fan, and that was this a.m. before any lights were turned on. ????

Shirley

Hummm metal canopy never seen one , maybe a fish splashed it up there,I would think the heat from the bulbs would keep the moisture down enough also thats weird.

[ShirleyM]

It looks sorta like this, only it has the airintake on one end and the fan on the other, and places for two MH bulbs at either end.

http://www.premiumaquatics.com/Merch...ode=Icecapvhoh

Shirley

[Casey]

oh ok now I see well just keep an eye out for water and see if it keeps doing it.

[AquaticCo]

Personaly I would be carefull. No mater what you do, salt water and electricity do not mix very well. You may be fine right now but constant exsposure with your lights that close to the water will adventually cause a problem. Also the salt on the bulbs takes away a lot of the lights potential output. Have you thought about going to tempered glass instead of acrylic, a lot easier to clean and a far better product.

Doug

[ShirleyM]

Tempered glass? Yes, we could do that. The plexiglass came with it and fit into the little slide-slots under the hood.

It's been dry all day. I have no clue where the water came from this morning.

[tdwyatt]

Originally posted by ShirleyM
..You know, it's been running since 9:30 this a.m. and I just looked up inside it and there's NO water or moisture. ... It had already been taken off the tank to install the fan, and that was this a.m. before any lights were turned on...

Hmmmmm...

A tight, metal enclosed canopy, left at night over a tank of 80 to 82 F water, in a house where most likely the temp in 75 or lower...

The metal cools quickly, acts as a heat sink, thereby quickly cooling ambient air temps inside the hood, prolly inadequate ventillation if it is a tight metal hood... During the day the lights keep the metal hot enough to dry the hood as they heat up in the morning, or prevent the hood from being cool enough to allow for the heat gradient during the day (i.e., cool metal vs. warm moist air)...


...lights go out, sheet metal cools quickly, moisture comes in contact with the sheet metal, and 'voile, instant condensation... prolly has been happening every night for quite some time. Mostly it will be just water if it is condensation only, but if there are returns or H.O.T. filtration devices at the surface where there may be some spray or bubbles, then salt will be part of the mix.

Just increase your circulation or raise the hood a few cm from the top edge of the tank with the use of wooden blocks around the edges/corners to allow more air into the hood. If the hood is that tight, you may see issues with continuing lower pH values as a side effect. dunno, might be an issue for you, might not.

hth

[ShirleyM]

Thanks, Tom! That all makes sense (of course! )

The hood isn't that tight - it stretches across the center of the tank end to end, with strips of eggcrate covering the spaced in front and behind, but we can use more water flow -- have another Maxi1200 yet to install. If I put it up on blocks, well, I would like to not have to do that.

I'll see what I can do.

Thanks!
~Shirley