[lizandcourtney]

Hi All,

I'm new to the forum, however I've had a reef tank for about 2 years now. I just upgraded to a 29 gallon from a 20 g Long, and with the new tank I bought a glass top.

I was wondering, with my lighting, 69 watt 50/50 PC fixture, would a glass topper be beneficial or will it just block the rays?

I'm trying my luck with LPS again, and just bought a bubble coral, and open brain coral. They are both on the very bottom of the tank. I have other corals as well, mostly zoo, polyps and shrooms.

Thanks for your input,

Liz

[pyromaniac398]

Glad we could resolve this in chat Welcome to RB by the way. We need pics!

[pogodzib]

The only thing that a glass top does is minimize the gas exchange (bad), blocks rays (bad), prevent fish from jumping out (good), and protect the light bulbs from getting water splashed on them (good). My using egg crate instead of glass, you can prevent the fish from jumping out and by raising the lights high enough, you can prevent water from splashing on the bulbs without reducing the useful light in the tank.

[unclejed]

To respond to pog, blanket statements on any subject are usually bias toward what the speaker believes. If you use a hob filter or canister than maybe gas exchange is hindered "somewhat". If you have good surface agitation however, maybe not. If you employ a sump, then you get all the gas exchange you need not to mention if you have a skimmer. I have always used glass tops with no ill effects what so ever. As far as light rays being diminished, that to is a misnomer as far as the glass having any real overall "bad" effects. How high are the lights above the tank? What type of lighting? Is the glass non-reflective? All these have a bearing and from my research into this very subject, the diminished effect glass has on the light is minimal. Your water itself has a far greater effect on how much penetration you are getting, thus, proper intensity is now the idea instead of watts per gallon.

[ianizaguirre]

if u dont have fish that jump you could loose the egg crate

[lizandcourtney]

So, basically there are mixed feelings about the Glass tops? I don't have any fish that jump, but I'd still like to cut down on water evaporation. I was dumping 1/3 gallon of fresh RO water everyday without the top, and have noticed that this evaporation has been cut down drastically with the glass top on. Does egg crate help with evaporation?

I'm not worried about gas exchange because I have a HOB filter and a skimmer.

Also, the light fixture I use comes with a thin plastic cover that slides out to protect the bulbs from water splash. Do you think that plastic also impedes the light as well.

PS. I'll get some pics soon.

[ianizaguirre]

just loose the glass top and keep up with evaporation thats a tank and the glass on the loght itself dosent take away light

[pogodzib]

There has been studies and tests from reef keepers that have light meters that show that egg crate doesn't reduce the lighting intensity at all, clean glass tops reduce the intensity by approx 8%, glass tops after a couple weeks of use without cleaning varies between 10-15%, and dirty tops can reduce the intensity my up to 25%.

1/3 gallon per day is small for evaporation. Many reef tanks evaporate multiple gallons per day.

With that lighting, I'd loose the glass top because every little bit of lost light could affect your corals greatly.

Responding back to unclejed's comments, surface agitation and canister filters won't help substantially if the gas can't escape because of a closed top. If you have a sump that gets good air circulation through it, then it may provide enough gas exchange, but that is not always the case if the sump is placed inside of a stand. The only way you can help test to see how your tank is doing for gas exchange is by testing for certain levels that can help you judge if your tank isn't getting proper gas exchange. A couple of those test are testing for dissolved oxygen and pH. Tanks with low dissolved oxygen and pH levels may have poor gas exchange, but the low levels may also be being caused by something else such as dirty water, temp, alk levels, etc...

If you setup a poll between for how many people use glass tops over a reef tank compared to how many people use either nothing or egg crate, you'll find that less than 20% of reef keepers use glass tops. And if you add experience into the equation, you'll find that beginners are much more likely to use glass tops than more experience reef keepers. Some of that might be based upon the fact that there are more beginners using less powerful lighting that doesn't put out the heat that many more experienced reef keepers use and it is tougher to keep a tank cool with glass tops.

[demonsquirt]

Cant be any mixed feeling. In a SW tank placing any cover will hinder amount of dissolved oxygen in the water.Also your waters PH will suffer and this will also increase water temp.

Firstly, water movement will overcome the problem of thermal layering by mixing the warm and cold water layers, so we end up with an evenly heated tank.

The movement of water in the tank also prevents the formation of a film on the water surface, which would inhibit gaseous exchange between the water and the air.

Water moving around the tank effectively increases the surface area of the tank by constantly changing the layer of water in contact with the atmosphere. This, of course, dramatically increases the rate at which oxygen can be dissolved into the water and carbon dioxide released into the air. Well oxygenated water is essential for the health of the fishes, plus, we can keep more fishes in a given space if the water is well oxygenated.

Moving water carries oxygen to the nitrifying bacteria in the tank, which are responsible for the breakdown of harmful waste products, and also carries nutrients to the plants.

A strong movement of water in the aquarium, as produced by a power filter, provides the fishes with a current in which to swim, and many fishes find this both enjoyable and beneficial.

As you can see then, water movement in the aquarium can be tailored to suit the type of environment we wish to establish.