Closed tops and metal halide.

hmello@bermexin · 11/08/2007, 12:23 PM

Okay so I have a 29 gallon Oceanic BioCube. I am taking the stock cover off and adding a 20" 150 watt Coralife Sunpod. What I would like to do is keep the display portion of the tank closed. Don't want eggcrate or mesh top if I can get away with it. This leaves having a pc. of tempered glass cut to fit. I could have this done but I am also thinking about whether a pc. of Lexan would work. Any input form anyone out there?

renisel · 11/08/2007, 01:54 PM

I think having glass over the top would tend to drastically increase the heat issues that come with MH. Not only does the glass absorb some light and turn it into heat, but it also greatly inhibits evaporation (evaporation lowers the temperature of the water). Personally, I would go with the eggcrate or mesh.

hmello@bermexin · 11/08/2007, 02:08 PM

Than you renisel, I thought about the evaporation issue. If you are familiar with the 29g biocube the display is separate from the sump area. I would only cover the diaplay area leaving the sump to evaporate.
I am torn at this point but will keep getting input and figure it out. Thank you for your input, I appreciate it.

renisel · 11/08/2007, 02:35 PM

OK, I guess that so long as the sump has a decent surface area, the evaporation won't be as big of an issue (but it will still have an effect). As for using Lexan, the info I found said its working temperature (the temperature range in which it won't be excessively malleable or brittle) goes up to 239 F. So, I'd put a thermometer below the light at the height where the lexan would sit, and see what the temperature is with your lights on. So long as it's well below 239, I'd think Lexan would work just fine.

hmello@bermexin · 11/08/2007, 02:52 PM

Thank you very much renisel, you went above and beyond what kind of answers I expected to get. I appreciate your time.

JaredWaites · 11/08/2007, 03:38 PM

I don't think you'll have an issue with Lexan, pending how high the lights are away.

Plexiglas is 15X stronger than glass, Lexan is 250X stronger than Plexiglas, and that's not a made up number...but personally since Lexan can be expensive, I'd go with glass if you can...I'd also make sure after you have it cut, that they temper it because I'd hate to see water splash on the glass and shatter your plate glass and make shards, they are a PITA to clean up. Good Luck.

hmello@bermexin · 11/08/2007, 07:08 PM

Jared, will the Lexan discolor - yellow from the heat?

rgulrich · 11/08/2007, 07:55 PM

In the late 1980's, I used a Lexan splash guard under 250W mogul-based metal halides (fan cooled enclosure) with no discoloration for over two years, approximately four inches from the bulbs. I would also suggest the use of a small fan across the top of the Lexan if possible as kind of an "insurance policy" for heat dissipation. Something as simple as an Azoo aquarium fan blowing across the Lexan would work fine to keep things cooler.

Cheers,
Ray

hmello@bermexin · 11/09/2007, 06:53 AM

Good information everyone. Thank you for all of the options. I am going to contact a local glass shop today to see if they can cut and finish the sides of a pc. of tempered glass. If not I will probably try the Lexan route. This of course unless someone else comes up with a better alternative.
Again thank you everyone.

11/08/2007, 12:23 PM	#1
hmello@bermexin Registered Member Join Date: Jan 2007 Location: Michigan Posts: 1,205	Closed tops and metal halide. Okay so I have a 29 gallon Oceanic BioCube. I am taking the stock cover off and adding a 20" 150 watt Coralife Sunpod. What I would like to do is keep the display portion of the tank closed. Don't want eggcrate or mesh top if I can get away with it. This leaves having a pc. of tempered glass cut to fit. I could have this done but I am also thinking about whether a pc. of Lexan would work. Any input form anyone out there? __________________ Henry Somewhere something incredible is waiting to be known. Current Tank Info: 29g BioCube, AI SOL 12" Super Blue

11/08/2007, 02:08 PM	#3
hmello@bermexin Registered Member Join Date: Jan 2007 Location: Michigan Posts: 1,205	Than you renisel, I thought about the evaporation issue. If you are familiar with the 29g biocube the display is separate from the sump area. I would only cover the diaplay area leaving the sump to evaporate. I am torn at this point but will keep getting input and figure it out. Thank you for your input, I appreciate it. __________________ Henry Somewhere something incredible is waiting to be known. Current Tank Info: 29g BioCube, AI SOL 12" Super Blue

11/08/2007, 02:52 PM	#5
hmello@bermexin Registered Member Join Date: Jan 2007 Location: Michigan Posts: 1,205	Thank you very much renisel, you went above and beyond what kind of answers I expected to get. I appreciate your time. __________________ Henry Somewhere something incredible is waiting to be known. Current Tank Info: 29g BioCube, AI SOL 12" Super Blue

11/08/2007, 07:08 PM	#7
hmello@bermexin Registered Member Join Date: Jan 2007 Location: Michigan Posts: 1,205	Jared, will the Lexan discolor - yellow from the heat? __________________ Henry Somewhere something incredible is waiting to be known. Current Tank Info: 29g BioCube, AI SOL 12" Super Blue

11/08/2007, 07:55 PM	#8
rgulrich greybeard Join Date: Jun 2007 Location: MD Posts: 893	In the late 1980's, I used a Lexan splash guard under 250W mogul-based metal halides (fan cooled enclosure) with no discoloration for over two years, approximately four inches from the bulbs. I would also suggest the use of a small fan across the top of the Lexan if possible as kind of an "insurance policy" for heat dissipation. Something as simple as an Azoo aquarium fan blowing across the Lexan would work fine to keep things cooler. Cheers, Ray __________________ The true sign of intelligence is not knowledge but imagination. Albert Einstein Current Tank Info: 360 degree walk around 300 DD island–4 300W & 2 165W ViparSpectra, 4 Kessil A350W, 2 A360WE, 3 XF150, 1 XF250, 1 XF350 Gyre along with 2 PP40 and 2 IceCap 3K gyre for robust current. Basement 150 gallon RubberMaid sump, SKIMZ skimmer, DCP18000

11/08/2007, 01:54 PM	#2
renisel Registered Member Join Date: Mar 2007 Location: Phoenix, AZ Posts: 866	I think having glass over the top would tend to drastically increase the heat issues that come with MH. Not only does the glass absorb some light and turn it into heat, but it also greatly inhibits evaporation (evaporation lowers the temperature of the water). Personally, I would go with the eggcrate or mesh.

11/08/2007, 02:35 PM	#4
renisel Registered Member Join Date: Mar 2007 Location: Phoenix, AZ Posts: 866	OK, I guess that so long as the sump has a decent surface area, the evaporation won't be as big of an issue (but it will still have an effect). As for using Lexan, the info I found said its working temperature (the temperature range in which it won't be excessively malleable or brittle) goes up to 239 F. So, I'd put a thermometer below the light at the height where the lexan would sit, and see what the temperature is with your lights on. So long as it's well below 239, I'd think Lexan would work just fine.

11/08/2007, 03:38 PM	#6
JaredWaites Premium Member Join Date: Sep 2007 Location: Destin, FL Posts: 1,482	I don't think you'll have an issue with Lexan, pending how high the lights are away. Plexiglas is 15X stronger than glass, Lexan is 250X stronger than Plexiglas, and that's not a made up number...but personally since Lexan can be expensive, I'd go with glass if you can...I'd also make sure after you have it cut, that they temper it because I'd hate to see water splash on the glass and shatter your plate glass and make shards, they are a PITA to clean up. Good Luck.

11/09/2007, 06:53 AM	#9
hmello@bermexin Registered Member Join Date: Jan 2007 Location: Michigan Posts: 1,205	Good information everyone. Thank you for all of the options. I am going to contact a local glass shop today to see if they can cut and finish the sides of a pc. of tempered glass. If not I will probably try the Lexan route. This of course unless someone else comes up with a better alternative. Again thank you everyone. __________________ Henry Somewhere something incredible is waiting to be known. Current Tank Info: 29g BioCube, AI SOL 12" Super Blue