height for 90G canopy???

[reef_enthusiast]

Hello everyone,

I'm upgrading my main lights from 2 150W MH's to 2 250W MH's. My current lighting is mounted on an AGA standard 90 gallon canopy. The height of that canopy is 7" and the lights are about 5" from the water surface. Since 250W is gonna add more heat and I have problems with fish splashing water on my current lighting, I am planning on building a new canopy.

I've done lots of searches here for canopies to get ideas. The only thing that I'm having a hard time to decide on is the height of the canopy. Should I make it 12" or 16"? Keep in mind that 2" of the bottom part of the canopy is gonna cover the 2" aquarium trim.


Thanks for the help and replies...

joe

[tang_man_montreal]

I made the canopy for my 90gal 18" tall.
I have 2 x 250w + 4 x 40w flourescents.
I have a 4" Orion fan on each end blowing air INTO the canopy, and the top 4" of the back of the canopy is open.

I have no heat issues to date. :D

[volk23]

Also you need to add is the fact that you live in Canada and thats a big plus for no Heat issues.

[tang_man_montreal]

heheh...

You think it doesn't get hot here?
Today and tomorrow it's 88 degrees, plus humidity bringing it into mid 90's...

They're forcasting 90's possibly next week!

We don't live in igloos you know...

:D

[volk23]

really? damn. I wonder what we gonna have here then tomorrow.

back to the subject tho:

As it has been suggested to be when I was building my tank canopy - you want to keep the bulbs 10 inches away from the surface of the water. Of course adding at least two fans would be a must in this case.

tang_man_montreal, really no heat problems with 2x250 in a 90gallon?? Interesting, what about water evaporation, whats the rate of TOP OFF you think on the hottest day for you?

[tang_man_montreal]

Theweathernetwork.com says you're gonna have 86 degrees... ;)

[tang_man_montreal]

Originally posted by volk23

As it has been suggested to be when I was building my tank canopy - you want to keep the bulbs 10 inches away from the surface of the water. Of course adding at least two fans would be a must in this case.

tang_man_montreal, really no heat problems with 2x250 in a 90gallon?? Interesting, what about water evaporation, whats the rate of TOP OFF you think on the hottest day for you?

Well.. that's the reason for the 18" canopy. My bulbs are way up in the canopy..
The fans blow just below the lights, near the water. Each fan is rated for 55cfm.
Good air circulation is the secret.

Top off rate varies... on cool days, it could be as low as 1/4 gallon, with 1gallon on real hot days.

If you are having major heat issues, put a fan blowing directly on the water. And cool the tank of with evaporation.

I have done this for my 29 gallon, and the heater actually has to switch on the heat the tank up! :)

[reef_enthusiast]

thanks for the replies...

i guess i will be leaning towards the 16" height.

i was curious if you guys run an open top or glass covers on the tank? Sounds like you are running open top. Currently, i'm running an open top. I have a hippo tang in my tank that LOVES to swim to the top and eat food before it even sinks. When he does this, he splashes water up. Being my current MH is only about 5" above the water, it got hit real good last week and ended up cracking the bulb. This resulted in both lights to go out. I have both connected to an ICECAP digital timer. I had a spare bulb and put it in. At 1st, i thought i blew out both of my ballast but it turned out that the digital timer burnt up. So, I was thinking about running glass canopies on the tank but I'm worried that it will just heat the tank up more...

thanks for the help and replies...

[tang_man_montreal]

Running glass tops will definately heat up, and the tank may also suffer bad gas exchange.

It's for this reason (among others) that you have to place the bulbs real high.

In answer to your question... I don't have any glass tops on mine.

If I understood your post... the icecap timer blew because the bulb got splashed and cracked????

[volk23]

no glass cover. i want the tank to get as much air as it can. evaporation is a good thing

[mirski57]

After doing some research, I decided to go with a canopy/hood where the top is 12" off of the frame. It also covers the top 2" of my tank...so really the total height of the hood is 14".

[reef_enthusiast]

tang_man,

actually I don't know if the bulb cracked immediately. All I notice was one day, the lights didn't come on. I checked the digital timer and it indicated that it was on. I would cycle back and forth between on and off and nothing. Then, when I inspected the bulbs, I noticed one bulb had a crack on it. When I went to replace it, it just broke into pieces. Then, with the new bulb, i tried firing them but nothing. I opened up the icecap digital timer and the part of the circiut board that's connected to the hot wire was black. The plastic case near that part was also black.

The timer runs for about $50 - $60 but I was glad it was the timer and not the ballasts that burnt up. Now I'm just running a regular timer from home depot...