glass tops on my reef tank?

[hollister]

WOW . Your Salt Water Bio Sphere breaths life at the surface. You allow O2 to come in and unwanted gases to leave. Good water flow and open space is vital. Ive seen tanks with small fans to help air flow. Eggcrate is fine but open is best.

Its a no brainer , no lid........

[10reefman]

I used acrilic but it worpt now no lit.

[GSMguy]

Ok lets put aside the O2 depletion that glass tops cause for a moment.
My LFS has radions over their tanks and then put glass tops on them. It looks rediculous most of the light is refracted away from the tank and the tanks are dim.

I use a DIY window frame with 1/4" mesh, it works much better.

[driver3490]

I have done both partial and covered as well as no glass. Something is going to get salt on it period... It is easier and cheaper to clean glass than possibliy corode fittings and or abbbidently break a bulb. Just my opinion I have glass under the bulbs for safety now and a gap front and back.. I have a screen front and back on the "jumper" tank. In my case that one is freshwater.! just a thought

[nfored]

I use glass tops over my fowlr and I know that its not what your talking about but I have near 0 evaporation with the tank 98% covered for my eels protection. I am wanting to move to reef and I am also interested in this article I could use the neting But I must admit with all the tanks I have my house is much nicer with out 20 gallons a day of evaporations.

As far as glass goes and light I suspect that has a lot to do with the quality of the glass, kinda like buying a 1000.00 nikkor lens with multi coating compared to buying a cheap single or no coated lens.

[HurricaneSystem]

I use glass tops and I have tried without, notice no difference. Let me ask you something, let's say you have a 60's model car with plain glass, you have the windows rolled up in the summer. If you have your arm on the door (inside) will you get sunburned?

Yes you will, so with that simple analogy, I see no way it could affect corals unless you let it get completely covered in salt creep.

[nfored]

Well I think its more of the wave length, let me go back to photography I bought a POS UV filter to protect my lens, I took some pictures and notices some loss of color and poor handing on flares; I bought a better B+W UV filter, and saw none of the same issues.

So while not the same it is proof that the type of glass matters when it comes to what light wave lengths pass through and at what angle they pass through. But I personally think that glass top will likely not matter much if it does move the light closer.

[bkhunt]

I just took off my glass tops because my tank is to warm. I cut some gutter gaurd and have it leaning against my T5 light fixture. I am hopeing that this is a temp fix until I read all the post above for a better idea.

[kissman]

Get a $10 clip on fan from walmart and have it blow across sump if u have one! Will drop temp a few degrees. Goto www.bulkreefsupply.com and invest in diy screen tops

[rjcranor]

I use glass tops on my 50 clean glass when I do my monthly water change.

[wildman926]

Unless there is no sump, and the top is totally sealed with the glass touching the water, there is no O2 depletion using glass tops.

[James77]

Originally Posted by rjcranor

I use glass tops on my 50 clean glass when I do my monthly water change.

How bad is the salt creep on the glass monthly?

[HurricaneSystem]

Salt creep isn't too bad really, just need to rinse them off once a month and wipe it down with a paper towel. I have some space, around 2 inches, in the back for things like my return, etc. So the top isn't completely covered.

I have a couple of cats, so I also leave them on so that they don't go swimming at night. Don't ask me how I know this, lol.

[kissman]

i can see a difference if I slowly slide my glass tops on I can see a difference in the light on my corals. I also notice more shading. I went with no tops for years and when I got my Gobies I put on screen tops to keep them in. I like that I have much more oxygen flow across the surface with 1/4" screen and less light reflecting back onto my bulbs that could cause them to need replacing sooner.

[kissman]

[roberthu526]

I know this is an old thread but still want to contribute some of my opinions:
1. With modern technology in LED lighting the light loss is no longer an issue. Regarding wave length, many people have had success with glass top so it doesn't seem to be a big deal;
2. If you keep your entire tank top sealed and you don't have a sump, then O2 restriction is going to be a problem. But if you have 10-20% of the top open to air and have powerheads pointing to the surface of the water, you will be fine;
3. Glass top does block spills thus salt build-ups. It will help extend light life and reduce maintenance. It also keeps the salt withing the tank water and reduce the need of topping off so it helps keep stable salinity level;
4. Keeping jumpers inside. This is pretty obvious...

Just my 2 cents based on my own experience.

[Twoteal]

Glass drilled with fans for in and out.

[Imaexpat2]

Originally Posted by malawinovice

The glass tops get salt spray and get cloudy quick. The also inhibit the exchange of air/water at the top surface of the tank.

I would raise your t5 to 4 inches above the tank. That should cut down on the salt spray.

I built a 3/4 wood canopy to allow the fixture to sit above the tank and allow access from the front.

+1 to that! Making a canopy to raise your lights about 5.5 inches out of 1x6's is really easy and fairly cheap and will eliminate about 90% of the issues you have without heat build up and Air exchange with water and keep your light in the tank instead of spilling out in the room. 1x6's will give your lights about a 4 inch lift above the tank top significantly reducing the issues you have. By using glass tops your just moving the problem you have from your lights to the glass top and dropping the PAR of your lights over the tank.

I am using such a canopy that I built in about 20 minutes to hold my 4 x 24 inch T-5HO fixture above my 20 gallon tank. I got no issues with salt creep on the light and I didnt reduce the PAR over the tank either. It cost me one 8ft 1x6 and 1 8ft 1x1 and about 1/8th pound of finish nails and some gorilla glue and a can of Black Spray paint.

[discussmith]

Not to step on anyone’s toes who think too much light is lost through glass tops, the actual light loss due to reflection is closer to 4%. If you have “starfire” type glass or crystal it will be almost none. The light will slow down (or refract) as is passes through denser materials like glass and water.

[discussmith]

I neglected to say there can light absorption due to inclusions of contaminants in the glass.

[Oldreeferman]

Ive always used glass tops on my tanks and it made no diff in growth verses the growth id seen on similar corals in open top DTs.
Also, i use telescopes & coatings are important when looking at extremely dim objects and trying to squeeze every single photon you can for a time lapse CCD pic or when just viewing due to optics size & light grasp, that being said bright daytime lighting over a tank is pretty much a non issue coatings or not if the glass is kept clean as the Oceans reefs are at all different pars everywhere at different depths & locations.
Salt creep does blow & it will over time etch the glass as will the mag & Cal so i replace my glass once a yr, the price is under $20 and its a must do as the glass gets badly hazed eventually but the positives outweigh this with min evap & no fish jumping issues ever, i do have the back 2" open for air movement and access to allow dosing & feeding.
I run a fan on it during Summer & it holds temp at 78 spot on.
I realize this is a really old post but figured id put in my exp. on the matter if anyone is contemplating & wants to consider all sides of the issue.

[Imaexpat2]

Its not so much that light is blocked by glass as much as dust on it and salt creep on the glass acts as one heck of a light diffuser.

[Oldreeferman]

Yea, i agree its the salt creep that is the issue.
My glass tops started out as store bought 2pc types with a dark flexible plastic hinge but the hinge blocked the light so i removed them then... salt creep big time was an issue...So, the fix was a 1 pc larger glass cover in 1/8" safety glass, no more creep issues except a bit at outer edges.
I still left the 2" open at the back & put the lift handle back on front middle works 10 times better then a 2 pc. I can not imagine why the manufacturers do not make clear hinges unless light effects them or they think its a dirt & stain catch area?

[Imaexpat2]

@ Oldreeferman....the number of times I have asked myself that very same question is uncountable, and there aint too many things as special as a shadow through the middle of your display tank!

[Oldreeferman]

I hear ya, i think the manufacturers focus these glass lids twards fish only or freshwater customers where light is not anywhere nearly as critical as is for coral.