Cover reduce light?

[serratus]

I was just thinking, does having a glass cover on top of the aquarium reduce the light that goes into it since the condensation on the cover would refract and reflect some of the light away from the tank?

Is this why people buy stands for their lights so that they don't need to have a glass cover to sit on?

BTW, I'm just starting out so I don't even know if tons of condensation even forms on the cover but I do recall see condensation on the glass cover of aquariums in stores.

Without the cover, will the tank get noticeably dirtier faster due to dust landing into it? (i.e. you gotta clean your filter more frequently)

[Delphinus]

Yes to basically all your questions.

Sometimes cover glass is necessary, ie., if you have fish that are known to be prone to jumping or attempting escape from their glass prison. However even then there are no guarantees. Some people prefer glass covers to keep evaporation in check.

But not only does a clean piece of glass reduce some light, anything that gets on it will too, not the least of which is salt creep. If you want to use glass you'll need to clean it on a regular basis.

I prefer open-top myself, but it's better to find your own comfort level.

FWIW, I wouldn't trust the glass to hold up a light, I think it's better that a light has some structural support other than the glass over the tank - if that glass gets bumped or something, you don't want that light to fall into the tank - it's better if it's suspended above the tank, or secured to a canopy or hood.

[fkshiu]

Glass covers can also prevent proper gas exchange causing excess co2 in the water thereby driving your pH down.

[Trigger Man]

To my suprise I was over at Kwirkys one day picking up a coral and he had just gotten a light meter. We ended up testing the difference between light to water, light with glass cover to water, and light with glass with lots of salt creep and some other guck to water. We thought that the light penetrating the glass that had lots of salt creep and some guck on it woud have a huge difference, but in the end the light readings came in very similar. I was suprised as I used to clean my glass lids covering my tank every day or so, but now I typically just lift my glass at an angle every day so the condesation drips back into the tank and then clean the glass every couple of weeks.

[fkshiu]

Originally Posted by Trigger Man

To my suprise I was over at Kwirkys one day picking up a coral and he had just gotten a light meter. We ended up testing the difference between light to water, light with glass cover to water, and light with glass with lots of salt creep and some other guck to water. We thought that the light penetrating the glass that had lots of salt creep and some guck on it woud have a huge difference, but in the end the light readings came in very similar. I was suprised as I used to clean my glass lids covering my tank every day or so, but now I typically just lift my glass at an angle every day so the condesation drips back into the tank and then clean the glass every couple of weeks.

Were you using a lux meter or a PAR meter for your readings? Sanjay Joshi's test show a PAR reduction of around 10-20% with a pane of tempered glass that is used for DE MH bulbs.

[Rbacchiega]

let's not forget retained heat! Especially if you're using MH bulbs. Also, if you're resting the lights on the glass, you risk overheating, wrecking either your lighting unit or the glass!

[fdiddy]

Originally Posted by fkshiu

Were you using a lux meter or a PAR meter for your readings? Sanjay Joshi's test show a PAR reduction of around 10-20% with a pane of tempered glass that is used for DE MH bulbs.

I don't think tempered would be the best way to go with this anyways. Glass only prevents certain frequencies of light from passing through due to the refractive index. I think most panes of glass will let sufficient light through, less than 10% reduction I believe. Just my humble opinion - No back up evidence other than a few University Physics Courses.. which don't exactly cover PAR values and things of the sort.

[serratus]

"fish that are known to be prone to jumping or attempting escape from their glass prison"

Of the commonly kept reef safe fish, which ones are known to be prone to jump out of the tank?

Also, without a cover and with the light fixture raised on legs (TEK fixture), would you recommend using a splash shield to prevent salt buildup on the bulbs and water from splashing onto them? or would you say it is generally okay to go without the splash guard? Without the splash guard, TEK light fixtures don't have any kind of protection for the bulbs right?

[Delphinus]

Realistically, any fish has the potential to jump. But some are just worse for it than others. Fairy wrasses (any species), dartfish, jawfish .. eels.. I can't think of any others offhand but I'm sure the list is longer.

I have a Tek New Wave (cheaper unit, no splash guard, looks a little like a typical shop light except is T5HO), just hang it so that the lamps are about 3" off the water surface. Seems to be OK. I do have to wipe off the salt creep every couple of months but it's not significant. Otherwise it seems to be OK.

It doesn't really get splashed on per se, if it was, I'm sure this would be bad. But generally speaking you don't get splashing in a tank, only ripples. Where the salt creep comes from is air bubbles, when they pop at the surface sometimes a little tiny dot of water gets on the reflector or lamp, which of course puts a miniscule amount of salt when it evaporates. On a day to day basis it's negligible but over a couple of months I notice it and then just take it and clean it off.

[xtreme]

I know of a pink spot goby as well as long nose hawk that decided to take a hop.