Lighting through a glass top?
 

I have noticed by looking at many pics that most people do not have their SW tanks covered...

Does this have anything to do with the light getting to the coral?

What about the fish how often are fish lost due to lack of cover?

I was thinking a simple 5mm single sheet (NOT the 2 overlapping/ slide type) glass top...

Any comments or thoughts would be great :)

Fish do jump, and many people have canopies or egg crate over their tank. Both those options allow for fairly open (sometimes fan-assisted) air flow. Putting glass over it will trap heat and limit oxygen exchange, and that's not so good. In addition, the salt splash and evap/condensation will (I'm guessing) make the glass opaque quite quickly, which will limit the effectiveness of your lights.

Hi Matt

When you say Egg Crate, are you talking about the plastick checkered type stuff (white plastic all squares) - where do you get that from?

Thank you!

i think it has a lot to do with more surface area expose to air.... supposed to be good for tank. "airgation" (sp?) something like that.

i ve lost 2 fishes due to jumpers, 1 was a mandarin and the other was a pearly jawfish and the jawfish is known to be a jumper. i just didnt listen....

I have a glass top on my cube tank & have to wipe the underside of the glass every day.

Having a Korallia pointing towards the surface probably doesn't help too much but it gets pretty opaque if I don't clean it for more a few days.

I'm getting a bit p***ed off with it at the moment & will change it for an egg crate pretty soon & live with the extra evaporation (the tank has an ATO).

.

Can someone post a picture of an egg crate and let me know where I can get it :)

here's some pics
 

http://homepage.ntlworld.com/k.davis...tank8.06/7.jpg
http://www.collins-consulting.org/orchids/eggCrate.jpg

You maybe get it at Rona? Home Hardware? Home Depot? Commercial lighting suppliers?

.

bump for the best eggcrate pic ever.
Very nice.
what kind of camera did you use?
:mrgreen:

I used the mighty Google Imaging Camera :lol:

(I'd never have 80's style grey carpet with coloured flecks!)

.

Eggcrate is good for so many things, I think most of us have a least a partial sheet in our garages :p

You can get eggcrate at any of the big box home improvement joints. You just need to ask for a light diffuser as most people working in the stores will look at you with crossed eyes if you call it eggcrate :p

I used to use it when I had a tank with a plastic rim on it.. if your tank is eurobraced it makes it a little trickier to secure to the top of the tank.

This is great - I will go look for some :)

thank you!

Would having a glass top, but open sump(in stand w/open back) Limit the O2 transfer and keep heat in? When I upgraded my lights, I had my tank open for a week. Evap was crazy, 1g/day and thats only T5, not MH. I also noticed that the tank temp rose a few deg. Now, with a 5mm glass top, and the TEK 4 tube 24" light tank runs 80.8 in the day, no heater. Evap is less, bout 0.6g/day. I dont want to lose fish due to jumping, nor do I want to be filling RO every day

I use eggcrate in my sump to elevate "things"..... but would it soften or melt somewhat under the heat of the MH lights?

Hmm, in doing some testing with a sheet of eggcrate and my Tek light. The eggcrate takes away a little ligth and reduces what little shimmer I have to nothing. The glass top reduces about the same light as viewed through the side of the tank, but the shimmer is still there. Just testing the difference in tank heat with/without the glass cover right now.

i just recently took my glass off, it was standard 3mm, happy so far, but omggg evaporation is ridiculous without a top, i used to top up every few days now it's every single day 1/4'' gone, then again i did it for good gas exchange so thats the way it's staying, thinking of eggcrate though-

Old school reefers actually would want MORE evaporation - why? It allowed more the addition of more kalk. The need for kalk has lessened with the advent of Ca reactors and two-part dosing, but you should still take full advantage of your tank's ability to shed water. Kalk helps maintain Ca/Alk and keeps your pH up, plus it's dirt cheap in bulk (relatively speaking). Just get an ATO if you don't want to top up manually.

Anyway, glass tops cut down on PAR significantly. Just check out Sanjay's spectral plots of shielded vs unshielded MH bulbs.

do they really cut down on PAR that much? i remember one of the staff members mentioning that it barely lowered PAR by a few percent, and that some 95'ish% of light gets through, good to know though

Here are Sanjay's results for 150W DE HQI bulbs both with and without a 1/8" glass shield:

http://www.reeflightinginfo.arvixe.c...&Submit=Submit

The glass causes a good 20% loss of PPFD (a.k.a. PAR) for nearly all bulbs.

thanks for the link, 19% up for me! unreal it was thin glass too, 3mm

and that's WITHOUT 1/8" salt creep built up on the glass to boot. you'll lose a lot of light so it's a major tradeoff you'd have to consider if running a glass top.

using egg crate on halides is a bit of a pain with most reflectors because it'll block a lotta light on the outer edges. egg crate's really only best for flourescent lighting. maybe look into an auto-top off unit? i love mine.

a good ol' canopy works wonders for keeping fish in :)