Polycarbonate tank cover

tc2007 · 01/03/2015, 10:35 AM

This isn't 100% DIY, as a friend actually made this for me. I was having a lot of water evaporated out of my 90G cube and also worried about fish jumping out. So I came up with this idea of a Polycarbonate (Lexan clone material) cover with a round hole in the middle to let my Kessil A350W shine through.

Finding a 30X30X1/4" sheet was hard. So I got a 24X36 and a 9X36 then cut it to size. the smaller piece is in front and acts as a lid. I have not hinged it yet.
I also have 2 small holes in front to drop food. I can already see lot of water sticking onto the surface so hoping it will cut the evaporation a lot.

sleepydoc · 01/03/2015, 11:08 AM

Some things to be aware of with a polycarbonate (or acrylic) cover like this -
- they can limit air circulation and oxygen exchange, which may be an issue, especialty for a more heavily-stocked tank
- you don't have a much evaporation which reduces evaporative cooling and/or leads to heat buildup. Depending on your lighting, equipment and ambient temperature this may be significant
- Polycarbonate tends to yellow somewhat with UV light (I don't think this is an issue with acrylic)
- It looks nice now, but after a few weeks/months there is generally significant salt-spray buildup. This also can signficantly reduce the light transmission. (probably not an issue for you since you have a single pendant light over the hole)
-if jumping is an issue, that hole still provides ample space for a critter to jump out. I had a gobie jump out a hole that was smaller than a quarter once! As someone once said - even if the hole is small, the fish have nothing else to do all day!

Because of these issues, most people generally us ¼" clear netting like this:
http://www.bulkreefsupply.com/clear-netting.html#

If none of these turn into an issue for you, great!

tc2007 · 01/03/2015, 11:12 AM

Yeah, I might put an egg crate over the round hole. At this time I don't have any such fish except my firefish but it never comes to the top. At second thought, I should have kept the feeding holes a bit smaller. If the fish still want to jump out be my guest

sfsuphysics · 01/03/2015, 11:17 AM

Remember what "egg crate" is actually used for, it's a light diffuser material for fluorescent lights so you don't see light from odd angles. If you put that over your hole under the light you're going to reduce the spread of your light source.

That said, if you do stay in this direction, you might want to put some bracing on it, even at 1/4" over a span of 30" as it heats up it will sag, and once it sags it'll be a lot harder to brace it.

tc2007 · 01/03/2015, 11:56 AM

OK thanks for the tip.

01/03/2015, 10:35 AM	#1
tc2007 Registered Member Join Date: May 2014 Location: Midwest Posts: 867	Polycarbonate tank cover This isn't 100% DIY, as a friend actually made this for me. I was having a lot of water evaporated out of my 90G cube and also worried about fish jumping out. So I came up with this idea of a Polycarbonate (Lexan clone material) cover with a round hole in the middle to let my Kessil A350W shine through. Finding a 30X30X1/4" sheet was hard. So I got a 24X36 and a 9X36 then cut it to size. the smaller piece is in front and acts as a lid. I have not hinged it yet. I also have 2 small holes in front to drop food. I can already see lot of water sticking onto the surface so hoping it will cut the evaporation a lot.

01/03/2015, 11:08 AM	#2
sleepydoc Registered Member Join Date: Oct 2011 Location: Minneapolis, MN Posts: 3,907	Some things to be aware of with a polycarbonate (or acrylic) cover like this - - they can limit air circulation and oxygen exchange, which may be an issue, especialty for a more heavily-stocked tank - you don't have a much evaporation which reduces evaporative cooling and/or leads to heat buildup. Depending on your lighting, equipment and ambient temperature this may be significant - Polycarbonate tends to yellow somewhat with UV light (I don't think this is an issue with acrylic) - It looks nice now, but after a few weeks/months there is generally significant salt-spray buildup. This also can signficantly reduce the light transmission. (probably not an issue for you since you have a single pendant light over the hole) -if jumping is an issue, that hole still provides ample space for a critter to jump out. I had a gobie jump out a hole that was smaller than a quarter once! As someone once said - even if the hole is small, the fish have nothing else to do all day! Because of these issues, most people generally us ¼" clear netting like this: http://www.bulkreefsupply.com/clear-netting.html# If none of these turn into an issue for you, great! __________________ ~~~~~~~~~~~~~~~~~~~~~ 120 gallon, coast to coast overflow w/beananimal overflow. Waveline DC 10000 II return pump, 40 gal sump, Octopus XS200 skimmer, T5 lighting

01/03/2015, 11:17 AM	#4
sfsuphysics Registered Member Join Date: Jan 2004 Location: San Francisco Posts: 9,103	Remember what "egg crate" is actually used for, it's a light diffuser material for fluorescent lights so you don't see light from odd angles. If you put that over your hole under the light you're going to reduce the spread of your light source. That said, if you do stay in this direction, you might want to put some bracing on it, even at 1/4" over a span of 30" as it heats up it will sag, and once it sags it'll be a lot harder to brace it. __________________ Mike

01/03/2015, 11:12 AM	#3
tc2007 Registered Member Join Date: May 2014 Location: Midwest Posts: 867	Yeah, I might put an egg crate over the round hole. At this time I don't have any such fish except my firefish but it never comes to the top. At second thought, I should have kept the feeding holes a bit smaller. If the fish still want to jump out be my guest

01/03/2015, 11:56 AM	#5
tc2007 Registered Member Join Date: May 2014 Location: Midwest Posts: 867	OK thanks for the tip.