Should I not have glass lid on tank for better light?

StoutLager · #1 03/04/2006, 09:38 PM

I have Hetal Halide lighting and glass lid on aquarium.

Is this a problem for the efficiency of the lighting?
If so, how much light am I losing due to reflection and refraction?
Is this possibily why I do not have coraline algea growing?

I have it there to prevent fish from splashing water everywhere and all over lights.

szwab · #2 03/04/2006, 09:44 PM

you should not have a glass lid for lighting and because it greatly reduces gas exchange.

as far as protecting your lighting I've never had problems just keep the halides 6-12 inches off the surface. Depending on the thickness and type of glass I believe you could lose up to 20% more once you figure in salt creep and other dirt. Lack of coraline might also be a sign that either or both of your calcium and ALK levels are out of whack.

StoutLager · #3 03/04/2006, 10:12 PM

Can you please expand on this 'gas exchange' that is supposed to occur. Which gases are going which direction from what processes?

Andy O · #4 03/04/2006, 10:58 PM

What are you using for lighting. Be careful if you are using a SE retro bulb that is not protected by some type of glass. Those bulbs get awfully hot and if water splashed on them they can crack.

Besides cutting down on lighting and the salt creep build up on the glass, the glass top will also hold heat in so be prepared for the possability of a temp issue insdide the tank, espcially in the summer time.

I see that you have some jumpers in the tank so that is another factor that you have to weigh about having a glass top -- finding them carpet surfing.

szwab · #5 03/04/2006, 11:46 PM

if you are worried about the fish you can replace the glass with eggcrate.

gas exchange would be co2 out of th tank and o2 into the tank along with heat exchange which is accomplished by turbulence at the water's surface the glass lid limits this by creating a closed system that as mentioned will also hold heat.

HowardW · #6 03/05/2006, 01:21 AM

I remember just looking at a chart somewhere about how much affect both glass and acrylic have on blocking various lights, but i can't remember where now. I do remember that 1/8th" glass or acrylic wasn't awfully terrible on cutting down the light reaching the tank, but that is also assuming you keep the glass perfectly clean, and also as someone mentioned a covered tank with a hot lamp(s) will definately have a greenhouse effect and raise the water temp.