Reefs.org Forums

[MaineReefer]

Hey all. A few questions about glass tops. I just read that it is NOT a good idea to keep the glass tops on your tank. I know this is for gas exchange and cooling, but can someone elaborate on the gas exchange? If I keep them on will it screw up my new 75g set up? Also, how high above the tank, should I put my T5 HO light? (1) 10,000k, (1) 14,000k (1) 420 actinic (1) 460 actinic. It comes with legs of course, but would I benefit from it being lower?
Any info would help!

Thank you!!

[Len]

It won't screw up your tank horribly, but it does have a significant effect on your tank's chemistry such as lowering your pH. It will also increase your temp. And as time goes by, the glass will get dirty and absorb over 50% of the light ... a huge waste of electricity. It also makes servicing the tank a lot more annoying.

There's really no good reason to use glass unless you want to prevent fish from jumping, and there are better solutions to this than using the glass.

[Lawdawg]

The gas exchange is inhibited by the stale air (no movement) that you get when you pt glass tops on a tank, in effect as Len as said making the tank water more acidic. Lots of people make mesh tops if you keep fish that are prone to carpet surfing.
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As far as the light fixture, I'd use the legs that came with it. It's an airflow issue for one, using the legs allows airflow around the fixture. Besides, lowering the lights also increases the chance of an accidental splashing and electricity, hot lamps and saltwater do not play well together!

[MaineReefer]

Excellent. Thank you so much. Glass tops are going in the closet. I will get some of that mesh you're talking about. I know what it is, I've seen it before. I just wasn't sure exactly WHY it was being used. Again, thank you!! Will let ya know how it works out.

[cjdevito]

Dissenting opinion...

Glass tops are handy. They're pretty much the most fool-proof way of preventing jumpers, but also they can do a lot to prevent much evaporation. Lots of people will tout the benefits of evaporative cooling and they're absolutely right about that... but there are times and situations where being able to limit the amount of top off water needed is a good thing. If you don't have an auto-topoff device and you do much travelling, having a glass lid makes vacations less of a trauma on the tank. If you're worried about your water bill and all the waste water from using your RO unit, using lids means you'll use a lot less. And if your source water for top offs isn't the best quality to begin with (for whatever reason), needing to use less of it over time is a plus.

If you keep cats, lids can be a neccessity. If you have small children with a tendency to drop things into a tank, lids can be a neccessity. Lids also stop airborne pollutants from landing in the water... all the dust, pollen, pet hair, glitter from your 2nd grader's art project gets stopped.

Lowered pH is largely a myth. Can it happen when using a lid? Sure - assuming you aren't using a protein skimmer or even an air stone somewhere in the set up. Passive gas exchange at the surface is reduced when using a lid, but injecting air and the surface turbulance resulting from it pretty much negate that as an issue.

It will increase your tank temp compared to running topless, definitely. But if you're keeping any truly escape-prone fish, need to keep something out of the tank, or need to limit tank evaporation, lids have their uses.

[MaineReefer]

Thank you for your input. I know everybody has a way of doing things but hearing all sides of it definately helps. Again, thank you fo ryour input!!!