Open or Closed Lid Tank, what are the downfalls?

[johnnycole]

Hello All...here's my first of many questions on this great forum!

I have a 105 gallon Amazon tank with 6 Firemouths and a pair of Blue Acara's. I bought the tank used and the guy was using a sheet of plexiglass as the cover. Well, plenty of water ends up forming under the plexiglass and the top of my light hood gets pretty wet, so I removed the plexiglass top.

My question is are there advantages/disadvantages in having an "open" tank?

[Lupin]

Advantages:
1. Temperature does not increase especially when you use lights.
2. CO2 is diffused more easily.
3. No condensation for floating plants. Pistia stratiotes in particular hates condensation forming on its leaves.

Disadvantages:
1. Fish and other creatures can escape the tank simply by jumping or clibing across ornaments on the part of the crustaceans and mollusks.
2. Dust and other unwanted objects fall to the surface.
3. If you have cats, they may attempt to wreak havoc on the fish.
4. Children can put anything harmful to the fish in the water.

[DeRo316]

Your will end up having to add water more often due to more evaporation as well

[jagarundi]

In the summer, if you have the tank in an un-air conditioned room, leaving the top up/off will help to dissipate the heat build-up in the tank. If you have jumpers, then that's not an option. Having a top on slows the evaporation process down and holds the heat in longer during cold months.

[johnnycole]

More evaporation means more fresh water!

[Plecosterone]

More evaporation means more fresh water!
You still need to do weekly water changes. Adding water to make up for evaporation is not the same thing.

[Joergen.Schoppe]

Open means lots of water lost, i lose 15 liter every week, 450l open tank
cannot put a lid, use metal halide, will be too hot otherwise...

[johnnycole]

Yeah, that evaporation thing was a joke Plecosterone ; )